Pre-AP Biology

TEACHER RESOURCES

Units 1 and 2

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 ABOUT COLLEGE BOARD
College Board is a mission-driven not-for-profit organization that connects students to college
success and opportunity. Founded in 1900, College Board was created to expand access
to higher education. Today, the membership association is made up of over 6,000 of the
world’s leading educational institutions and is dedicated to promoting excellence and equity
in education. Each year, College Board helps more than seven million students prepare for
a successful transition to college through programs and services in college readiness and
college success—including the SAT® and the Advanced Placement Program®. The organization
also serves the education community through research and advocacy on behalf of students,
educators, and schools.
For further information, visit www.collegeboard.org.

PRE-AP EQUITY AND ACCESS POLICY

College Board believes that all students deserve engaging, relevant, and challenging grade-
level coursework. Access to this type of coursework increases opportunities for all students,
including groups that have been traditionally underrepresented in AP and college classrooms.
Therefore, the Pre-AP program is dedicated to collaborating with educators across the country
to ensure all students have the supports to succeed in appropriately challenging classroom
experiences that allow students to learn and grow. It is only through a sustained commitment to
equitable preparation, access, and support that true excellence can be achieved for all students,
and the Pre-AP course designation requires this commitment.

ISBN: 978-1-4573-1519-0
© 2021 College Board. PSAT/NMSQT is a registered trademark of the College Board and National Merit
Scholarship Corporation.

The sentence-writing strategies used in Pre-AP lessons are based upon The Writing Revolution, Inc., a
national nonprofit organization that trains educators to implement The Hochman Method, an evidence-
based approach to teaching writing. The strategies included in Pre-AP materials are meant to support
students’ writing, critical thinking, and content understanding, but they do not represent The Writing
Revolution’s full, comprehensive approach to teaching writing. More information can be found at
www.thewritingrevolution.org.
Image credit page 73: Travelscape Images/Alamy Stock Photo; image credit page 179: Classic Image/Alamy
Stock Photo

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 Contents v Acknowledgments

INTRODUCTION TO PRE-AP BIOLOGY

3 About Pre-AP
5 Introduction to Pre-AP
7 Pre-AP Approach to Teaching and Learning
11 Pre-AP Professional Learning

13 About the Course

15 Introduction to Pre-AP Biology
22 Pre-AP Biology Course Framework
54 Pre-AP Biology Model Lessons
56 Pre-AP Biology Assessments for Learning
67 Pre-AP Biology Course Designation
69 Accessing the Digital Materials

UNIT 1
Ecological Systems

73 Overview
79 Lesson 1.1: Launch Lesson – Important Elements in Organisms
82 Lesson 1.2: Modeling the Water and Carbon Cycles
89 Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops
94 Lesson 1.4: Exploring and Modeling the Nitrogen Cycle
99 Practice Performance Task: Termites, Guardians of the Soil
104 Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web
110 Lesson 1.6: Population Field Studies Simulations Lab – Quadrat
and Mark–Recapture Sampling
124 Lesson 1.7: Launch Lesson – Comparing Biomes Using HHMI’s
BiomeViewer
128 Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects
132 Lesson 1.9: Modeling the Importance of Keystone Species
138 Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree
Snakes in Guam
145 Lesson 1.11: Predicting Changes in Arctic Ecological
Communities
154 Lesson 1.12: Understanding Beavers as Ecosystem Engineers

161 Performance Task: Exploring Species Interactions in the Great

Barrier Reef

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 UNIT 2
Evolution

179 Overview
183 Lesson 2.1: Launch Lesson – Examining Evidence of Evolution
190 Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus
199 Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs
205 Lesson 2.4: Modeling Natural Selection Lab
218 Practice Performance Task: Tusklessness in African Elephants
224 Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—
Salamander Evolution

233 Performance Task: The Flashy Guppy Data Analysis

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 Acknowledgments
College Board would like to acknowledge the following committee members, consultants, and
reviewers for their assistance with and commitment to the development of this course. All
individuals and their affiliations were current at the time of contribution.
Jason Crean, Lyons Township High School, Lagrange, IL
Rick Duschl, Penn State University, University Park, PA
Mark Eberhard, St. Clair High School, St. Clair, MI
Amy Fassler, Marshfield High School, Marshfield, WI
David Hong, Diamond Bar High School, Diamond Bar, CA
Kenneth Huff, Mill Middle School, Williamsville, IL
Michelle Koehler, Riverside Brookfield High School, Riverside, IL
Courtney Mayer, Northside Independent School District, San Antonio, TX
Elisa McCracken, Brandeis High School, San Antonio, TX
Jennifer Pfannerstill, North Shore Country Day School, Winnetka, IL
Nancy Ramos, Northside Health Careers High School, San Antonio, TX
Jim Smanik, Sycamore High, Cincinnati, OH
Keri Shingleton, Holland Hall, Tulsa, OK

COLLEGE BOARD STAFF

Karen Lionberger, Senior Director, Pre-AP STEM Curriculum, Instruction, and Assessment
Beth Hart, Senior Director, Pre-AP Assessment
Mitch Price, Director, Pre-AP STEM Assessment
Natasha Vasavada, Executive Director, Pre-AP Curriculum, Instruction, and Assessment

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 Introduction
to Pre-AP
Biology

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 About Pre-AP

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 About Pre-AP

Introduction to Pre-AP
Every student deserves classroom opportunities to learn, grow, and succeed. College
Board developed Pre-AP® to deliver on this simple premise. Pre-AP courses are
designed to support all students across varying levels of readiness. They are not honors
or advanced courses.

Participation in Pre-AP courses allows students to slow down and focus on the most
essential and relevant concepts and skills. Students have frequent opportunities
to engage deeply with texts, sources, and data as well as compelling higher-order
questions and problems. Across Pre-AP courses, students experience shared
instructional practices and routines that help them develop and strengthen the
important critical thinking skills they will need to employ in high school, college, and
life. Students and teachers can see progress and opportunities for growth through
varied classroom assessments that provide clear and meaningful feedback at key
checkpoints throughout each course.

DEVELOPING THE PRE-AP COURSES

Pre-AP courses are carefully developed in partnership with experienced educators,
including middle school, high school, and college faculty. Pre-AP educator committees
work closely with College Board to ensure that the course resources define, illustrate,
and measure grade-level-appropriate learning in a clear, accessible, and engaging way.
College Board also gathers feedback from a variety of stakeholders, including Pre-AP
partner schools from across the nation who have participated in multiyear pilots of
select courses. Data and feedback from partner schools, educator committees, and
advisory panels are carefully considered to ensure that Pre-AP courses provide all
students with grade-level-appropriate learning experiences that place them on a path to
college and career readiness.

PRE-AP EDUCATOR NETWORK

Similar to the way in which teachers of Advanced Placement® (AP®) courses can
become more deeply involved in the program by becoming AP Readers or workshop
consultants, Pre-AP teachers also have opportunities to become active in their
educator network. Each year, College Board expands and strengthens the Pre-AP
National Faculty—the team of educators who facilitate Pre-AP Readiness Workshops
and Pre-AP Summer Institutes. Pre-AP teachers can also become curriculum and
assessment contributors by working with College Board to design, review, or pilot the
course resources.

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 About Pre-AP

Introduction to Pre-AP

HOW TO GET INVOLVED

Schools and districts interested in learning more about participating in Pre-AP should
visit preap.org/join or contact us at preap@collegeboard.org.

Teachers interested in becoming members of Pre-AP National Faculty or participating

in content development should visit preap.org/national-faculty or contact us at
preap@collegeboard.org.

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 About Pre-AP

Pre-AP Approach to Teaching and Learning

Pre-AP courses invite all students to learn, grow, and succeed through focused content,
horizontally and vertically aligned instruction, and targeted assessments for learning.
The Pre-AP approach to teaching and learning, as described below, is not overly
complex, yet the combined strength results in powerful and lasting benefits for both
teachers and students. This is our theory of action.

Horizontally and
Vertically Aligned
Instruction
Shared Principles,
Areas of Focus

Focused Content
Course Frameworks,
Model Lessons

Targeted Assessments
and Feedback
Learning Checkpoints,
Performance Tasks,
Final Exam

FOCUSED CONTENT
Pre-AP courses focus deeply on a limited number of concepts and skills with the
broadest relevance for high school coursework and college and career success. The
course framework serves as the foundation of the course and defines these prioritized
concepts and skills. Pre-AP model lessons and assessments are based directly on this
focused framework. The course design provides students and teachers with intentional
permission to slow down and focus.

HORIZONTALLY AND VERTICALLY ALIGNED INSTRUCTION

Shared principles cut across all Pre-AP courses and disciplines. Each course is also
aligned to discipline-specific areas of focus that prioritize the critical reasoning skills
and practices central to that discipline.

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 About Pre-AP

Pre-AP Approach to Teaching and Learning

SHARED PRINCIPLES
All Pre-AP courses share the following set of research-supported instructional
principles. Classrooms that regularly focus on these cross-disciplinary principles allow
students to effectively extend their content knowledge while strengthening their critical
thinking skills. When students are enrolled in multiple Pre-AP courses, the horizontal
alignment of the shared principles provides students and teachers across disciplines
with a shared language for their learning and investigation and multiple opportunities
to practice and grow. The critical reasoning and problem-solving tools students
develop through these shared principles are highly valued in college coursework and in
the workplace.

Close Observation Higher-Order

and Analysis Questioning

SHARED
Evidence-Based PRINCIPLES Academic
Writing Conversation

Close Observation and Analysis

Students are provided time to carefully observe one data set, text, image, performance
piece, or problem before being asked to explain, analyze, or evaluate. This creates a safe
entry point to simply express what they notice and what they wonder. It also encourages
students to slow down and capture relevant details with intentionality to support more
meaningful analysis, rather than rushing to completion at the expense of understanding.

Higher-Order Questioning

Students engage with questions designed to encourage thinking that is elevated

beyond simple memorization and recall. Higher-order questions require students to
make predictions, synthesize, evaluate, and compare. As students grapple with these
questions, they learn that being inquisitive promotes extended thinking and leads to
deeper understanding.

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 About Pre-AP

Pre-AP Approach to Teaching and Learning

Evidence-Based Writing

With strategic support, students frequently engage in writing coherent arguments

from relevant and valid sources of evidence. Pre-AP courses embrace a purposeful
and scaffolded approach to writing that begins with a focus on precise and effective
sentences before progressing to longer forms of writing.

Academic Conversation

Through peer-to-peer dialogue, students’ ideas are explored, challenged, and refined.
As students engage in academic conversation, they come to see the value in being
open to new ideas and modifying their own ideas based on new information. Students
grow as they frequently practice this type of respectful dialogue and critique and learn
to recognize that all voices, including their own, deserve to be heard.

AREAS OF FOCUS
The areas of focus are discipline-specific reasoning skills that students develop
and leverage as they engage with content. Whereas the shared principles promote
horizontal alignment across disciplines, the areas of focus provide vertical alignment
within a discipline, giving students the opportunity to strengthen and deepen their
work with these skills in subsequent courses in the same discipline.
English

Mathematics

Social Studies
Arts

Science

Areas of Focus
Align Vertically Within Disciplines
(Grades 6-12) Academic Conversation

Higher-Order Questioning

Evidence-Based Writing
Close Observation and Analysis

Shared Principles
Align Horizontally Across All Courses

For information about the Pre-AP science areas of focus, see page 15.

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 About Pre-AP

Pre-AP Approach to Teaching and Learning

TARGETED ASSESSMENTS FOR LEARNING

Pre-AP courses include strategically designed classroom assessments that serve as
tools for understanding progress and identifying areas that need more support. The
assessments provide frequent and meaningful feedback for both teachers and students
across each unit of the course and for the course as a whole. For more information
about assessments in Pre-AP Biology, see page 56.

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 About Pre-AP

Pre-AP Professional Learning

Pre-AP teachers are required to engage in two professional learning opportunities.
The first requirement is designed to help prepare them to teach their specific course.
There are two options to meet the first requirement: the Pre-AP Summer Institute
(Pre-APSI) and the Online Foundational Module Series. Both options provide
continuing education units to educators who complete the training.

ƒ The Pre-AP Summer Institute is a four-day collaborative experience that empowers

participants to prepare and plan for their Pre-AP course. While attending, teachers
engage with Pre-AP course frameworks, shared principles, areas of focus, and
sample model lessons. Participants are given supportive planning time where they
work with peers to begin to build their Pre-AP course plan.
ƒ The Online Foundational Module Series is available to all teachers of Pre-AP
courses. This 12- to 20-hour course supports teachers in preparing for their Pre-AP
course. Teachers explore course materials and experience model lessons from the
student’s point of view. They also begin to plan and build their own course so they
are ready on day one of instruction.
The second professional learning requirement is to complete at least one of the Online
Performance Task Scoring Modules, which offer guidance and practice applying
Pre-AP scoring guidelines to student work.

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 About the Course

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 About the Course

Introduction to Pre-AP Biology

The Pre-AP Biology course emphasizes the integration of content with science
practices—powerful reasoning tools that support students in analyzing the natural
world around them. Having this ability is one of the hallmarks of scientific literacy and
is critical for numerous college and career endeavors in science and the social sciences.

Rather than seeking to cover all topics traditionally included in a standard biology
textbook, this course focuses on the foundational biology knowledge and skills that
matter most for college and career readiness. The Pre-AP Biology Course Framework
highlights how to guide students to connect core ideas within and across the units
of the course, promoting the development of a coherent understanding of biological
systems.

The components of this course have been crafted to prepare not only the next
generation of biologists but also a broader base of biology-informed citizens who are
well equipped to respond to the array of science-related issues that impact our lives at
the personal, local, and global levels.

PRE-AP SCIENCE AREAS OF FOCUS

The Pre-AP science areas of focus, shown below, are science practices that students
develop and leverage as they engage with content. They were identified through
educator feedback and research about where students and teachers need the most
curriculum support. These areas of focus are vertically aligned to the science practices
embedded in other science courses in high school, including AP, and in college, giving
students multiple opportunities to strengthen and deepen their work with these skills
throughout their educational career. They also support and align to the NGSS and AP
science practices of theory building and refinement.

Strategic Use
of
Mathematics
Emphasis
on Analytical Attention
Reading and to
Writing Science Modeling
Areas of Focus

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 About the Course

Introduction to Pre-AP Biology

Emphasis on Analytical Reading and Writing

Students engage in analytical reading and writing to gain, retain, and apply
scientific knowledge and to carry out scientific argumentation.
In prioritizing analytical reading, Pre-AP Biology classrooms ask students to extract,
synthesize, and compare complex information, often by moving between texts and
multiple representations, such as tables and graphs. Through analytical writing activities,
Pre-AP Biology students must integrate and translate that information to generate
scientific questions, design methods for answering questions, and develop scientific
arguments. Moreover, the application of these skills to the understanding of informal
science texts, such as articles found in newspapers, online sources, and magazines,
prepares students to be discerning consumers of scientific information.

Strategic Use of Mathematics

Students use mathematics strategically in order to understand and express the

quantitative aspects of biology, to record and interpret experimental data, and to
solve problems as they arise.
The ability to analyze and interpret data collected while investigating the natural world
is a critical practice for scientists. Once collected, data must be translated into forms
that can be analyzed in an attempt to reveal meaningful patterns and relationships.
These patterns and relationships are not always immediately obvious, so students must
become strategic in how they choose to apply mathematical and statistical thinking in
order to analyze data.

Attention to Modeling

Students go beyond labeling diagrams to creating, revising, and using models to

explain key patterns, interactions, and relationships in biological systems.
Modeling is a core practice for scientists as they use a variety of models to develop,
refine, and communicate their ideas about the natural world. Engaging students in
modeling also reinforces other scientific reasoning skills, such as data analysis and
scientific argumentation. Modeling also helps illustrate for students how scientific
knowledge is constructed and modified over time as new data and evidence emerge
and models are revised based on this new information.

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 About the Course

Introduction to Pre-AP Biology

PRE-AP BIOLOGY AND CAREER READINESS

The Pre-AP Biology course resources are designed to expose students to a wide range
of career opportunities that depend on biology knowledge and skills. Examples include
not only careers within the life sciences, such as marine ecologist or wildlife geneticist,
but also other endeavors where biology knowledge is relevant, such as the work of a
park ranger or healthcare policymaker.

Career clusters that involve biology, along with examples of careers in biology or
related to biology, are provided below. Teachers should consider discussing these with
students throughout the year to promote motivation and engagement.

Career Clusters Involving Biology

agriculture, food, and natural resources

healthcare and health science
human services
manufacturing
STEM (science, technology, engineering, and math)

Examples of Biology Careers Examples of Biology Related Careers

biology teacher/professor anthropologist

botanist biochemist
ecologist dental assistant/dentist
genetic counselor environmental scientist
marine biologist forensic scientist
microbiologist medical assistant
neurologist nurse
primary care physician pharmacist
veterinarian physician assistant
zoologist science writer

Source for Career Clusters: “Advanced Placement and Career and Technical Education: Working Together.”
Advance CTE and the College Board. October 2018. https://careertech.org/resource/ap-cte-working-
together.

For more information about careers that involve biology, teachers and students can
visit and explore the College Board’s Big Future resources:
https://bigfuture.collegeboard.org/majors/biological-biomedical-sciences-biology-
general.

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 About the Course

Introduction to Pre-AP Biology

SUMMARY OF RESOURCES AND SUPPORTS

Teachers are strongly encouraged to take advantage of the full set of resources and
supports for Pre-AP Biology, which is summarized below. Some of these resources
must be used for a course to receive the Pre-AP Course Designation. To learn more
about the requirements for course designation, see details below and on page 67.
COURSE FRAMEWORK
The framework defines what students should know and be able to do by the end of the
course. It serves as an anchor for model lessons and assessments, and it is the primary
document teachers can use to align instruction to course content. Use of the course
framework is required. For more details see page 22.
MODEL LESSONS
Teacher resources, available in print and online, include a robust set of model lessons
that demonstrate how to translate the course framework, shared principles, and areas of
focus into daily instruction. Use of the model lessons is encouraged but not required.
For more details see page 54.
LEARNING CHECKPOINTS
Accessed through Pre-AP Classroom (the Pre-AP digital platform), these short
formative assessments provide insight into student progress. They are automatically
scored and include multiple-choice and technology-enhanced items with rationales
that explain correct and incorrect answers. Use of one learning checkpoint per unit is
required. For more details see page 56.
PERFORMANCE TASKS
Available in the printed teacher resources as well as on Pre-AP Classroom,
performance tasks allow students to demonstrate their learning through extended
problem-solving, writing, analysis, and/or reasoning tasks. Scoring guidelines are
provided to inform teacher scoring, with additional practice and feedback suggestions
available in online modules on Pre-AP Classroom. Use of each unit’s performance
task is required. For more details see page 58.
PRACTICE PERFORMANCE TASKS
Available in the student resources, with supporting materials in the teacher resources,
these tasks provide an opportunity for students to practice applying skills and
knowledge as they would in a performance task, but in a more scaffolded environment.
Use of the practice performance tasks is encouraged but not required. For more
details see page 59.

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 About the Course

Introduction to Pre-AP Biology

FINAL EXAM
Accessed through Pre-AP Classroom, the final exam serves as a classroom-based,
summative assessment designed to measure students’ success in learning and applying
the knowledge and skills articulated in the course framework. Administration of the
final exam is encouraged but not required. For more details see page 60.
PROFESSIONAL LEARNING
Both the four-day Pre-AP Summer Institute (Pre-APSI) and the Online Foundational
Module Series support teachers in preparing and planning to teach their Pre-AP
course. All Pre-AP teachers are required to either attend the Pre-AP Summer
Institute or complete the module series. In addition, teachers are required to
complete at least one Online Performance Task Scoring module. For more details see
page 11.

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 UNIT 1
Ecological
Systems

Course Map ~25 Class Periods

Pre-AP model lessons provided for
approximately 70% of instructional
time in this unit
PLAN
The course map shows how components are positioned throughout
KEY CONCEPT ECO 1
the course. As the map indicates, the course is designed to be taught
over 140 class periods (based on 45-minute class periods), for a total Cycling of Matter in the Biosphere
of 28 weeks.

Model lessons are included for approximately 50% of the total KEY CONCEPT ECO 2
instructional time, with the percentage varying by unit. Each unit is
divided into key concepts. Population Dynamics

TEACH Learning Checkpoint 1

The model lessons demonstrate how the Pre-AP shared principles
and science areas of focus come to life in the classroom. KEY CONCEPT ECO 3
Shared Principles
Defining Ecological Communities
Close observation and analysis
Higher-order questioning
Evidence-based writing KEY CONCEPT ECO 4
Academic conversation
Ecological Community Dynamics
Science Areas of Focus
Emphasis on analytical reading and writing
KEY CONCEPT ECO 5
Strategic use of mathematics
Attention to modeling Changes in Ecological Communities

ASSESS AND REFLECT

Each unit includes two learning checkpoints and a performance task. Learning Checkpoint 2
These formative assessments are designed to provide meaningful
feedback for both teachers and students. Opportunities for formative Performance Task for Unit 1
assessment are also provided throughout the model lessons.

Note: The final exam, offered during a six-week window in the spring,
is not represented in the map.

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 UNIT 2 Evolution UNIT 3 Cellular Systems UNIT 4 Genetics

~20 Class Periods ~50 Class Periods ~45 Class Periods

Pre-AP model lessons provided for Pre-AP model lessons provided for Pre-AP model lessons provided for
approximately 40% of instructional approximately 40% of instructional approximately 35% of instructional
time in this unit time in this unit time in this unit

KEY CONCEPT EVO 1 KEY CONCEPT CELLS 1 KEY CONCEPT GEN 1

Patterns of Evolution Chemistry of Life Structure of DNA

KEY CONCEPT EVO 2 KEY CONCEPT CELLS 2 KEY CONCEPT GEN 2

Mechanisms of Evolution Cell Structure and Function DNA Synthesis

Learning Checkpoint 1 KEY CONCEPT CELLS 3 KEY CONCEPT GEN 3

Cell Transport and Homeostasis Protein Synthesis

KEY CONCEPT EVO 3

Speciation KEY CONCEPT CELLS 4 Learning Checkpoint 1

Organisms Maintaining Homeostasis

Learning Checkpoint 2 KEY CONCEPT GEN 4

Asexual and Sexual Passing of Traits

Learning Checkpoint 1
Performance Task for Unit 2

KEY CONCEPT CELLS 5 KEY CONCEPT GEN 5

Cell Growth and Division Inheritance Patterns

KEY CONCEPT CELLS 6 KEY CONCEPT GEN 6

Photosynthesis Biotechnology

KEY CONCEPT CELLS 7 Learning Checkpoint 2

Cellular Respiration and
Fermentation
Performance Task for Unit 4

Learning Checkpoint 2

Performance Task for Unit 3

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 About the Course

Pre-AP Biology Course Framework

INTRODUCTION
Based on the Understanding by Design® (Wiggins and McTighe) model, the Pre-AP
Biology Course Framework is back mapped from AP expectations and aligned to
essential grade-level expectations. The course framework serves as a teacher’s blueprint
for the Pre-AP Biology instructional resources and assessments.

The course framework was designed to meet the following criteria:

ƒ Focused: The framework provides a deep focus on a limited number of concepts

and skills that have the broadest relevance for later high school, college, and career
success.
ƒ Measurable: The framework’s learning objectives are observable and measurable
statements about the knowledge and skills students should develop in the course.
ƒ Manageable: The framework is manageable for a full year of instruction, fosters
the ability to explore concepts in depth, and enables room for additional local or
state standards to be addressed where appropriate.
ƒ Accessible: The framework’s learning objectives are designed to provide all
students, across varying levels of readiness, with opportunities to learn, grow, and
succeed.

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 About the Course

Pre-AP Biology Course Framework

COURSE FRAMEWORK COMPONENTS

The Pre-AP Biology Course Framework includes the following components:
Big Ideas
The big ideas are recurring themes that allow students to create meaningful
connections between course concepts. Revisiting the big ideas throughout the
course and applying them in a variety of contexts allows students to develop deeper
conceptual understandings.
Enduring Understandings
Each unit focuses on a small set of enduring understandings. These are the long-term
takeaways related to the big ideas that leave a lasting impression on students. Students
build and earn these understandings over time by exploring and applying course
content throughout the year.
Key Concepts
To support teacher planning and instruction, each unit is organized by key concepts.
Each key concept includes relevant learning objectives and essential knowledge
statements and may also include content boundary and cross connection statements.
These are illustrated and defined below.

Essential Knowledge
Statements:
About the Course

Pre-AP Biology Course Framework

The essential knowledge
KEY CONCEPT EVO 1: PATTERNS OF EVOLUTION statements are linked to one
Learning Objectives: Learning Objectives
Students will be able to …
Essential Knowledge
Students need to know that … or more learning objectives.
These objectives define
Theory of Evolution

EVO 1.1(a) Use scientific evidence to justify a claim of

an evolutionary relationship between species.
EVO 1.1.1 The theory of evolution states that the unity and
diversity of life we see today is the result of more than 3.5
These statements describe the
what a student needs EVO 1.1(b) Describe shared characteristics
(homologies) among organisms that provide evidence
billion years of evolutionary processes on Earth.
EVO 1.1.2 Scientists use various sources of evidence to
knowledge required to perform
for common ancestry. establish evolutionary relationships between organisms.

to be able to do with a. Fossil evidence, in conjunction with relative and radiometric

dating, provides insight into the geographic and temporal
the learning objective(s).
distribution of species throughout Earth’s history.

essential knowledge b. Comparisons of anatomical and molecular homologies are

used to determine the degree of divergence from a common
ancestor.

in order to progress 1. The structure and function of DNA is a homology that

links all living organisms across the three domains of
life—Archaea, Bacteria, and Eukarya.

toward the enduring 2. Cellular structures across all living organisms are
strikingly similar.

Classifying Evolutionary Relationships Content Boundary and Cross

understandings. The EVO 1.2(a) Create or use models to illustrate EVO 1.2.1 Evolutionary relationships between organisms can
evolutionary relationships. be modeled using cladograms and phylogenetic trees, which
show inferred evolutionary relationships among living things.
Connection Statements:
learning objectives
EVO 1.2(b) Use models of evolutionary relationships
to describe and/or analyze how different species are a. Cladograms and phylogenetic trees can illustrate speciation
related. events.
When needed, content boundary
serve as actionable
b. These models of evolutionary relationships show tree-like
lineages that do not correlate to levels of complexity or
advancement.
statements provide additional clarity
targets for instruction Content Boundary: The intent is not for students to memorize a list of characteristics that show descent from a common

about the content and skills that lie within

ancestor. Instead, the focus here is on a few powerful examples of this evidence—such as DNA and cellular structures—
that will help make discussions in Unit 3: Cellular Systems and Unit 4: Genetics more meaningful for students.

and assessments. Cross Connection: Revisit these topics to connect key concepts of shared characteristics across all living organisms

versus outside of the scope of this course.

as students explore the structure and function of DNA and cellular components in Unit 3: Cellular Systems and Unit 4:
Genetics.

Cross connection statements highlight

important connections that should be
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made between key concepts within
and across the units.
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Pre-AP Biology Course Framework

BIG IDEAS IN PRE-AP BIOLOGY

While the Pre-AP Biology framework is organized into four core units of study, the
content is grounded in four big ideas, which are cross-cutting concepts that build
conceptual understanding and spiral throughout the course. These ideas cut across
all four units of the course and serve as the underlying foundation for the enduring
understandings, key concepts, learning objectives, and essential knowledge statements
that make up the focus of each unit.

The four big ideas that are central to deep and productive understanding in Pre-AP
Biology are:

ƒ The process of evolution drives the diversity and unity of life.

ƒ Growth and reproduction in biological systems are dependent upon the cycling of
matter and the transformation of energy.
ƒ Biological systems, occurring at various scales, respond and adapt to stimuli in
order to maintain dynamic homeostasis.
ƒ Genetic mechanisms are essential to maintaining biological systems.

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Pre-AP Biology Course Framework

OVERVIEW OF PRE-AP BIOLOGY UNITS AND ENDURING

UNDERSTANDINGS

Unit 1: Ecological Systems (ECO) Unit 2: Evolution (EVO)

ƒ Biological systems depend on the ƒ The theory of evolution states

cycling of matter within and between that all organisms descend from a
Earth’s systems. common ancestor and share some
ƒ Most ecosystems rely on the characteristics.
conversion of solar energy into ƒ Biological evolution is observable as
chemical energy for use in biological phenotypic changes in a population
processes. over multiple successive generations.
ƒ The dependence on the availability ƒ Speciation, extinction, and the
of abiotic and biotic resources results abundance and distribution of
in complex and dynamic interactions organisms occur in response to
between organisms and populations. environmental conditions.
ƒ Changes to the environment can alter
interactions between organisms.

Unit 3: Cellular Systems (CELLS) Unit 4: Genetics (GEN)

ƒ Four classes of macromolecules serve ƒ The molecular structure of DNA

as the primary building blocks of enables its function of storing life’s
biological systems. genetic information.
ƒ Biological systems have specialized ƒ Encoded in DNA is the heritable
structures that enable specific information responsible for
functions necessary to sustain life. synthesis of RNA, which makes gene
ƒ Biological systems must respond expression possible.
to changes in internal and external ƒ Organisms have diverse strategies for
environments in order to maintain passing their genetic material on to
dynamic homeostasis. the next generation.
ƒ In order to sustain complex ƒ Models can be used to illustrate and
processes, biological systems must predict the inheritance of traits.
have mechanisms for growth and
repair.

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Pre-AP Biology Course Framework

Unit 1: Ecological Systems

Suggested Timing: Approximately 5 weeks

In this unit, students deepen and expand prior knowledge, gained in a middle school
life science course, of how the cycling of matter and flow of energy regulate ecosystems.
Students also apply proportional reasoning skills to examine data, especially bivariate
data, in order to analyze and make scientific claims about patterns, relationships, and
changes in the structure and distribution of ecological populations and communities.
This unit provides students an opportunity to build on and deepen their understanding
of the living and nonliving components that regulate the structure and function of
ecological systems. Students should begin to gain an appreciation for the intricate
and often fragile interdependent relationships that ecological communities rely on.
Students also explore how communities change over time, both through naturally
occurring processes and through human activities.

ENDURING UNDERSTANDINGS
Students will understand that …

ƒ Biological systems depend on the cycling of matter within and between Earth’s
systems.
ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

KEY CONCEPTS
ƒ ECO 1: Cycling of Matter in the Biosphere
ƒ ECO 2: Population Dynamics
ƒ ECO 3: Defining Ecological Communities
ƒ ECO 4: Ecological Community Dynamics
ƒ ECO 5: Changes in Ecological Communities

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Pre-AP Biology Course Framework

KEY CONCEPT ECO 1: CYCLING OF MATTER IN THE BIOSPHERE

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Hydrologic Cycle

ECO 1.1(a) Explain how the unique properties and ECO 1.1.1 Water cycles between abiotic and biotic systems in
phase changes of water enable and regulate biological a process known as the hydrologic cycle.
reactions and/or processes. a. The polar nature of water results in properties on which
ECO 1.1(b) Create and/or use a model to explain how biological systems depend, such as dissolving organic and
biological systems function in the hydrologic cycle as inorganic nutrients.
water is transferred, transported, and/or stored. b. The hydrologic cycle is driven by energy from the sun and
gravity.
c. The largest reservoir of water in the global hydrologic cycle
is the world’s oceans.
d. Only a small portion of the water on Earth is fresh water,
which is required for life by all terrestrial organisms,
including humans.

Carbon and Nutrient Cycles

ECO 1.2(a) Explain the importance of the cycling of ECO 1.2.1 Elements that are building blocks of
carbon for biological systems. macromolecules are transported from abiotic to biotic
ECO 1.2(b) Create and/or use models to illustrate how systems through gaseous and sedimentary cycles.
organisms’ capture and use of energy plays a role in a. The carbon cycle is a series of molecular transformations
the cycling of carbon in ecosystems. that includes photosynthesis and cellular respiration.
ECO 1.2(c) Explain the importance of the cycling of b. The nitrogen cycle is a series of transformations that
nutrients for biological systems. includes the conversion of nitrogen gas (the largest
ECO 1.2(d) Create and/or use models to describe reservoir of nitrogen on Earth) into biologically available
the cycling of nitrogen between biotic and abiotic nitrogen-containing molecules (e.g., nitrates).
systems. c. Phosphorus is a critical element for organisms, as it helps
make up numerous biomolecules (e.g., ATP, DNA).

Content Boundary: An understanding of the cycling of sulfur and phosphorus in the ecosystem is beyond the scope of
this course. Students should understand why phosphorus is an important element, as it serves as a monomer in many
important biomolecules (e.g., ATP, DNA), but the understanding of the cycle will not be assessed. Also, students should
be able to model the nitrogen cycle from a general standpoint of how biotic and abiotic components interact and depend
on one another. However, an understanding of all the chemical conversions during this cycle is beyond the scope of this
course.

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Pre-AP Biology Course Framework

KEY CONCEPT ECO 2: POPULATION DYNAMICS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Population Structure

ECO 2.1(a) Explain the role abiotic and/or biotic ECO 2.1.1 Species live in a defined range of abiotic and biotic
resources play in defining the niche of a species. conditions, or niche.
ECO 2.1(b) Collect and/or use data to predict a. Sunlight serves as the primary energy input for most
population size, density, and/or distribution. ecosystems.
ECO 2.1(c) Create and/or use models to illustrate how b. Species have a range of tolerance for abiotic resources and
environmental changes can alter the availability of conditions (e.g., sunlight, nutrients, pH, temperature).
biotic and/or abiotic resources. c. Biotic conditions, such as the behavior of social groups or
intraspecific competition for mates and food, also influence
population structure.
d. Environmental changes can alter the availability of abiotic
and biotic resources and conditions (e.g., climate changes,
drought, fire, floods).

Population Growth

ECO 2.2(a) Use data to explain the growth of a ECO 2.2.1 Population growth patterns are influenced by the
population. availability of resources and the interactions that occur within
ECO 2.2(b) Explain the relationship between resource and between populations of species.
availability and a population’s growth pattern. a. All organisms have the potential for exponential growth, but
ECO 2.2(c) Explain how competition for resources few organisms demonstrate this growth pattern.
shapes populations. b. Both density-dependent (e.g., nutrients and food) and
density-independent (e.g., weather, natural disasters) factors
regulate population growth.
c. The availability of a single resource may limit the survival of
an organism or population (e.g., nitrates in soil are a limiting
factor for plant growth).
d. Due to dynamic resource availability, many populations
fluctuate around their carrying capacity, thus demonstrating
a logistical growth pattern.
ECO 2.2.2 Populations demonstrate diverse growth strategies.
a. r-selected species are typically short-lived. Therefore,
they invest energy in producing many offspring during
reproduction but provide little to no care for those offspring.
b. K-selected species typically live longer. Therefore, they have
fewer offspring during reproduction but invest energy in the
care of those offspring to ensure survival.

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Pre-AP Biology Course Framework

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Food Webs and Transfer of Energy in Ecosystems

ECO 2.3(a) Create and/or use models to explain ECO 2.3.1 Energy availability helps shape ecological
the transfer of energy through the food web of a communities.
community. a. Typically, only 10 percent of the total energy in a given
ECO 2.3(b) Analyze data about species distributions trophic level is available to organisms in the next higher
to make predictions about the availability of resources. trophic level.

ECO 2.3(c) Make predictions about the energy b. The metabolic activity required to utilize the energy available
distribution in an ecosystem based on the energy in any given trophic level results in a loss of thermal energy
available to organisms. to the environment, as heat.
c. The energy available to organisms decreases from lower-
order trophic levels (primary producers) to higher-order
trophic levels (tertiary consumers).

Content Boundary: Students should begin to gain a conceptual understanding of how populations grow (e.g., exponential
versus logistical growth). However, many students may not be able to distinguish the subtle mathematical differences
between these two growth curves, especially in early generations. Therefore, assessment questions about growth
patterns will be limited to what influences these types of growth; calculations of growth curves are beyond the scope of
this course.
Cross Connection: Students should have strong familiarity with food webs from middle school life science. This course
should give students opportunities to make connections and extend their understanding of characteristics of organisms
and food webs to deeper conceptual knowledge about how energy is transferred through diverse ecosystems.

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Pre-AP Biology Course Framework

KEY CONCEPT ECO 3: DEFINING ECOLOGICAL COMMUNITIES

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Importance of Biodiversity

ECO 3.1(a) Describe how ecological processes rely ECO 3.1.1 Reductions in local and global biodiversity can
on the biological diversity of the community. significantly alter the stability of ecosystem processes and
ECO 3.1(b) Given a specific biome, describe the services.
ecological services that are provided that benefit a. Biologically diverse ecological communities are more
humans. resilient to environmental changes.
b. Ecosystems rely on biological diversity to sustain necessary
processes, such as cycling of nutrients and transfer of
energy through food webs.
c. Diverse ecosystems provide many necessary services that
humans rely on, such as climate regulation, carbon storage,
filtration of drinking water, pollination, and flood/erosion
control.

Types of Ecological Communities

ECO 3.2(a) Describe differences in the abiotic and/ ECO 3.2.1 Terrestrial biomes are classified by geographic
or biotic factors that shape aquatic and terrestrial locations and the abiotic factors that shape the unique
communities. ecological communities.
ECO 3.2(b) Use data to make predictions about how a. Two major abiotic factors that help define terrestrial biomes
abiotic and/or biotic factors shape an ecological are climate (temperature, precipitation) and soil type.
community. b. Ecological communities in terrestrial biomes are shaped by
the availability and abundance of the abiotic factors in that
region.
ECO 3.2.2 Aquatic biomes can generally be classified
according to their salt concentrations: oceanic, brackish, and
freshwater.
a. Ecological communities in aquatic biomes are shaped by
water depth (amount of sunlight), salinity, temperature,
nutrients, and flow rates (currents).
b. Estuaries are brackish ecological communities, as they form in
areas where freshwater rivers meet the sea. Their ecological
communities are uniquely shaped by the ocean tides.
c. The three major freshwater communities are rivers/streams,
lakes/ponds, and freshwater wetlands.

Content Boundary: Students should gain an understanding of the type of abiotic and biotic components of ecosystems
that shape communities of living organisms. They should be able to describe how these components differ for terrestrial
and aquatic ecosystems. However, a deep knowledge of chemical regulatory processes (e.g., dissolved oxygen in aquatic
systems) is beyond the scope of this course.
Cross Connection: Students should connect key concepts of the carbon cycle from earlier in the unit to the importance of
ecosystems, such as forests and oceans, as reservoirs for carbon.

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Pre-AP Biology Course Framework

KEY CONCEPT ECO 4: ECOLOGICAL COMMUNITY DYNAMICS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Interspecific Competition

ECO 4.1(a) Explain how competition shapes ECO 4.1.1 Competition between species drives complex
community characteristics. interactions in ecosystems.
ECO 4.1(b) Use data to analyze how competition a. Predator and prey populations respond dynamically to each
influences niche-partitioning in an ecological other.
community. b. Keystone species have a dramatic impact on the structure
ECO 4.1(c) Create and/or use models to explain and diversity of ecological communities (e.g., trophic
predictions about the possible effects of changes cascade).
in the availability of resources on the interactions c. Competition will lead to the exclusion of all but one species
between species. when two or more species attempt to occupy the same
niche.
d. Niche-partitioning is a means of reducing competition for
resources.

Symbiosis

ECO 4.2(a) Describe what type of symbiotic ECO 4.2.1 Competition in ecosystems has led to symbiotic
relationship exists between two organisms. relationships where two or more species live closely together.
ECO 4.2(b) Explain how a symbiotic relationship a. Mutualistic relationships often form to provide food or
provides an advantage for an organism by reducing protection for both of the organisms involved.
one or more environmental pressures. b. Parasitic relationships benefit only one organism in the
relationship (the symbiont) and harm the host.
c. Commensalism is a kind of relationship that benefits only
one organism in the relationship (the symbiont); the host is
neither harmed nor helped.

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Pre-AP Biology Course Framework

KEY CONCEPT ECO 5: CHANGES IN ECOLOGICAL COMMUNITIES

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Natural Changes in Biodiversity

ECO 5.1(a) Explain how natural changes in the ECO 5.1.1 Ecosystem biodiversity is influenced by several
ecosystem affect ecosystem dynamics. naturally occurring factors that alter the environment.
ECO 5.1(b) Create and/or use models to make a. Changes in energy, nutrient, and niche availability influence
predictions about how changes in biodiversity affect an ecosystem’s biodiversity.
local ecosystems. b. Major disturbances (e.g., forest fires, hurricanes, volcanic
ECO 5.1(c) Analyze data to make predictions about the eruptions) initiate ecological succession.
effects on biodiversity in response to environmental c. Mass extinctions open new, available niches for colonization
changes. and therefore can have significant impacts on biodiversity
(e.g., the mammalian diversity explosion post-dinosaur
extinction, 65 million years ago).
d. Keystone species and ecosystem engineers (e.g., elephants,
beavers) dramatically affect biodiversity in the ecosystem.

Human-Induced Changes in Biodiversity

ECO 5.2(a) Use evidence to support the claim that ECO 5.2.1 Human activities (e.g., urbanization, farming, tree
changes in ecosystems have resulted from human harvesting) also alter availability of nutrients, food, and niches
activities. for species and therefore affect population and community
ECO 5.2(b) Given a human activity, predict the dynamics.
potential biological consequences for an ecosystem’s a. Human activities include anthropogenic climate change, the
biodiversity. introduction of invasive species, habitat destruction, and air/
ECO 5.2(c) Create and/or use models to design water pollution.
solutions that mitigate the adverse effects of a b. The effects of human-induced environmental changes
human-induced environmental change on the and their impact on species are the subject of a significant
biodiversity of an ecosystem. amount of current scientific research.

Content Boundary: There are numerous examples of human-induced changes to ecosystems. The focus here is on
identifying a few examples of how human activities affect interactions in ecological systems by reducing biodiversity.
Understanding topics such as desertification and salinization resulting from human activity are beyond the scope of this
course.

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Pre-AP Biology Course Framework

Unit 2: Evolution
Suggested Timing: Approximately 4 weeks

In this unit, students explore the diverse types of data and multiple lines of evidence
that have informed our understanding of the theory of evolution over time. Students
should have a general familiarity with concepts associated with evolution from middle
school life science. This course is designed to build on that general understanding
to provide a foundation in the mechanisms of evolution. This includes both small-
scale evolution (changes in the relative frequency of a gene in a population from
one generation to the next) and large-scale evolution (speciation events over many
generations).

ENDURING UNDERSTANDINGS
Students will understand that …

ƒ The theory of evolution states that all organisms descend from a common ancestor
and share some characteristics.
ƒ Biological evolution is observable as phenotypic changes in a population over
multiple successive generations.
ƒ Speciation, extinction, and the abundance and distribution of organisms occur in
response to environmental conditions.

KEY CONCEPTS
ƒ EVO 1: Patterns of Evolution
ƒ EVO 2: Mechanisms of Evolution
ƒ EVO 3: Speciation

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Pre-AP Biology Course Framework

KEY CONCEPT EVO 1: PATTERNS OF EVOLUTION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Theory of Evolution

EVO 1.1(a) Use scientific evidence to justify a claim of EVO 1.1.1 The theory of evolution states that the unity and
an evolutionary relationship between species. diversity of life we see today is the result of more than 3.5
EVO 1.1(b) Describe shared characteristics billion years of evolutionary processes on Earth.
(homologies) among organisms that provide evidence EVO 1.1.2 Scientists use various sources of evidence to
for common ancestry. establish evolutionary relationships between organisms.
a. Fossil evidence, in conjunction with relative and radiometric
dating, provides insight into the geographic and temporal
distribution of species throughout Earth’s history.
b. Comparisons of anatomical and molecular homologies are
used to determine the degree of divergence from a common
ancestor.
1. The structure and function of DNA is a homology that
links all living organisms across the three domains of
life—Archaea, Bacteria, and Eukarya.
2. Cellular structures across all living organisms are
strikingly similar.

Classifying Evolutionary Relationships

EVO 1.2(a) Create or use models to illustrate EVO 1.2.1 Evolutionary relationships between organisms can
evolutionary relationships. be modeled using cladograms and phylogenetic trees, which
EVO 1.2(b) Use models of evolutionary relationships show inferred evolutionary relationships among living things.
to describe and/or analyze how different species are a. Cladograms and phylogenetic trees can illustrate speciation
related. events.
b. These models of evolutionary relationships show tree-like
lineages that do not correlate to levels of complexity or
advancement.

Content Boundary: The intent is not for students to memorize a list of characteristics that show descent from a common
ancestor. Instead, the focus here is on a few powerful examples of this evidence—such as DNA and cellular structures—
that will help make discussions in Unit 3: Cellular Systems and Unit 4: Genetics more meaningful for students.
Cross Connection: Revisit these topics to connect key concepts of shared characteristics across all living organisms
as students explore the structure and function of DNA and cellular components in Unit 3: Cellular Systems and Unit 4:
Genetics.

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Pre-AP Biology Course Framework

KEY CONCEPT EVO 2: MECHANISMS OF EVOLUTION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Natural Selection Theory

EVO 2.1(a) Describe the scientific discoveries that EVO 2.1.1 Key discoveries made by several scientists
informed the theory of natural selection. contributed significantly to Darwin’s understanding of
biological evolution.
a. Several naturalists, such as Lamarck and Wallace,
contributed models of evolution that informed Darwin’s
theories.
b. Darwin’s ideas about evolution were influenced by the work
of geologists Hutton and Lyell, whose work highlighted
the slow-acting geological processes that shape Earth’s
features.

Selective Mechanisms

EVO 2.2(a) Describe how selective pressures in the EVO 2.2.1 Darwin’s theory of natural selection is that a
environment can affect an organism’s fitness. selective mechanism in biological evolution may lead to
EVO 2.2(b) Explain how selective pressures in the adaptations.
environment could cause shifts in phenotypic and/or a. Abiotic ecosystem components (e.g., nutrients) and biotic
allele frequencies. ecosystem components (e.g., predators) act as selective
EVO 2.2(c) Use data to describe how changes in the pressures.
environment affect phenotypes in a population. b. Favorable traits in a given environment lead to differential
EVO 2.2(d) Predict how allelic frequencies in a reproductive success, or fitness, and over time can produce
population shift in response to a change in the changes in phenotypic and/or allele frequencies.
environment. c. Heritable traits that increase an organism’s fitness are called
adaptations.
d. Over time, the relative frequency of adaptations in a
population’s gene pool can increase.
e. Patterns of natural selection can include phenomena such
as coevolution, artificial selection, and sexual selection.
EVO 2.2.2 Favorable traits are relative to their environment
and subject to change.
a. Changes in the environment happen both naturally (e.g.,
floods, fires, climate change) and through human-induced
activities (e.g., pollution, habitat destruction, climate
change).

Cross Connection: Revisit these topics in Unit 4: Genetics to connect key concepts involving genetic processes. Mutation
types in DNA sequence, replication errors, and the random nature of independent assortment can lead to phenotypic
variations on which natural selection can act. Also, connect key concepts to Unit 1: Ecological Systems. Changes in
resources (e.g., nutrients from biogeochemical cycles and predator–prey interactions) can act as selective pressures on
organisms.

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Pre-AP Biology Course Framework

KEY CONCEPT EVO 3: SPECIATION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Mechanisms of Speciation

EVO 3.1(a) Explain how geographic separation events EVO 3.1.1 Speciation occurs when populations of the same
can lead to the formation of new species. species are separated, resulting in reduced gene flow, which
EVO 3.1(b) Describe mechanisms that contribute to over time allows populations to become genetically distinct
reproductive separation that could lead to speciation. from one another.
a. Geographic separation: a physical barrier (e.g., rivers
changing course, glacial movement, continental drift).
b. Habitat specialization: niche differentiation from others in
the population.
c. Behavioral separation: different mating habits, times, or
locations from others in the population.
d. Mechanical separation: structural differences in sex
organs that make individuals within a population unable to
reproduce with one another.

Rates of Speciation

EVO 3.2(a) Describe factors that affect the rate of EVO 3.2.1 Rates of speciation and extinction have fluctuated
speciation. throughout Earth’s history in response to changing
EVO 3.2(b) Use evidence to support the claim that environmental conditions.
rates of speciation have varied throughout Earth’s a. Gradualism is a model of evolution whereby lineages
history. accumulate small genetic changes over time.
EVO 3.2(c) Explain how environmental change can b. Punctuated equilibrium indicates that periods of stability for
result in the extinction of a species. species can be punctuated with periods of rapid speciation,
or splitting of lineages.
c. Extinction events that occur simultaneously across
numerous species, within a relatively short period of
geologic time, are known as mass extinctions.
d. There have also been human-induced extinctions due to
overharvesting and/or changes in habitat (e.g., great auk,
passenger pigeon).

Content Boundary: Assessments will not require students to recall dates of major mass extinction events. Instead, the
focus here should be on a few diverse examples of evidence that illustrate scientists’ current understanding of the rate of
speciation and extinction and how that shapes biodiversity.

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Pre-AP Biology Course Framework

Unit 3: Cellular Systems

Suggested Timing: Approximately 10 weeks

Students are introduced to cellular structure and function in middle school life science.
Therefore, this unit deepens and expands students’ knowledge as they explore how
cellular structures function together to support a cellular system that grows and develops,
responds to a changing environment, and obtains and uses energy. Through concepts
of homeostasis, students should gain an appreciation for how interdependent cellular
structures are on one another to maintain proper cellular functions. Students then build
on their knowledge of cellular systems as they examine how specific structures participate
in the process of capturing, storing, and using energy to drive cellular processes. They
also connect their understanding of ecological roles of organisms, from Unit 1: Ecological
Systems, to the various types of cellular energy processes—photosynthesis, cellular
respiration, and fermentation. Concepts in the cellular systems unit may be difficult
for some students due to the microscopic, seemingly intangible nature of these ideas
and phenomena. One way this course addresses this challenge is through introducing
systems-based thinking early on, in Unit 1: Ecological Systems. Now, in Unit 3, students
are equipped to use systems-based thinking to develop productive analogies for cellular
systems, which can aid in comprehension.

ENDURING UNDERSTANDINGS
Students will understand that …
ƒ Four classes of macromolecules serve as the primary building blocks of biological
systems.
ƒ Biological systems have specialized structures that enable specific functions
necessary to sustain life.
ƒ Biological systems must respond to changes in internal and external environments
in order to maintain dynamic homeostasis.
ƒ In order to sustain complex processes, biological systems must have mechanisms
for growth and repair.

KEY CONCEPTS
ƒ CELLS 1: Chemistry of Life ƒ CELLS 5: Cell Growth and Division
ƒ CELLS 2: Cell Structure and Function ƒ CELLS 6: Photosynthesis
ƒ CELLS 3: Cell Transport and Homeostasis ƒ CELLS 7: Cellular Respiration and
ƒ CELLS 4: Organisms Maintaining Fermentation
Homeostasis

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Pre-AP Biology Course Framework

KEY CONCEPT CELLS 1: CHEMISTRY OF LIFE

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Biomolecules

CELLS 1.1(a) Differentiate between the major CELLS 1.1.1 The four classes of organic macromolecules are
macromolecules based on their structure and/or proteins, carbohydrates, lipids, and nucleic acids. Each class
function. has unique chemical structures.
CELLS 1.2(a) Explain the role macromolecules play in a. These organic macromolecules are primarily made up of just
supporting cellular function. a few elements—carbon, hydrogen, nitrogen, oxygen, sulfur,
and phosphorus.
b. Most macromolecules are polymers that are made up of
specific, smaller subunits called monomers.
CELLS 1.2.1 Each class of macromolecule carries out specific
functions in biological systems.
a. Carbohydrates serve as the primary source of energy for
organisms in the forms of glycogen and starch, and as
structural support in plant cell walls in the form of cellulose.
b. Lipids are used as a source of energy and as building blocks
of biological membranes.
c. Proteins are responsible for numerous cellular functions,
such as catalyzing reactions, providing structure, and aiding
in cell transport and signaling.
d. Nucleic acids are responsible for storing and transferring
genetic information in the form of DNA and RNA.

Enzymes

CELLS 1.3(a) Describe the effect of enzymes on the CELLS 1.3.1 Enzymes are proteins that are catalysts in
rate of chemical reactions in biological systems. biochemical reactions and essential for maintaining life
CELLS 1.3(b) Predict how a change in pH and/or processes.
temperature will affect the function of an enzyme. a. The rate of a chemical reaction is affected by the
concentration of substrates and enzymes.
b. Enzymes have specific shapes that bind to specific
substrates in a precise location called the active site.
c. Enzymes function optimally in a specific pH and temperature
range.

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Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Cellular Energy Requirements

CELLS 1.4(a) Explain the role of ATP in supporting CELLS 1.4.1 Cells transfer and use energy from a variety of
processes in biological systems. molecules in order to perform cellular functions.
CELLS 1.4(b) Explain why different species a. ATP is a high-energy molecule used in the cell to carry out
demonstrate diverse energy and nutrient many cellular processes.
requirements. b. The amount of energy available to organisms from the
CELLS 1.4(c) Use data to predict the energy breakdown of macromolecules varies based on their
requirements of diverse species. chemical composition.
CELLS 1.4.2 Because organisms have diverse ecological roles,
they also have diverse energy requirements.

Content Boundary: While students should recognize that sulfur is one of the most common elements in living systems, a
deeper understanding of the role sulfur plays in biological systems is beyond the scope of this course.
Deep understanding of bond energy is beyond the scope of this course. However, students should have a basic
understanding that in order to break any bond, energy must be absorbed. Conversely, in order to form any bond, energy
must be released. Therefore, energy is available to biological systems when more stable bonds are formed in chemical
reactions; the high-energy bonds in ATP are an example of this.
Cross Connection: Students should connect key concepts to Unit 1: Ecological Systems. The cycling of matter in the
biosphere provides the building blocks for development of macromolecules. Students should make connections between
the role of enzymes in biological systems and how those systems can be affected by mutations during replication—
specifically, when these mutations result in changes to enzymes produced during protein synthesis (Unit 4: Genetics).
Students should expand on that understanding to see how changes in proteins (enzymes) influence an organism’s fitness,
connecting to key concepts in Unit 2: Evolution.

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KEY CONCEPT CELLS 2: CELL STRUCTURE AND FUNCTION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Cell Structure and Function

CELLS 2.1(a) Provide evidence to support the claim CELLS 2.1.1 The cell is the basic unit of biological systems,
that all biological systems demonstrate some shared and there are some shared characteristics among all cells.
characteristics. a. All cells possess a plasma membrane, ribosomes, genetic
CELLS 2.2(a) Develop and/or use models to compare material, and cytoplasm.
and contrast cell structures of different cells. b. All cells result from the division of preexisting cells.
CELLS 2.2.1 Cells have specialized structures that perform
specific functions.
a. Some cells (eukaryotes) have a nucleus that houses their DNA.
b. Cell structures can be organized based on four primary
functions:
1. Energy transfer (e.g., chloroplasts, mitochondria).
2. Production of proteins (e.g., ribosomes, ER, Golgi apparatus).
3. Storage and recycling of materials (e.g., lysosomes,
vacuoles, vesicles).
4. Support and movement (e.g., cell walls, cytoskeleton,
flagella).

Specialized Cells

CELLS 2.3(a) Explain how cell structures in different CELLS 2.3.1 Multicellular organisms have specialized cells
types of organisms enable specialized cell functions. that perform a wide variety of functions.
CELLS 2.3(b) Describe how cell structures support an a. During development, cells become specialized and develop
organism’s ecological role. into higher-order systems (i.e., tissues, organs).
b. Specialized cells perform a wide variety of unique functions
for organisms (e.g., muscle cells, red blood cells).
CELLS 2.3.2 Cell structures can differ across organisms and
often give insight into an organism’s ecological role.
a. Prokaryotes lack a nucleus and membrane-bound
organelles, whereas eukaryotes possess a nucleus and
complex, membrane-bound organelles.
b. Within the Eukarya domain, cellular structures and functions
differ among organisms.
1. Plant cells have large, central vacuoles and chloroplasts
that enable photosynthesis.
2. Some cells have rigid cell walls (e.g., fungi, plants).

Content Boundary: Assessments will not require students to recall an exhaustive list of organelles and their functions.
Instead the focus is on how an organelle’s function sustains specific biological systems. Therefore, ideally, deeper
understanding of organelles is developed in context throughout the course based on their function (e.g., nucleus—genetic
processes, mitochondria—respiration, chloroplast—photosynthesis, ribosomes—protein synthesis, lysosomes—transport).

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KEY CONCEPT CELLS 3: CELL TRANSPORT AND HOMEOSTASIS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Cell Membrane Structure

CELLS 3.1(a) Explain how cell membranes function CELLS 3.1.1 Cells have phospholipid membranes that are
in maintaining dynamic homeostasis for biological selectively permeable.
systems. a. All cells have membranes that separate the cell from the
CELLS 3.1(b) Create and/or use models to explain the external environment; some cells also have a cell wall for
structure and function of cell membrane components. structure and protection.
b. Membranes consist of a phospholipid bilayer with numerous
proteins embedded within and across the surfaces of the
membrane.
c. Carbohydrate chains attach to some surface proteins,
and together they contribute to cell-to-cell chemical
identification.

Cell Transport

CELLS 3.2(a) Use data to investigate how various CELLS 3.2.1 Cells depend on the structure of the cell
solutes and/or solvents passively move across membrane to move materials into and out of the cell in order
membranes. to maintain dynamic homeostasis.
CELLS 3.2(b) Explain how materials move into or out a. Passive transport involves the movement of solutes across
of the cell across the cell membrane. the membrane along the concentration gradient, without the
CELLS 3.2(c) Create and/or use representations and/ use of additional energy.
or models to predict the movement of solutes into or b. Active transport involves the movement of solutes across
out of the cell. the membrane against their concentration gradients with the
use of additional energy.
c. Bulk transport of molecules across the membrane is
accomplished using endocytosis or exocytosis.

Cell Size and Diffusion

CELLS 3.3(a) Describe how the size of a cell affects its CELLS 3.3.1 Diffusion is most efficient when the surface area
ability to function efficiently. is high and the volume is low.
a. Small cell size creates a surface-area-to-volume ratio that
enables more efficient diffusion.
b. The surface-area-to-volume ratio gets smaller as the cell
gets larger.

Cross Connection: Students should make connections to key concepts from Unit 1: Ecological Systems. The cycling of
matter contributes to the type of materials that the cell will transport to sustain necessary functions and support cellular
energy processes.

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KEY CONCEPT CELLS 4: ORGANISMS MAINTAINING HOMEOSTASIS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Organ/Tissue Systems

CELLS 4.1(a) Describe how organ systems work CELLS 4.1.1 Multicellular organisms rely on tissues and organ
together to maintain homeostasis. systems to transport nutrients and waste in order to maintain
CELLS 4.1(b) Predict the consequence of a disruption dynamic homeostasis.
in homeostasis. a. Animals have organ systems that work together to transport
nutrients and excrete waste.
1. The digestive system is needed to derive nutrients and
basic building blocks (monomers) from food, which are
required for cellular functioning and growth.
2. The respiratory system is needed for gas exchange to
obtain oxygen and remove carbon dioxide.
3. The circulatory system is needed to transport oxygen and
nutrients to cells.
4. The excretory system is needed to remove toxins and
nitrogenous wastes from the body and to maintain water
balance with the help of the circulatory system.
b. Plants have specialized vascular tissues and cells that
transport nutrients, water, and waste.
1. Plants depend on xylem to transport water and nutrients
for photosynthesis from the roots to the leaves and on
phloem to transport sugars from the leaves to the rest of
the plant.
2. Plants excrete waste products from photosynthesis
through the stomata in their leaves.

Response to Stimuli

CELLS 4.2(a) Describe the benefits associated with CELLS 4.2.1 Organisms have positive or negative responses
tropisms and/or taxes in organisms in response to an to external stimuli in their environment in order to maintain
external stimulus. dynamic homeostasis.
CELLS 4.2(b) Predict how an organism might respond a. Plants exhibit tropisms that determine direction of growth
to a change from the external environment in order to toward or away from a stimulus, such as light, chemicals,
maintain homeostasis. gravity, touch, and water.
b. Animals exhibit taxes that enable them to move in response
to a stimulus, such as food, light, or pH.

Content Boundary: It is not the intent for students to develop a deep understanding of body systems. The focus here
is on using a few key systems—digestive, respiratory, circulatory, and excretory—as a means to understanding how
systems work together to support overall functions in a multicellular organism. These systems help deepen students’
understanding about cellular energy, eliminating waste, and the role of diffusion in those processes. The nervous and
endocrine systems are beyond the scope of this course.
Content Boundary: Understanding of the role of hormones (e.g., auxin) in plant tropisms is beyond the scope of this course.

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KEY CONCEPT CELLS 5: CELL GROWTH AND DIVISION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Cell Cycle: Interphase

CELLS 5.1(a) Describe the importance of the growth CELLS 5.1.1 Generally, the cell spends 90 percent of its time in
phases in the cell cycle. interphase.
CELLS 5.1(b) Explain how the cell cycle is regulated. a. During the growth phases of interphase (G1 and G2) the cell
is producing new organelles and proteins. There are cell
division checkpoints at the end of both of these phases.
b. During the synthesis phase of interphase, DNA uncoils to
replicate itself. Afterward, each chromosome consists of two
double-stranded copies of identical DNA.

Cell Cycle: Cell Division

CELLS 5.2(a) Explain why chromosome duplication CELLS 5.2.1 Multicellular organisms use mitotic cell division in
must occur prior to mitotic division. order to replace dying or damaged cells.
CELLS 5.2(b) Create and/or use models to explain the a. Mitosis, the fourth phase of the cell cycle, consists of a
phases of mitosis. series of sub-phases (prophase, metaphase, anaphase,
CELLS 5.2(c) Predict consequences for biological and telophase) whereby the parent nucleus produces two
systems if cell cycle regulation is altered. genetically identical daughter nuclei.
b. There is a cell division checkpoint during metaphase.
c. Cancer cells form when cell division continues without
regulation.

Viruses

CELLS 5.3(a) Describe the structural differences CELLS 5.3.1 Viruses must utilize cellular machinery in
between viruses and cells. biological systems in order to replicate their genetic material.
CELLS 5.3(b) Explain how viruses affect functions in a. Viruses lack the ability to perform reactions that require
biological systems. energy, such as replicating their own genetic material.
b. Viruses bind to and release their genetic material into host
cells, which allows the cellular machinery to be hijacked to
produce viral proteins and genomes.
c. Viral infection may disrupt biological systems by
manipulating cell cycle regulation and altering the normal
synthesis of proteins, causing disease or cell death in
organisms.

Content Boundary: The focus on the cell cycle, including mitosis, is not on memorizing phases in the appropriate order,
but rather how those individual phases support other vital functions that sustain biological systems. Students should
see the need for cells to grow in size and increase the number of organelles prior to cellular division. They should also
understand why regulating cell size through mitotic division is necessary. This keeps cell sizes small in order to support
diffusion rates and improve efficiency of cellular processes.

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KEY CONCEPT CELLS 6: PHOTOSYNTHESIS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Photosynthesis

CELLS 6.1(a) Explain why the products of CELLS 6.1.1 Photosynthetic organisms have the cellular
photosynthesis are ecologically important. structures to absorb solar radiation and convert it into
CELLS 6.1(b) Create and/or use models to explain chemical energy.
the process of converting solar energy into chemical a. Photosynthetically active radiation wavelengths occur in the
energy through photosynthesis. visible light spectrum.
CELLS 6.1(c) Use data to describe what factors affect b. Photosynthetic organisms have specialized pigments,
rates of photosynthesis. membranes, and/or organelles that absorb solar radiation
and convert it into chemical energy.
c. Photosynthetic organisms rely on properties of water, such
as cohesion, adhesion, and surface tension, which result in
capillary action.
d. Photosynthesis is divided into two stages: light-dependent
and light-independent reactions.
1. Light-dependent reactions require sunlight energy and
H2O to transfer energy to ATP and NADPH. A byproduct of
this process is oxygen.
2. Light-independent reactions use CO2, ATP, and NADPH to
produce sugars.

Content Boundary: The intent is not for students to memorize details of chemical reactions that occur during
photosynthesis. Instead the focus here is on understanding the role of the main reactants and byproducts (as defined in
the essential knowledge) at each stage of energy transfer. A deep understanding of photosystems I and II and specific
steps of the Calvin cycle is beyond the scope of this course.

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KEY CONCEPT CELLS 7: CELLULAR RESPIRATION AND FERMENTATION

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Cellular Respiration

CELLS 7.1(a) Explain why the cellular energy CELLS 7.1.1 Cellular respiration is a series of enzymatic
processes in producers and consumers are reactions that utilize electron carrier molecules to synthesize
dependent on one another. ATP molecules.
CELLS 7.1(b) Create and/or use models to explain how a. Transfer of energy through cellular respiration begins with
consumers obtain usable energy from the products of the carbon compounds generated by producers during
photosynthesis. photosynthesis.
CELLS 7.1(c) Describe how consumers store the b. Glycolysis, an anaerobic process that occurs in the
energy acquired through cellular respiration. cytoplasm, uses glucose and two molecules of ATP to
produce NADH, pyruvic acid, and four molecules of ATP.
c. The Krebs cycle, an aerobic process that occurs in the
mitochondria, uses pyruvic acid to produce ATP and electron
carriers called NADH and FADH2. Carbon dioxide is produced
as a waste product during these chemical reactions.
d. The electron transport chain transfers the high-energy
electrons from NADH and FADH2 to oxygen, producing H2O.
e. The build-up of hydrogen ions in the inner mitochondrial
space produces a gradient that allows the production of
36–38 ATP molecules from each glucose molecule.

Fermentation

CELLS 7.2(a) Explain the biological importance of CELLS 7.2.1 Organisms have processes for the transfer of
fermentation. energy under completely anaerobic conditions.
CELLS 7.2(b) Describe how energy transfer in the cell a. Fermentation allows for production of two molecules of ATP
occurs under anaerobic conditions in consumers. during glycolysis if no oxygen is present.
b. Two common forms of fermentation are alcohol and lactic acid.
1. Yeast uses alcohol fermentation to transfer energy from
glucose and to release CO2 as a byproduct. This is an
economically important process because it is used to
make many food products.
2. Bacterial and animal cells are able to utilize lactic acid
fermentation to transfer energy from glucose in the
absence of oxygen.

Content Boundary: The focus for this key concept is on the understanding of how the products from photosynthesis enable
the process of cellular respiration. It is more important for students to be able to use reactants and products to explain the
interdependence between photosynthesis and cellular respiration than to memorize a series of steps that occur during these
processes.
Cross Connection: In discussing electron transport chain processes whereby intermembrane proteins (enzymatic) allow
movement of hydrogen ions, students should make connections to key concepts involving the role of proteins, membrane
structures, and diffusion from earlier in this unit.

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Unit 4: Genetics
Suggested Timing: Approximately 9 weeks

Similar to the study of cellular systems, many key concepts in genetics can be
somewhat abstract for students because they are on a scale that cannot be seen with
the eye. Therefore, in order to better visualize genetic processes, such as DNA and
protein synthesis, in this unit students engage with models, diagrams, and computer
simulations. Students build on prior basic understanding of the passing of traits, from
middle school life science, by developing a strong foundational understanding of the
molecular processes responsible for the passing of traits. They also use mathematics
and pedigree models to analyze and predict inheritance patterns, and explore current
biotechnology associated with the study and manipulation of genes.

ENDURING UNDERSTANDINGS
Students will understand that …

ƒ The molecular structure of DNA enables its function of storing life’s genetic
information.
ƒ Encoded in DNA is the heritable information responsible for synthesis of RNA,
which makes gene expression possible.
ƒ Organisms have diverse strategies for passing their genetic material on to the next
generation.
ƒ Models can be used to illustrate and predict the inheritance of traits.

KEY CONCEPTS
ƒ GEN 1: Structure of DNA
ƒ GEN 2: DNA Synthesis
ƒ GEN 3: Protein Synthesis
ƒ GEN 4: Asexual and Sexual Passing of Traits
ƒ GEN 5: Inheritance Patterns
ƒ GEN 6: Biotechnology

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KEY CONCEPT GEN 1: STRUCTURE OF DNA

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Race to Discover DNA

GEN 1.1(a) Explain how models of DNA changed over GEN 1.1.1 Several scientists’ models of DNA contributed to
time as new scientific evidence emerged, resulting in the final consensus model of DNA’s structure produced by
the final consensus model. Watson and Crick.
a. Chargaff observed 1:1 ratios between certain nitrogenous
bases in DNA’s nucleotides (A-T, G-C).
b. Franklin’s work showed that DNA was in the shape of a helix
and suggested that the nitrogenous bases were near the
center.
c. Watson and Crick built the consensus model of DNA known
today.

The Structure of DNA

GEN 1.2(a) Describe how DNA is organized differently GEN 1.2.1 DNA is the genetic material found in all living
in prokaryotes and eukaryotes. organisms.
GEN 1.2(b) Describe the monomers necessary for a. Living systems obtain the monomers, such as nitrogen, to
cells to build DNA. build DNA strands using products from metabolic reactions.
b. In prokaryotes, genomic DNA is organized into a single,
circular chromosome.
c. In eukaryotes, genomic DNA is organized into multiple, linear
chromosomes found in the nucleus.
1. DNA is a double helix with the two strands running in
opposite directions (antiparallel).
2. Nitrogenous base pairing occurs in between the two
strands, each of which contains a sugar–phosphate
backbone.

Content Boundary: Assessments will not require students to recall a list of scientists and their contributions to the
discovery of the structure of DNA. The focus here is on how scientific knowledge (e.g., work from Pauling, Chargaff,
Franklin, Watson, and Crick) developed over time, finally leading to the understanding of the consensus model of DNA.
Cross Connection: Connect key concepts from the cycling of matter in the biosphere (Unit 1: Ecological Systems) and the
chemistry of life (Unit 3: Cellular Systems) to help students understand where the building blocks to make these nucleic
acids (both DNA and RNA) come from.

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KEY CONCEPT GEN 2: DNA SYNTHESIS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

DNA Synthesis (Replication)

GEN 2.1(a) Describe the importance of DNA synthesis. GEN 2.1.1 All living cells have a mechanism for DNA synthesis
GEN 2.1(b) Create and/or use models to explain how (replication) in order to pass on genetic information to new
DNA synthesis occurs. cells.
GEN 2.1(c) Explain the function of enzymes in DNA a. Each of the two strands of DNA serves as a template for a
synthesis. new complementary strand in a semiconservative process
of replication.
b. DNA helicase and DNA polymerase are the primary enzymes
required for the replication process.

Content Boundary: Understanding of in-depth DNA replication processes, such as formation of leading and lagging
strands, Okazaki fragments, and DNA polymerase working in the 5’-to-3’ direction, is beyond the scope of this course.

KEY CONCEPT GEN 3: PROTEIN SYNTHESIS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

RNA Structure

GEN 3.1(a) Explain structural differences between GEN 3.1.1 The unique structure of RNA enables its function in
RNA and DNA. protein synthesis.
a. Types of RNA may vary in structure, but they all have
important structural differences from DNA:
1. All types of RNA contain the sugar ribose instead of
deoxyribose.
2. All types of RNA contain the nitrogen base uracil instead
of thymine.
3. mRNA is single-stranded instead of double-stranded like
DNA.

RNA Transcription

GEN 3.2(a) Describe how heritable information stored GEN 3.2.1 RNA synthesis, or transcription, results in three
in DNA is transferred to RNA through transcription. forms of the polymer.
a. RNA synthesis occurs in the cytoplasm of prokaryotes and
in the nucleus of eukaryotes.
b. During transcription, a single strand of DNA is used as a
template to synthesize a complementary strand of RNA.
c. RNA transcription results in the synthesis of messenger RNA
(mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

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Translation

GEN 3.3(a) Explain the role of mRNA in protein GEN 3.3.1 Gene expression includes the process of protein
synthesis. synthesis, which requires transcribing heritable information
GEN 3.3(b) Identify the role of amino acids in protein stored in DNA and translating it into polypeptides.
synthesis. a. Genes are certain sections of DNA on chromosomes that
GEN 3.3(c) Create and/or use models to demonstrate contain the instructions for making specific proteins,
how the information in genes is expressed as proteins. and make up an organism’s genotype and determine its
GEN 3.3(d) Explain how the structure of DNA relates to phenotype.
an organism’s phenotype and genotype. b. Information carried on genes in the template strand of DNA
is transcribed into a strand of mRNA during transcription.
c. Translation of mRNA into the sequence of amino acids
(protein) occurs with the help of ribosomes in the cytoplasm.
1. mRNA is read by the ribosome three bases at a time (a
codon), which corresponds to a specific amino acid that the
ribosome incorporates into a growing polypeptide chain.
2. Translation begins and ends with specific start and stop
codons.
3. The particular sequence of amino acids determines the
shape and function of the expressed protein.

Mutations

GEN 3.4(a) Describe how changes in DNA sequences GEN 3.4.1 Mutations are heritable changes to DNA sequences.
may affect protein structure and function. a. Mutations are random changes in DNA sequences that
GEN 3.4(b) Create and/or use models to explain the may occur as a result of errors during replication or the
consequences of changes in DNA. effects of environmental mutagens (e.g., UV light, x-rays, and
GEN 3.4(c) Analyze data to make predictions about carcinogens).
how changes in DNA affect an organism’s phenotype. b. A change in a DNA sequence occurs when a nucleotide
is substituted into the original sequence (causing a point
mutation) or inserted into or deleted from the sequence
(causing a frameshift mutation).
c. Depending on how the changes impact gene expression,
mutations may cause negative disruption in gene and
protein function, have little to no effect on organisms, or
produce beneficial variation.

Content Boundary: It is important for students to realize that all forms of RNA are made from DNA and to understand how
forms of RNA work together to make proteins. However, assessments will not require students to recall a step-by-step list
of the process. Instead, they should focus on how the structure of each form of RNA fits its role in protein synthesis and
why this process is important (for how genotypes determine phenotypes). Students should understand that only some
regions of DNA carry genetic information for proteins (genes). However, specifics about introns and exons are beyond the
scope of this course.
Cross Connection: Make connections to key concepts from Unit 2: Evolution of how mutations serve as sources of
genetic variation on which natural selection mechanisms work.

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KEY CONCEPT GEN 4: ASEXUAL AND SEXUAL PASSING OF TRAITS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Asexual Reproduction

GEN 4.1(a) Explain why asexual reproductive GEN 4.1.1 Most unicellular and some multicellular organisms
strategies do not lead to genetic diversity. can reproduce through asexual processes that do not
GEN 4.1(b) Explain the advantage(s) of asexual increase genetic variation in the population.
reproduction strategies for organisms. a. Binary fission is a form of asexual cell division that results in
a symmetrical genetic clone of the parent cell (e.g., bacteria,
amoebas).
b. Budding is a form of asexual cell division that results in a
diploid, asymmetrical genetic clone of the parent cell (e.g.,
corals, yeast).
c. Some forms of parthenogenesis are a form of asexual
reproduction in some species, where offspring are produced
by females without the genetic contribution of a male (e.g.,
bees, lizards, sharks).
d. Asexual reproduction can be performed without the need to
find mates and can lead to rapid proliferation of a population
over time.

Sexual Reproduction (Meiosis)

GEN 4.2(a) Explain why reduction division must occur GEN 4.2.1 Some unicellular and most eukaryotic organisms
to produce gametes. reproduce sexually, requiring a process called meiosis that
GEN 4.2(b) Explain how meiotic cellular division results in genetic variation in the population.
followed by fertilization leads to genetic diversity a. Meiotic division requires two distinct nuclear divisions in
within a population. order to reduce one diploid (2N) cell into four haploid (N)
GEN 4.2(c) Create and/or use models to explain how cells.
chromosome number is halved during meiosis. 1. During the first division in meiosis, homologous
chromosomes pair together in a tetrad and crossing-over
occurs, which increases genetic variation.
2. At the end of the first division (meiosis I), homologous
chromosomes are separated and two daughter cells are
formed.
3. At the end of the second meiotic division (meiosis II),
the two cells are separated into four genetically diverse
haploid cells, which in animals differentiate into gametes.
b. Sexual reproduction occurs via fertilization, when sperm and
egg gametes fuse and form a zygote, restoring the diploid
number of chromosomes.

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Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Chromosomal Disorders

GEN 4.3(a) Describe how some organisms have GEN 4.3.1 Chromosomal disorders occur when the structure
structurally altered chromosomes in their genome. or number of chromosomes has been altered, which often
GEN 4.3(b) Predict how altered chromosome numbers impairs normal function and development in organisms.
may affect organisms. a. Unequal crossing-over events can lead to chromosomal
disorders.
b. Random nondisjunction events may occur in meiosis when
chromosomes fail to separate. This may result in viable
offspring with an abnormal number of chromosomes.

Content Boundary: Students will not be assessed on the molecular details of the asexual reproductive strategies
of budding and binary fission, nor on which organisms utilize asexual reproduction. The focus here is on how this
reproductive strategy leads to the genetic clone of the parent cell, the impact on gene pool diversity, and why that process
is advantageous for the organism at that time.
Cross Connection: Students should make connections to key concepts in Unit 1: Ecological Systems and Unit 2:
Evolution, recognizing how changes in the environment and natural selection act on variation in traits that emerge through
meiosis. These processes lead to phenotypic variation in species and populations.

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 About the Course

Pre-AP Biology Course Framework

KEY CONCEPT GEN 5: INHERITANCE PATTERNS

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

Inheritance Patterns

GEN 5.1(a) Explain the relationship between genotype GEN 5.1.1 Investigation of Mendelian, or single-gene, traits
and phenotype. reveals the basis for understanding patterns of inheritance.
GEN 5.1(b) Describe the type of inheritance pattern a. Many of an organism’s traits (phenotype) are determined by
based on data and/or use of models. the organism’s genes (genotype), which are passed from one
generation to the next.
b. Somatic cells of sexually reproducing organisms have two
copies of each gene (one inherited from each parent).
c. Each gene copy may have variants called alleles.
d. If present, dominant alleles are expressed, whereas
recessive alleles are expressed only in the absence of a
dominant allele.
GEN 5.1.2 Most traits do not follow Mendelian inheritance
patterns.
a. Some traits are determined by genes on sex chromosomes,
and some are influenced by environmental factors.
b. Most of our traits involve the interactions of multiple genes.
1. Codominance occurs when both alleles of homologous
chromosomes are fully expressed.
2. Incomplete dominance occurs when neither of the alleles
from a homologous chromosome pair are completely
dominant.

Predicting Inheritance

GEN 5.2(a) Create and/or use models to analyze the GEN 5.2.1 The inheritance of certain traits from parents to
probability of the inheritance of traits. offspring can be predicted using models.
GEN 5.2(b) Predict the inheritance of traits that do not a. Rules of probability can be applied to make predictions
follow Mendelian patterns. about the passage of alleles from parent to offspring using
GEN 5.2(c) Use a pedigree to predict the inheritance of mathematical models (Punnett squares).
a trait within a family. b. Pedigrees are useful tools for modeling inheritance patterns
to examine and/or make predictions about inheritance of a
specific trait from one generation to the next.

Content Boundary: Students will be expected to know non-Mendelian inheritance patterns, such as codominance and
incomplete dominance. However, epistatic genes are beyond the scope of this course.

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Pre-AP Biology Course Framework

KEY CONCEPT GEN 6: BIOTECHNOLOGY

Learning Objectives Essential Knowledge

Students will be able to … Students need to know that …

GEN 6.1(a) Use data to examine inheritance and/or GEN 6.1.1 Biotechnology enables scientists to study and
chromosomal disorders. engineer heritable traits of organisms.
GEN 6.1(b) Describe techniques used to manipulate a. Karyotypes are used to examine inheritance and help
DNA. identify and predict possible chromosomal genetic
GEN 6.1(c) Explain potential benefits and/or disorders.
consequences of manipulating DNA of organisms. b. Diverse methods, including PCR, gel electrophoresis, and
DNA profiling, are used to study organisms’ DNA.
c. Genetic engineering techniques (e.g., cloning, GMOs) can
manipulate the heritable information of DNA, resulting in
both positive and negative consequences.

Content Boundary: Students will not be assessed on a deep understanding of the molecular processes for manipulating
DNA. Instead the focus should be on giving a high-level understanding of common processes that allow development
of appropriate quantities of DNA to be studied and manipulated. Also, students should learn about exciting new
advancements in this field.

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 About the Course

Pre-AP Biology Model Lessons

Model lessons in Pre-AP Biology are developed in collaboration with biology educators
across the country and are rooted in the course framework, shared principles, and areas
of focus. Model lessons are carefully designed to illustrate on-grade-level instruction.
Pre-AP strongly encourages teachers to internalize the lessons and then offer the
supports, extensions, and adaptations necessary to help all students achieve the lesson
goals.

The purpose of these model lessons is twofold:

ƒ Robust instructional support for teachers: Pre-AP Biology model lessons are
comprehensive lesson plans that, along with accompanying student resources,
embody the Pre-AP approach to teaching and learning. Model lessons provide clear
and substantial instructional guidance to support teachers as they engage students
in the shared principles and areas of focus.
ƒ Key instructional strategies: Commentary and analysis embedded in each lesson
highlight not just what students and teachers do in the lesson, but also how and
why they do it. This educative approach provides a way for teachers to gain unique
insight into key instructional moves that are powerfully aligned with the Pre-AP
approach to teaching and learning. In this way, each model lesson works to support
teachers in the moment of use with students in their classroom.
Teachers have the option to use any or all model lessons alongside their own locally
developed instructional resources. Model lessons target content areas that tend to be
challenging for teachers and students. While the lessons are distributed throughout
all four units, they are concentrated more heavily in the beginning of the course
to support teachers and students in establishing a strong foundation in the Pre-AP
approach to teaching and learning.

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Pre-AP Biology Model Lessons

SUPPORT FEATURES IN MODEL LESSONS

The following support features recur throughout the Pre-AP Biology lessons, to
promote teacher understanding of the lesson design and provide direct-to-teacher
strategies for adapting lessons to meet their students’ needs:

Instructional Rationale
ƒ Meeting Learners’ Needs
Guiding Student Thinking Classroom Ideas

Key Concept ECO 4: Ecological Community Dynamics

Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects

To begin this lesson, engage students in a whole-class

guided reading and discussion of a short passage about
Meeting Learners’ Needs
UNIT 1
Meeting Learners’ Needs:
Some students may
coral bleaching adapted from NOAA (see the top of
Handout 1.8: Examining Coral Bleaching). This
passage helps establish context for the subsequent
struggle with some of
the words in the opening Optional differentiation strategies
text, such as symbiotic or
passage from a research article. Discussion may also
unearth student questions or unfamiliar terms that
zooxanthellae. It will be
necessary to help students to address diverse learning needs,
should be clarified prior to data analysis. define these words prior

ƒ Next, have students independently read the Coral

to examining the data.
such as ideas for just-in-time skill
Bleaching Study summary on the handout and
closely observe and analyze the data in the graphs. building during a lesson or ways to
Instructional Rationale: Instructional Rationale
break a task into smaller tasks, if
This lesson is designed to have students think like scientists, as they must extract and

Insight into the strategic synthesize information both from a reading and from a data display. It is important to
Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects
give students plenty of time to really sit with the data and make observations prior to needed, to make it more accessible.
Unit 1: Ecological Systems
moving into making analytical inferences.
design and purpose of
the instructional choices, HANDOUT
1.8 2004 3%
2007
Types of Coral
10% Bleached

flow, and scaffolding

18% 23%
9% Brain
35%
Staghorn
5% 13%

within the model lesson.

Finger
26%
Tree
25% 14%
19% Crystal

Rationales often describe Adapted from Zaki (student researcher), “Resilience of a Red Sea Fringing Coral Reef Under Extreme
Environmental Conditions: A Four Year Study.” © 2008 by the American Museum of Natural History.

how a concept is continued Handout 1.8

Check Your Understanding

later in the lesson or unit. ƒ Engage students in a whole-class
Key Concept
data. Prompts
discussion
ECO 5: Changes of theirCommunities
in Ecological
to promote student thinking may include:
initial observations about the
Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree Snakes in Guam
1. Describe the ecological relationship between the coral and the zooxanthellae algae.
u What similarities and differences do you notice first between the two data
Coral and the algae zooxanthellae are symbiotic with each other. The algae provide
collections?
the coral with nutrients to grow. (Note: At this point students are being introduced
u What does
to the idea ofa 1symbiosis,
UNIT
recorded percentage
so itStudents formay
a species
is not importantbefor in thetodata
familiar
them with set actually
invasive
identify mean?
species
mutualism or that live in their area or with invasive
speciesHowever,
what the algae is gaining in return. that areyou
more common,
could or “famous,”
extend this across the globe. This lesson is designed
question during
discussion.) to have students apply Key Concept ECO 4:Pre-APEcological
Biology Community
TEACH Dynamics to a
Teacher Resource 59
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common
2. How many quadrats were needed ecological
to examine problem,
the percent the introduction
coverage of the coral of invasive species, to explore how
ecological
species across the 18 m 2 covered duringprocesses may
the transect be altered
of the reef? through human activity. Students use textual and
graphical evidence from clue cards to form inferences about the ecological impact
1.5 m(1.5 m) = 2.25 m 2 ; 18 m 2 /2.25 m 2 = 8 quadrats
of the invasive brown tree snake.
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EXPLORING IMPACTS OF AN INVASIVE SPECIES
(18 m2) in 2007?

Classroom Ideas:
ƒ Show students a picture of an invasive brown tree
2 2 Classroom Ideas
10% = 0.1; 0.1(18 m ) = 1.8 m snake in Guam, such as the one below. Engage
It may be helpful to show
students in a brief discussion about invasive

Tips related to the logistics

4. If the percent of crystal coral coverage in 2007 remained constant for the entire a map of where Guam is
reef, how many square meters ofspecies. To help
crystal coral promote
coverage thinking
would about
you expect forinvasive
an located in relation to the
area of reef totaling 100 m2? species, the following prompts may be helpful: native regions of the brown

of the instruction, such as

u Why do you think the term invasive is used for tree snake (northeastern
10% = 0.1; 0.1(100 m 2) = 10 m 2 Australia, eastern
these species?
Indonesia, and Melanesia).
5. What percentage of the entire reefudid the scientists sample?

suggestions for alternative

How do these species get to new ecosystems?

Guiding Student Thinking: 18 m 2 /360 m 2 = 0.05(100) = 5%

Ways to facilitate productive

Pre-AP Biology 44 Student Resource
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student thinking and prevent or to alleviate pacing concerns.
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address student misconceptions Credit: Photo of Brown Tree Snake. © 2012 by Pavil Kirillov. CC BY 2.0. .

in critical areas of the lesson. Guiding Student Thinking

Some students may not realize that invasive species are species that have been
introduced into a new environment where they are not native organisms. In this
new environment, invasive species may have few if any natural predators and their
populations can increase rapidly. Sometimes, this rapid population increase can cause
ecological damage as well as economic problems. Students may not fully understand
that these same species in their native ecosystems are not invasive. Therefore, it may be
helpful to remind them that invasive species are also referred to as nonnative species.

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 About the Course

Pre-AP Biology Assessments for Learning

Pre-AP Biology assessments function as a component of the teaching and learning
cycle. Progress is not measured by performance on any single assessment. Rather,
Pre-AP Biology offers a place to practice, to grow, and to recognize that learning takes
time. The assessments are updated and refreshed periodically.

LEARNING CHECKPOINTS
Based on the Pre-AP Biology Course Framework, the learning checkpoints require
students to examine data, models, diagrams, and short texts—set in authentic
contexts—in order to respond to a targeted set of questions that measure students’
application of the key concepts and skills from the unit. All eight learning checkpoints
are automatically scored, with results provided through feedback reports that contain
explanations of all questions and answers as well as individual and class views for
educators. Teachers also have access to assessment summaries on Pre-AP Classroom,
which provide more insight into the question sets and targeted learning objectives for
each assessment event.

The following tables provide a synopsis of key elements of the Pre-AP Biology learning
checkpoints.

Format Two learning checkpoints per unit

Digitally administered with automated scoring and
reporting
Questions target both concepts and skills from the
course framework

Time Allocated Designed for one 45-minute class period per assessment

Number of Questions 11–14 questions per assessment

ƒ 9–12 four-option multiple choice
ƒ 2–5 technology-enhanced questions

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Pre-AP Biology Assessments for Learning

Domains Assessed

Learning Objectives Learning objectives within each key concept in the

course framework

Skills Three skill categories aligned to the Pre-AP science

areas of focus are assessed with regular frequency across
all eight learning checkpoints:
ƒ emphasis on analytical reading and writing
ƒ strategic use of mathematics
ƒ attention to modeling

Question Styles Question sets consist of two to three questions that

focus on a single stimulus or group of related stimuli,
such as texts, graphs, or tables.
Questions are set in authentic biological contexts.
Please see page 62 for a sample question set that illustrates
the types of questions included in Pre-AP learning
checkpoints and the Pre-AP final exam.

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Pre-AP Biology Assessments for Learning

PERFORMANCE TASKS
Each unit includes one performance-based assessment designed to evaluate the depth
of student understanding of key concepts and skills that are not easily assessed in a
multiple-choice format.

Performance tasks in the ecology and cellular systems units mirror the AP free-
response question style. Students demonstrate their understanding of content by
analyzing scientific texts, data, and models in order to develop analytical written
responses to open-ended questions.

Performance tasks in the evolution and genetics units actively engage students in
hands-on data analysis and modeling skills as they demonstrate their understanding of
key concepts in those two units.

Both types of performance tasks give students an opportunity to closely observe and
analyze real-world biological problems and apply the skills and concepts from across
the course units.

These tasks, developed for students across a broad range of readiness levels, are accessible
while still providing sufficient challenge and the opportunity to practice the analytical
skills that will be required in AP science courses and for college and career readiness.
Teachers participating in the official Pre-AP Program will receive access to online
learning modules to support them in evaluating student work for each performance task.

Format One performance task per unit

Administered in print
Educator-scored using scoring guidelines

Time Allocated Approximately 45 minutes or as indicated

Number of Questions An open-response task with multiple parts

Domains Assessed

Key Concepts Key concepts and prioritized learning objectives from

the course framework

Skills Three skill categories aligned to the Pre-AP science

areas of focus:
ƒ emphasis on analytical reading and writing
ƒ strategic use of mathematics
ƒ attention to modeling

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Pre-AP Biology Assessments for Learning

PRACTICE PERFORMANCE TASKS

Practice performance tasks in each unit provide students with the opportunity to
practice applying skills and knowledge in a context similar to a performance task,
but in a more scaffolded environment. These tasks include strategies for adapting
instruction based on student performance and ideas for modifying or extending tasks
based on students’ needs.
Performance Assessments At-a-Glance

Unit Performance Title Teacher Student

Assessment Access Access

Unit 1 Practice Termites, Teacher Student

Ecological Performance Guardians of Resources: Resources:
Systems Task the Soil Units 1 & 2 Unit 1

Performance Exploring Teacher-

Task Species distributed
Interactions handout
in the Great
Barrier Reef

Unit 2 Practice Tusklessness Teacher Student

Evolution Performance in African Resources: Resources:
Task Elephants Units 1 & 2 Unit 2

Performance The Flashy Teacher-

Task Guppy Data distributed
Analysis handout

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Pre-AP Biology Assessments for Learning

FINAL EXAM
Pre-AP Biology includes a final exam featuring multiple-choice and technology-
enhanced questions as well as an open-response question. The final exam is a
summative assessment designed to measure students’ success in learning and applying
the knowledge and skills articulated in the Pre-AP Biology Course Framework. The
final exam’s development follows best practices such as multiple levels of review by
educators and experts in the field for content accuracy, fairness, and sensitivity. The
questions on the final exam have been pretested, and the resulting data are collected
and analyzed to ensure that the final exam is fair and represents an appropriate range
of the knowledge and skills of the course.

The final exam is designed to be delivered on a secure digital platform in a classroom

setting. Educators have the option of administering the final exam in a single extended
session or two shorter consecutive sessions to accommodate a range of final exam
schedules.

Multiple-choice and technology-enhanced questions are delivered digitally and scored

automatically with detailed score reports available to educators. This portion of the final
exam is designed to build on the question styles and formats of the learning checkpoints;
thus, in addition to their formative purpose, the learning checkpoints provide practice
and familiarity with the final exam. The open-response question, modeled after the
performance tasks, is delivered as part of the digital final exam but is designed to be scored
separately by educators using scoring guidelines that are designed and vetted with the
question.

The following tables provide a synopsis of key elements of the Pre-AP Biology Final Exam.

Format Digitally administered

Questions target both concepts and skills from the
course framework
A scientific calculator feature is enabled on the platform,
but its use is not required.

Time Allocated One 105-minute session or two sessions of 60 minutes

and 45 minutes

Number of Questions 30–35 questions

ƒ four-option multiple-choice questions
ƒ technology-enhanced questions
ƒ one multipart open-response question

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Pre-AP Biology Assessments for Learning

Scoring ƒ automatic scoring for multiple-choice and

technology-enhanced questions
ƒ educator scoring for open-response question
ƒ comprehensive score reports with individual
student and class views for educators

Domains Assessed

Content Key concepts and prioritized learning objectives from

the course framework

Skills Three skill categories aligned to the Pre-AP science

areas of focus:
ƒ emphasis on analytical reading and writing
ƒ strategic use of mathematics
ƒ attention to modeling

Question Styles Question sets consist of two to three questions that

focus on a single stimulus or group of related stimuli,
such as texts, graphs, or tables.
Questions are set in authentic biological contexts.
Please see page 62 for a sample question set that illustrates
the types of questions included in Pre-AP learning
checkpoints and the Pre-AP final exam.

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Pre-AP Biology Assessments for Learning

SAMPLE ASSESSMENT QUESTIONS

The following questions are representative of what students and educators will
encounter on the learning checkpoints and final exam.

ANALYZING SCIENTIFIC DATA

Clostridium perfringens is a species of heterotrophic bacteria that is commonly

found consuming decaying organic matter in the sediments of freshwater lakes.
An investigation was conducted into the effect of temperature on growth of C.
perfringens. Researchers recorded the temperature of a 1-liter sample of lake
water and the concentration of bacteria in the water over a 30-day period. The
data are represented in the graph.
75 55
Bacteria concentration (ppm) Temperature (°F)

Bacteria concentration (ppm)

50
70
Temperature (°F)

45

65

40

60
35

55 30
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (days)

Examination of 1-liter samples of lake water over a 30-day period

1. Which of the following statements best describes the relationship between

temperature and growth of the bacterial population?
(A) Temperature has a direct effect on the growth of the bacterial population
since both the temperature and bacteria concentration are highest at day 30.
(B) Temperature has a negative effect on the growth of the bacterial population
since there are instances when temperature increases and bacteria
concentration decreases.
(C) Temperature is a limiting resource for the growth of the bacterial population
since the bacterial concentration line is nearly always above the temperature line.
(D) Resources other than temperature can limit the growth of the bacterial
population since there is not a direct correlation between water temperature
and bacteria concentration.

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Pre-AP Biology Assessments for Learning

Assessment Focus

Question 1 requires students to extract relevant information from a text, analyze

data, and use quantitative reasoning to construct an argument about the relationship
between an abiotic resource, light, and the growth of a population.
Correct Answer: D
Learning Objective:
ECO 2.2(b) Explain the relationship between resource availability and a population’s
growth pattern.
Area of Focus: Strategic Use of Mathematics

2. The biologists are interested in analyzing other environmental conditions that

may regulate the growth of the bacterial population. Which of the following is
the LEAST likely to affect the population growth of the bacteria in the lake?
(A) Amount of sunlight reaching the lake bottom
(B) Dissolved oxygen level in the lake
(C) Amount of decaying organic matter in the sediments
(D) pH of the lake water

Assessment Focus

Question 2 extends student thinking from the first question as it asks students to
demonstrate their understanding of the abiotic and biotic niche requirements for
heterotrophic organisms that may be responsible for the trends in data.
Correct Answer: A
Learning Objective:
ECO 2.2(a) Use data to explain the growth of a population.
Area of Focus: Emphasis on Analytical Reading and Writing

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Pre-AP Biology Assessments for Learning

USING A MODEL

The diagram represents a model of a typical food web from coastal waters in cool
temperate and subpolar seas, such as those around Antarctica. Use the model to
answer the following question.

Crabeater seal Killer whale

Squid
Adelie penguin
Leopard seal

Cod

Small animals
and protists
Krill
Algae

3. If cod were overfished in this Antarctic region and were not an available food
source, which of the following changes in the community is most likely to occur
as a result?
(A) The squid population will increase because there is reduced competition for
food.
(B) The killer whale population will increase because there are more leopard
seals.
(C) The crabeater seal population will decrease because there is a decrease in the
krill population.
(D) The squid population will decrease because there is a decrease in the algae
population.

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Pre-AP Biology Assessments for Learning

Assessment Focus

Question 3 assesses students’ ability to use a model to make predictions about how
the flow of energy through this food web would change if organisms are depleted.
Students must also apply their understanding of ecological roles (e.g., primary
consumers) and community dynamics (e.g., competition for food) at each trophic
level in order to make this prediction.
Correct Answer: A
Learning Objectives:
ECO 2.3(a) Create and/or use models to explain the transfer of energy through the
food web of a community.
ECO 2.3(c) Make predictions about the energy distribution in an ecosystem based on
the energy available to organisms.
Area of Focus: Attention to Modeling

DATA ANALYSIS

Duckweeds are small aquatic plants that live in freshwater ponds and streams
throughout North America. Scientists conducted an experiment to determine
how two different species of duckweed, Lemna polyrrhiza and Lemna gibba,
affect each other’s growth. They set up three containers: one with only Lemna
polyrrhiza, one with only Lemna gibba, and one with both species together. The
graph shows the results of all three experimental trials.
600
L. polyrrhiza alone
L. gibba alone
Dry mass (mg)

400 L. polyrrhiza and

L. gibba together

200

0
0 2 4 6
Weeks’ growth

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Pre-AP Biology Assessments for Learning

4. Which of the following claims is most consistent with the results of the
experiment?
(A) The niches of the two organisms do not overlap; therefore, even when grown
together, they are both able to continue to grow at their maximum growth rate.
(B) There is interspecific competition between the two species; therefore, the
growth of the L. polyrrhiza population is stimulated.
(C) The niches of both organisms likely overlap; therefore, when they are grown
together, interspecific competition reduces the growth of both populations.
(D) L. polyrrhiza has a wider niche than L. gibba; therefore, L. polyrrhiza
experiences a greater population growth even when the species are grown
together.

Assessment Focus

Question 4 assesses students’ ability to use quantitative reasoning as they analyze data
from a graph. In order to select the appropriate claim based on the data, they must
apply their understanding of interspecific versus intraspecific competition and niche.
Correct Answer: C
Learning Objectives:
ECO 2.2(c) Explain how competition for resources shapes populations.
ECO 2.3(b) Analyze data about species distributions to make predictions about the
availability of resources.
Area of Focus: Strategic Use of Mathematics

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Pre-AP Biology Course Designation

Schools can earn an official Pre-AP Biology course designation by meeting the
requirements summarized below. Pre-AP Course Audit Administrators and teachers
will complete a Pre-AP Course Audit process to attest to these requirements. All schools
offering courses that have received a Pre-AP Course Designation will be listed in the
Pre-AP Course Ledger, in a process similar to that used for listing authorized AP courses.
PROGRAM REQUIREMENTS
ƒ The school ensures that Pre-AP frameworks and assessments serve as the
foundation for all sections of the course at the school. This means that the school
must not establish any barriers (e.g., test scores, grades in prior coursework,
teacher or counselor recommendation) to student access and participation in
Pre-AP Biology coursework.
ƒ Teachers have read the most recent Pre-AP Biology Course Guide.
ƒ Teachers administer each performance task and at least one of two learning
checkpoints per unit.
ƒ Teachers and at least one administrator per site complete a Pre-AP Summer
Institute or the Online Foundational Module Series. Teachers complete at least one
Online Performance Task Scoring Module.
ƒ Teachers align instruction to the Pre-AP Biology Course Framework and ensure
their course meets the curricular requirements summarized below.
ƒ The school ensures that the resource requirements summarized below are met.
CURRICULAR REQUIREMENTS
ƒ The course provides opportunities for students to develop understanding of
the Pre-AP Biology key concepts and skills articulated in the course framework
through the four units of study.
ƒ The course provides opportunities for students to engage in the Pre-AP shared
instructional principles.
u close observation and analysis
u evidence-based writing
u higher-order questioning
u academic conversation

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Pre-AP Biology Course Designation

ƒ The course provides opportunities for students to engage in the three Pre-AP
science areas of focus. The areas of focus are:
u emphasis on analytical reading and writing
u strategic use of mathematics
u attention to modeling
ƒ The instructional plan for the course includes opportunities for students to
continue to practice and develop disciplinary skills.
ƒ The instructional plan reflects time and instructional methods for engaging
students in reflection and feedback based on their progress.
ƒ The instructional plan reflects making responsive adjustments to instruction based
on student performance.
RESOURCE REQUIREMENTS
ƒ The school ensures that participating teachers and students are provided computer
and internet access for completion of course and assessment requirements.
ƒ Teachers should have consistent access to a video projector for sharing web-based
instructional content and short web videos.
ƒ The school ensures teachers have access to laboratory equipment and consumable
resources so that students can engage in the Pre-AP Biology inquiry-based model
lessons.

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 About the Course

Accessing the Digital Materials

Pre-AP Classroom is the online application through which teachers and students can
access Pre-AP instructional resources and assessments. The digital platform is similar
to AP Classroom, the online system used for AP courses.

Pre-AP coordinators receive access to Pre-AP Classroom via an access code delivered
after orders are processed. Teachers receive access after the Pre-AP Course Audit
process has been completed.

Once teachers have created course sections, student can enroll in them via access
code. When both teachers and students have access, teachers can share instructional
resources with students, assign and score assessments, and complete online learning
modules; students can view resources shared by the teacher, take assessments, and
receive feedback reports to understand progress and growth.

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 Unit 1

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 Unit 1
Ecological
Systems

Overview
SUGGESTED TIMING: APPROXIMATELY 5 WEEKS

In this unit, students deepen and expand prior knowledge, gained in a middle school
life science course, of how the cycling of matter and flow of energy regulate ecosystems.
Students also apply proportional reasoning skills to examine data, especially bivariate
data, in order to analyze and make scientific claims about patterns, relationships, and
changes in the structure and distribution of ecological populations and communities.
This unit provides students an opportunity to build on and deepen their understanding
of the living and nonliving components that regulate the structure and function of
ecological systems. Students should begin to gain an appreciation for the intricate
and often fragile interdependent relationships that ecological communities rely on.
Students also explore how communities change over time, both through naturally
occurring processes and through human activities.

ENDURING UNDERSTANDINGS
This unit focuses on the following enduring understandings:

Biological systems depend on the cycling of matter within and between Earth’s
systems.
Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

KEY CONCEPTS
This unit addresses the following key concepts:

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 Overview

UNIT 1 ƒ ECO 1: Cycling of Matter in the Biosphere

ƒ ECO 2: Population Dynamics
ƒ ECO 3: Defining Ecological Communities
ƒ ECO 4: Ecological Community Dynamics
ƒ ECO 5: Changes in Ecological Communities

UNIT RESOURCES
The tables below outline the resources provided by Pre-AP for this unit.

Lessons for Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

1.1: Launch Less than Emphasis on

Lesson – 45 minutes Analytical
Important Reading and
Elements in Writing,
Organisms Strategic Use of
Mathematics

1.2: Modeling ECO 1.1(a), ECO 1.1.1a, ~90 minutes Attention to

the Water and ECO 1.1(b), ECO 1.1.1b, Modeling
Carbon Cycles ECO 1.2(a), ECO 1.1.1c,
ECO 1.2(b) ECO 1.1.1d,
ECO 1.2.1a

1.3: Analyzing ECO 1.2(c), ECO 1.2.1b, Less than Strategic Use of
Nitrogen ECO 1.2(d) ECO 1.2.1c 45 minutes Mathematics
Fertilizer Use on
U.S. Corn Crops

1.4: Exploring ECO 1.2(c), ECO 1.2.1b, ~90 minutes Emphasis on

and Modeling ECO 1.2(d) ECO 1.2.1c Analytical
the Nitrogen Reading and
Cycle Writing,
Attention to
Modeling
All learning objectives and essential knowledge statements for
this key concept are addressed with the provided materials.

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 Overview

Practice Performance Task for Unit 1 (~45 minutes) UNIT 1

This practice performance task draws on learning objectives and essential knowledge
statements addressed throughout Key Concept ECO 1: Cycling of Matter in the
Biosphere.

Lessons for Key Concept ECO 2: Population Dynamics

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

1.5: Launch ECO 2.3(a), ECO 2.3.1a, ~45–60 Attention to

Lesson – ECO 2.3(c) ECO 2.3.1b, minutes Modeling
Modeling ECO 2.3.1c
Yellowstone’s
Food Web

1.6: Population ECO 2.1(b) ECO 2.1.1a, ~135 Strategic Use of

Field Studies ECO 2.1.1b, minutes Mathematics
Simulations ECO 2.1.1c,
Lab – Quadrat ECO 2.1.1d
and Mark−
Recapture
Sampling
The following Key Concept ECO 2 learning objectives and
essential knowledge statements are not addressed in Pre-AP
lessons. Address these in teacher-developed materials.

ƒ Learning Objectives: ECO 2.1(a), ECO 2.1(c), ECO 2.2(a),

ECO 2.2(b), ECO 2.2(c), ECO 2.3(b)

ƒ Essential Knowledge Statements: ECO 2.2.1a, ECO 2.2.1b,

ECO 2.2.1c, ECO 2.2.1d, ECO 2.2.2a, ECO 2.2.2b

Learning Checkpoint 1: Key Concepts ECO 1 and ECO 2 (~45 minutes)

This learning checkpoint assesses learning objectives and essential knowledge

statements from Key Concepts ECO 1 and ECO 2. For sample items and learning
checkpoint details, visit Pre-AP Classroom.

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 Overview

UNIT 1 Lessons for Key Concept ECO 3: Defining Ecological Communities

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

1.7: Launch ECO 3.2(a) ECO 3.2.1a, Less than Emphasis on

Lesson – ECO 3.2.1b 45 minutes Analytical
Comparing Reading and
Biomes Using Writing
HHMI’s
BiomeViewer
The following Key Concept ECO 3 learning objectives and
essential knowledge statements are not addressed in Pre-AP
lessons. Address these in teacher-developed materials.

ƒ Learning Objectives: ECO 3.1(a), ECO 3.1(b), ECO 3.2(b)

ƒ Essential Knowledge Statements: ECO 3.1.1a, ECO 3.1.1b,

ECO 3.1.1c, ECO 3.2.2a, ECO 3.2.2b, ECO 3.2.2c

Lessons for Key Concept ECO 4: Ecological Community Dynamics

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

1.8: Launch ECO 4.2(a), ECO 4.2.1a Less than Strategic Use of
Lesson – ECO 4.2(b) 45 minutes Mathematics
Examining
Coral Bleaching
Effects

1.9: Modeling ECO 4.1(c) ECO 4.1.1a, ~90 minutes Attention to

the Importance ECO 4.1.1b Modeling,
of Keystone Emphasis on
Species Analytical
Reading and
Writing

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 Overview

The following Key Concept ECO 4 learning objectives and UNIT 1

essential knowledge statements are not addressed in Pre-AP

lessons. Address these in teacher-developed materials.

ƒ Learning Objectives: ECO 4.1(a), ECO 4.1(b)

ƒ Essential Knowledge Statements: ECO 4.1.1c, ECO 4.1.1d,

ECO 4.2.1b, ECO 4.1.1c

Lessons for Key Concept ECO 5: Changes In Ecological Communities

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

1.10: Launch ECO 5.2(a), ECO 5.2.1a, Less than Emphasis on

Lesson – ECO 5.2(b) ECO 5.2.1b 60 minutes Analytical
Invasive Reading and
Species—Brown Writing,
Tree Snakes in Strategic Use of
Guam Mathematics

1.11: Predicting ECO 5.2(a), ECO 5.2.1a, ~60 minutes Emphasis on

Changes in ECO 5.2(b) ECO 5.2.1b Analytical
Arctic Ecological Reading and
Communities Writing,
Strategic Use of
Mathematics

1.12: ECO 5.1(a), ECO 5.1.1d ~60 minutes Emphasis on

Understanding ECO 5.1(c) Analytical
Beavers as Reading and
Ecosystem Writing
Engineers
The following Key Concept ECO 5 learning objectives and
essential knowledge statements are not addressed in Pre-AP
lessons. Address these in teacher-developed materials.

ƒ Learning Objectives: ECO 5.1(b), ECO 5.2(c)

ƒ Essential Knowledge Statements: ECO 5.1.1a, ECO 5.1.1b,

ECO 5.1.1c

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 Overview

UNIT 1 Learning Checkpoint 2: Key Concepts ECO 3–ECO 5 (~45 minutes)

This learning checkpoint assesses learning objectives and essential knowledge

statements from Key Concepts ECO 3 through ECO 5. For sample items and learning
checkpoint details, visit Pre-AP Classroom.

Performance Task for Unit 1 (~45 minutes)

This performance task assesses learning objectives and essential knowledge statements
from the entire unit.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

LESSON 1.1 UNIT 1

Launch Lesson – Important Elements

in Organisms

OVERVIEW

LESSON DESCRIPTION AREAS OF FOCUS

Students make predictions about the six most ƒ Emphasis on Analytical
common elements in the human body. They Reading and Writing
then provide some scientific reasoning for their ƒ Strategic Use of
predictions. Mathematics

CONTENT FOCUS SUGGESTED TIMING

This lesson focuses on the four classes of Less than 45 minutes
macromolecules and the common elements that
make up those compounds, which students have had
HANDOUT
experience with in middle school life science. Although
ƒ 1.1: Important
most students will not have learned the chemical
Elements in Organisms
structure of these macromolecules, they should have
a solid understanding of the importance of the most
common elements in living systems: oxygen, carbon,
hydrogen, nitrogen, calcium, and phosphorus—the elements that make up the largest
percentage of an organism’s body weight. This lesson also primes student thinking in
preparation for modeling biogeochemical cycles later in this unit.
COURSE FRAMEWORK CONNECTIONS

This first launch lesson connects to prior knowledge students gained in middle school
life science about the importance of oxygen, carbon, hydrogen, nitrogen, calcium, and
phosphorus in the development of macromolecules.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.1: Launch Lesson – Important Elements in Organisms

UNIT 1 PREDICTING OUR MOST COMMON ELEMENTS

Before introducing lessons that demonstrate biogeochemical cycles such as the water,
carbon, and nitrogen cycles, students should be motivated to explore why the cycling of
matter is important for organisms. One way to spark inquiry is to have students make
predictions about the most common elements found in their own bodies. This is also a
great way to elicit prior knowledge about the importance of water, energy production
(cellular respiration), and the stucture and function of human body systems. Students
have likely already learned about these in middle school life science.

ƒ To begin this lesson, have students look at the Meeting Learners’ Needs
diagram on Handout 1.1: Important Elements in If students are struggling to
Lesson 1.1: Launch Lesson – Important Elements in Organisms
Organisms. Based on their prior knowledge, they think of evidence for
their choices, suggest theyUnit 1: Ecological Systems
will fill in the diagram with their predictions about
think about a few things
the six most commonly occurring elements in the
their body relies on, such
human body. The diagram and correct responses
Important
are shown below. (Do Elements
not reveal thein Organisms
correct answers
as breathing or eating,
to spark some ideas.
HANDOUT
1.1
to students until the end of the lesson.)
What are the most commonly occurring elements in the human body?

100%

Total Human Body Weight

65.0% 18.5% 9.5% 3.2%

1.5% 1.0%

The top circle represents total human body weight. The circles in the bottom row represent the six most
abundant elements in the human body.

Handout 1.1

MAKING PREDICTIONS
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1. Using the list of elements provided, predict what you think are the six most
abundant elements in the human body. Label the diagram to show your
predictions.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.1: Launch Lesson – Important Elements in Organisms

ƒ Next, as directed by the handout, students will provide scientific reasoning for UNIT 1
their predictions. The following prompts may be helpful in getting students started
reasoning like a scientist.
u What type of molecules or compounds do you think your body relies on to
function properly? What about for structural support?
u Recall how the food you eat provides you with energy. What elements do you
think that food is made of?
ƒ Students should work with a partner or in a small group to share their answers to the
first two questions on the handout. Encourage students to make revisions to their
original predictions if a peer’s reasoning is persuasive enough to warrant changes.
ƒ Once students have discussed their answers in pairs or small groups, bring them
back together for a whole-class discussion. Have students share their predictions
about the six most commonly occurring elements in their bodies and note the
reasoning they used to support their predictions. They may also note whether they
made any modifications to their original predictions based on a peer’s predictions
and associated reasoning. During the discussion, generate a class list of predictions
and reasoning for the six most common elements in the human body.
ƒ At the end of the discussion, reveal to the class the correct answers.
The six most abundant elements in the human body, in order from most to least
abundant, are oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

ƒ Finally, ask students to note which of their predictions were incorrect. Invite them
to suggest revisions to their scientific reasoning to better support the correct
answers.

Guiding Student Thinking

Student responses will likely identify respiration (use of O2) and the presence of
water as reasons to include oxygen and hydrogen in the list of the six most prevalent
elements. Students may not immediately think of calcium as one of the six. To prompt
this thinking, ask students what might be the building block for bones in our skeletal
system. At this point it is okay for students to simply state that “all living things are
made up of carbon” without being able to explain why. However, this is a good place
to prompt students to think about how carbon serves as the backbone to the building
blocks of life (macromolecules such as carbohydrates, proteins, lipids, etc.). Students
should have at least been introduced to those molecules in middle school life science.
They likely will not know how nitrogen and phosphorus contribute to their bodies,
but this will be the focus of the next few lessons.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

UNIT 1 LESSON 1.2

Modeling the Water and Carbon Cycles

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Part 1: The Importance of Water and Carbon ƒ Attention to Modeling
Students respond to a prompt and answer
questions to elicit their prior knowledge from
SUGGESTED TIMING
middle school about the importance of water and
~90 minutes
carbon in living systems.

Part 2: Modeling the Water and Carbon Cycles HANDOUTS

Students utilize cycling cards to develop one
ƒ 1.2.A: Modeling the
model that illustrates the movement of water and
Water and Carbon
carbon through the ecosystem. They focus on the
Cycles
beginning and ending forms of water and carbon
ƒ 1.2.B: Water and
for each main process in the cycles.
Carbon Cycling Cards,
Part 3: Evaluating Models with cards cut out
Pairs of students swap models and evaluate the
other pair’s work. Students then participate in MATERIALS
a whole-class discussion about the relationship ƒ materials for creating
between the carbon and water cycles. a model, such as the
following:
CONTENT FOCUS u poster paper and

This lesson elicits students’ prior knowledge about the markers

cycling of water and carbon through the ecosystem. u neon markers for lab

Students focus on tracing oxygen through the tables

ecosystem to build models of these cycles. This lesson u computer (laptop,

also aims to deepen student understanding by focusing tablet, etc.)

on the physical and chemical transformations that
occur throughout these important biogeochemical
cycles. Therefore, students identify the beginning and ending forms of water and
carbon compounds as they move through the various processes in each cycles.

Students should understand why phosphorus is a crucial element in many important

biomolecules (e.g., ATP, DNA), but the understanding of this cycle is covered in
AP Biology. Also, students should be able to model the nitrogen cycle from a general

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.2: Modeling the Water and Carbon Cycles

standpoint of how biotic and abiotic components interact and depend on one another. UNIT 1
However, an understanding of chemical conversions during this cycle is beyond the scope of
this course.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological systems depend on the cycling of matter within and between Earth’s
systems.
ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.

Learning Objectives Essential Knowledge

ECO 1.1(a) Explain how the unique ECO 1.1.1 Water cycles between abiotic
properties and phase changes of water and biotic systems in a process known as
enable and regulate biological reactions the hydrologic cycle.
and/or processes. a. The polar nature of water results in
ECO 1.1(b) Create and/or use a model to properties on which biological systems
explain how biological systems function depend, such as dissolving organic and
in the hydrologic cycle as water is inorganic nutrients.
transferred, transported, and/or stored. b. The hydrologic cycle is driven by
energy from the sun and gravity.
c. The largest reservoir of water in the
global hydrologic cycle is the world’s
oceans.
d. A small portion of the water on Earth
is fresh water, which is required for life
by all terrestrial organisms, including
humans.

ECO 1.2(a) Explain the importance ECO 1.2.1 Elements that are
of the cycling of carbon for biological building blocks of macromolecules
systems. are transported from abiotic to
ECO 1.2(b) Create and/or use models to biotic systems through gaseous and
illustrate how organisms’ capture and use sedimentary cycles.
of energy plays a role in the cycling of a. The carbon cycle is a series of
carbon in ecosystems. molecular transformations that includes
photosynthesis and cellular respiration.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.2: Modeling the Water and Carbon Cycles

UNIT 1 PART 1: THE IMPORTANCE OF WATER AND CARBON

Most middle school life and earth science courses require students to gain a basic
understanding of both the water and carbon cycles. Therefore, certain facets of
modeling these two cycles may be familiar to students. However, this lesson is designed
to deepen and extend student understanding of these cycles by focusing on the physical
and chemical transformations that occur as matter cycles through various ecosystem
components, such as the atmosphere, ocean, and plants and animals.

The first part of this lesson is intended to elicit students’ prior knowledge about the
importance of water and carbon in living systems. See Part 1 of Handout 1.2.A:
Modeling the Water and Carbon Cycles.

ƒ Allow students time to carefully read the first

Meeting Learners’ Needs
paragraph of the handout, about the abundance
Some of the information
of oxygen in the human body. Also have students
in the bar graph will
examine the bar graph, which gives the percentage be familiar to students
of total body weight by element. Then, as a whole from the launch lesson.
class, have students share their prior knowledge For students who could
by responding to the following prompt: What use additional practice
important roles does water play in living systems? extracting information
from a graph, you may
Record students’ responses on the board for the
want to discuss with
class to see.
them the pros and cons
Student responses should address topics such as of these different ways
temperature regulation, photosynthesis, waste of representing the
disposal in living systems, metabolism, and habitat. information shown in
the two lessons. Have
Prompt students to consider these topics as needed.
students compare and
ƒ Next, students explore the importance of carbon as contrast different types
the backbone of life’s major macromolecules. They of data displays (e.g., bar
can work individually or in pairs as they read the graphs, line graphs, pie
charts) and identify why
second paragraph and table on the handout, and
the data displays used were
answer the Check Your Understanding questions.
appropriate. This is an
important “just-in-time”
refresher on the purpose of
different type of graphs.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.2: Modeling the Water and Carbon Cycles

UNIT 1
Guiding Student Thinking

While students may remember that carbon serves as the backbone to carbohydrates
and proteins, which make up many of the foods they eat, they may not specifically
recall the term macromolecule. Introduce this term in connection with the most
common elements and the cycling of matter in ecosystems. Then, when the
biochemistry of macromolecules is addressed in Unit 3: Cellular Systems, students will
already have an understanding of how these elements are acquired by organisms as
they cycle through the ecosystem.

PART 2: MODELING THE WATER AND

Classroom Ideas
CARBON CYCLES
There are many tools/
Now that students have revisited the importance of materials that students
water and carbon in the biosphere, it is time for them to can use to create their
explore how these substances cycle through ecosystems. models. A few include:
Students work with a partner to create a single model u Markers on a large
that includes both the water and carbon cycles. See poster paper
Part 2 of Handout 1.2.A and Handout 1.2.B: Water and u Neon markers on dark
Carbon Cycling Cards. lab tables
u Piktocharts (http://
This part of the lesson has students connect their
piktochart.com)
prior knowledge of the water and carbon cycles with a or SageModeler
new understanding of how elements change chemical (http://concord.org/
composition during these cycles. The focus here is our-work/research-
on the beginning and ending forms of each molecule projects/building-
or compound as it undergoes various processes in models) on a computer
or tablet
each cycle.

ƒ Prior to and during this part of the lesson, support

students in understanding the following aspects of the task:
u Getting started. Students should work with a partner to create the model. Indicate
to students the materials you want them to use. Students should also have a set of
cut-out Water and Carbon Cycling cards, in no particular order.
u Using the cards. To develop the model, students will choose one card at a time.
For each card chosen, students should add and revise their model accordingly.
On the cards, carbon cycle processes are denoted by a diamond icon; water cycle
processes are denoted by a water drop icon.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.2: Modeling the Water and Carbon Cycles

UNIT 1
u Following oxygen. Since oxygen is the most
Meeting Learners’ Needs
common element, the model will follow the
You may choose to
transformations of an oxygen atom. scaffold this part of the
u Thinking creatively. Emphasize to students that lesson further by having
they will be developing and revising a concept/ students do the water
process model that shows both the water and cycle cards first. After
reviewing student models
carbon cycles. The modeling process will require
and providing feedback,
creativity as students decide the best way to
allow them to move on
visually represent their ideas. They will also to the rest of the cards
need to provide appropriate connections and to complete the entire
explanations for those connections. model, including carbon.
ƒ Once student pairs have completed their
model, they have the opportunity to test it out.
Students should use the model, along with the cycling cards, to complete the
Transformations and Processes table on the handout.
ƒ As students work on the table, circulate around the room and provide support as
needed. For your reference, the completed table is provided on the next page, with
student responses in blue.

Instructional Rationale

Commonly, the concept of biogeochemical cycling, like carbon, is taught by simply

having students fill in vocabulary words on a model of the cycle that is mostly
developed for them. This type of memorization activity does not help students fully
understand all the processes of the cycle and how they are connected. Having students
construct, critique, and revise their own models allows them to develop a much
deeper understanding of these concepts.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere
Lesson 1.2: Modeling the Water and Carbon Cycles Lesson 1.2: Modeling the Water and Carbon Cycles
Unit 1: Ecological Systems

UNIT 1
HANDOUT TRANSFORMATIONS AND PROCESSES IN THE WATER
1.2.A
AND CARBON CYCLES

Cycles Beginning Form(s) Process Ending Form(s)

Water Liquid Transpiration Vapor (gas)

Water Liquid Evaporation Vapor (gas)

Water Liquid (rain) or Surface runoff Liquid with nutrients

solid (ice) (N + P)

Water Liquid (rain) or Infiltration Liquid

solid (ice)

Water Vapor Condensation Liquid (water drops)

or solid (ice)

Water + Carbon Liquid (rain) or solid Precipitation H2O liquid (rain) +

(ice) + CO2 carbonic acid (H2CO3)

Carbon + Water C6H12O6 + O2 Respiration CO2 + H2O

Carbon + Water CO2 + H2O Photosynthesis C6H12O6 + O2

Carbon Organic matter Deposition Fossils, fossil fuels

Carbon C6H12O6 Assimilation Macromolecules

Carbon CaCO3 Sedimentation Limestone

Carbon Fossil fuels + organic Combustion CO2

matter

Handout 1.2.A

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.2: Modeling the Water and Carbon Cycles

UNIT 1 PART 3: EVALUATING MODELS

The final part of the lesson engages students in assessing and reflecting on their
understanding of these two important cycles. Students evaluate each other’s models
using the Transformations and Processes table they completed in the handout, and
engage in peer-to-peer critique in order to review and revise their models.

ƒ Have each student pair exchange models with another pair and review the other
pair’s model.
ƒ Students should use their Transformations and Processes table to guide feedback
and suggested revisions to the other pair’s model.
ƒ The pairs should then work together to share feedback, examine both models, and
make final revisions to their models and tables.

Instructional Rationale

As with all modeling lessons, the key to deeper understanding for students is in the
process of evaluating other students’ models and in revising their own models based
on those. This process also makes student thinking visible in order to provide more
actionable feedback as they make revisions.

ƒ Finally, bring everyone together for a whole-class discussion. Have students share
their solutions to the table and discuss how their models changed over the design
process. Some guiding prompts for class discussion could be:
u How are the water and carbon cycles connected to one another?
u Describe how organisms directly acquire oxygen, hydrogen, and carbon.
u How does the cycling of water and carbon support an organism’s ability to make
macromolecules?
u In what ways do humans alter the carbon cycle? What about the water cycle?

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

LESSON 1.3 UNIT 1

Analyzing Nitrogen Fertilizer Use

on U.S. Corn Crops

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Students examine a graph from the USDA (United ƒ Strategic Use of
States Department of Agriculture) showing total Mathematics
macronutrient inputs and nitrogen inputs in
comparison to corn yields.
SUGGESTED TIMING
Less than 45 minutes
CONTENT FOCUS
Nitrogen is a limiting factor in many ecosystems due to
HANDOUT
the major role it plays in supporting plant growth. This
ƒ 1.3: Analyzing Nitrogen
lesson highlights how nutrients such as nitrogen help
Fertilizer Use on United
regulate biological systems, and also starts to promote
States Corn Crops
an understanding of how nitrogen can cycle between
living systems. This is a necessary understanding in
MATERIALS
future activities involving the nitrogen cycle.
ƒ calculators (optional)

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops

UNIT 1 COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological systems depend on the cycling of matter within and between Earth’s
systems.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.

Learning Objectives Essential Knowledge

ECO 1.2(c) Explain the importance of ECO 1.2.1 Elements that are
the cycling of nutrients for biological building blocks of macromolecules
systems. are transported from abiotic to
ECO 1.2(d) Create and/or use models to biotic systems through gaseous and
describe the cycling of nitrogen between sedimentary cycles.
biotic and abiotic systems. b. The nitrogen cycle is a series of
transformations that includes the
conversion of nitrogen gas (the largest
reservoir of nitrogen on Earth) into
biologically available nitrogen-containing
molecules (e.g., nitrates).
c. Phosphorus is a critical element for
organisms as it helps make up numerous
biomolecules (e.g., ATP, DNA).

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops

Through the previous lesson on modeling water and carbon cycles, students should UNIT 1
have been able to see how the key elements oxygen, carbon, and hydrogen cycle
through the ecosystem. In this lesson, students focus on the fourth most common
element in living systems, nitrogen. This data analysis is intended to spark student
curiosity and generate questions about the role of nitrogen and how organisms acquire
Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops

Unit 1: Ecological Systems

this element.

Analyzing Nitrogen Fertilizer Use on HANDOUT

EXPLORING
United States THECorn ROLE OF NITROGEN
Crops
1.3

ƒ Remind
Nitrogenstudents that,in agriculture,
is a critical input as they enabling
saw infarmersprior to
Meeting Learners’ Needs
activities, nitrogen is the fourth most vital
produce high crop yields profitably. Elements that are abundant
to
plant growth, such as nitrogen, are referred to as macronutrients. Some students may
element
Althoughinnitrogen
the human bodyin Earth’s
is very common and is necessary
atmosphere, it is for
need additional support
not in a form that plants can use. Many of our staple crops require
making key macromolecules, such as DNA and
large amounts of nitrogen-based fertilizers in order to produce unpacking the information
proteins. As
profitable with
yields. water and
Unfortunately, excesscarbon,
nitrogen from students
farms can in this graph since it
enter water resources or the atmosphere, causing environmental
needproblems.
to understand
Improved nitrogen how nitrogen
management cycleshasthrough
on cropland been
measures three different
ecosystems and how organisms acquire this key
a long-standing goal of USDA conservation policy. variables and includes a
Corn is the most widely planted crop in the United States and the double y-axis. Have them
nutrient.
largest user of nitrogen in terms of application rates per acre, total
first focus on just one
acres treated, and total applications. Corn typically requires a
ƒ Display the graph from Handout 1.3: Analyzing
great deal of nitrogen for maximum growth (yield). Because of the variable, such as nitrogen.
Nitrogen impacts
negative Fertilizer
of excessUse ononUnited
nitrogen States
the environment, Corn
farmers Then help them connect
have been working to develop innovative farming strategies for
Crops (shown
keeping corn yieldbelow)
high whileto the whole
reducing the amountclass.
of nitrogen what is being measured
and other nutrients used in fertilizer. on each axis by asking
United States Corn Yield and Macronutrient Input Levels questions such as:
300
150
u How many pounds of
Corn yield (bushels/acre)
Nutrients (pounds/acre)

250 Total nutrients

130

200
nitrogen per acre were
110
Corn yield
recorded in 2000?
150 90

100
Nitrogen
u How high was the
70

corn yield in bushels

50 50
1964 1970 1976 1982 1988 1994 2000 2006 per acre in 2000?
Years

Text and graph adapted from “Nitrogen Management on U.S. Corn Acres, 2001-10.” © 2012 by USDA,
Handout
Economic 1.3
Research Service, and USDA, National Agricultural Statistics Service.

ƒ Now engage students in a whole-class discussion to help orient them to the graph
and promote close observation of the data. Prompts to encourage this include:
Student Resource 11 Pre-AP Biology
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u What two distinct variables are shown on the y-axis?
u What can a given data point on this plot stand for or represent? (List all options.)
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included in the total nutrient measurement. Why do you think this is the case?

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops

UNIT 1 ƒ Next, have students work individually or in small groups on Handout 1.3. They
should begin by examining the passage about nitrogen fertilizer use from the
USDA, then move on to answering the Check Your Understanding questions.
These questions require close observation and analysis of the data in the passage
and the graph. For example:
u The questions scaffold development of effective routines for data analysis, such as
looking at major and minor trends found within the graph.
u The last question engages students in sentence expansion to help them craft
coherent evidence-based written claims. They should develop three unique
sentences that begin with the same independent clause, “Nitrogen helps increase
corn yield … ,” using each of the following conjunctions: because, but, so.
WHOLE-CLASS DISCUSSION
ƒ Once students have completed the handout, lead a whole-class discussion in which
students share their answers to the Check Your Understanding questions. Sample
responses are shown on the next page.
ƒ Some additional prompts to promote critical thinking during the class discussion
could include:
u Another macronutrient found in fertilizer is phosphorus. Why would phosphorus
be included in fertilizers?
u Why is it important for farmers to continue to improve farming practices so that
they can limit fertilizer use?

Instructional Rationale

Often students engage with the nitrogen cycle with very little real-world
understanding about its importance. These whole-class discussion questions provide
some context as to why nitrogen is important prior to the next lesson, where students
model the nitrogen cycle.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere
Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops
Lesson 1.3: Analyzing Nitrogen Fertilizer Use on U.S. Corn Crops
Unit 1: Ecological Systems

UNIT 1
HANDOUT CHECK YOUR UNDERSTANDING
1.3

1. Calculate the average rate of change in corn yield from 1964 to 2008. (Round to
the nearest whole number.)

change in corn yield

change in years

90 bushels per acre 2 bushels per acre

=
44 years 1 year
2. Describe the overall trend in corn yield from 1988 to 2008. How does the trend in
corn yield during that time compare to trends for total nutrients and nitrogen?
Sample response: The overall trend is increasing for each of the variables measured.
(Note: Students may want to draw a line of fit to help them analyze the overall
trend.)

3. At the highest measurement for total nutrients, what percentage of the total
nutrients is nitrogen?
Sample response: The nutrient input was 300 lbs/acre and nitrogen accounted
for 150 lbs of that—or roughly half. (Note: Students should be able to estimate
this answer by quickly examining the year 1983.)

4. Complete the sentences below using evidence from the sources.

Nitrogen helps increase corn yield because it is a key nutrient for plant growth

Nitrogen helps increase corn yield, but too much nitrogen-based fertilizer can

harm the environment .

Nitrogen helps increase corn yield, so farmers will continue to look for better

farming practices that reduce nitrogen-based fertilizer use but keep corn yield

high .

Handout 1.3

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

UNIT 1 LESSON 1.4

Exploring and Modeling the Nitrogen Cycle

OVERVIEW

LESSON DESCRIPTION AREAS OF FOCUS

Part 1: Exploring the Nitrogen Cycle ƒ Emphasis on Analytical
Students read an excerpt from a Nature Education Reading and Writing
article and develop modeling cards from their ƒ Attention to Modeling
reading notes.

Part 2: Modeling the Nitrogen Cycle SUGGESTED TIMING

Student groups use the modeling cards developed ~90 minutes
by their classmates to develop a nitrogen cycle
model. They then form larger groups to evaluate HANDOUTS
their models.
ƒ 1.4.A: Exploring the
Nitrogen Cycle
CONTENT FOCUS ƒ 1.4.B: Nitrogen Card
In this lesson, students apply analytical reading and Template, with multiple
writing skills to a text about the nitrogen cycle and cards cut out for each
then use their notes to develop a model of the cycle. group
This is likely students’ first introduction to the nitrogen ƒ 1.4.C: Modeling the
cycle, so a deep understanding of chemical conversions Nitrogen Cycle, at least
during this cycle, as well as an understanding of the one per group
cycling of sulfur and phosphorus in the ecosystem
are beyond the scope of this course and will be taught
in AP Biology. However, students should develop a
basic understanding of the transformations that occur
during the nitrogen cycle (beginning and ending
forms of nitrogen) and the processes that cause those
transformations.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.4: Exploring and Modeling the Nitrogen Cycle

COURSE FRAMEWORK CONNECTIONS UNIT 1

Enduring Understandings

ƒ Biological systems depend on the cycling of matter within and between Earth’s
systems.

Learning Objectives Essential Knowledge

ECO 1.2(c) Explain the importance of ECO 1.2.1 Elements that are
the cycling of nitrogen for biological building blocks of macromolecules
systems. are transported from abiotic to
ECO 1.2(d) Create and/or use models to biotic systems through gaseous and
describe the cycling of nitrogen between sedimentary cycles.
biotic and abiotic systems. b. The nitrogen cycle is a series of
transformations that includes the
conversion of nitrogen gas (the largest
reservoir of nitrogen on Earth) into
biologically available nitrogen-containing
molecules (e.g., nitrates).
c. Phosphorus is a critical element for
organisms as it helps make up numerous
biomolecules (e.g., ATP, DNA).

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.4: Exploring and Modeling the Nitrogen Cycle

UNIT 1 PART 1: EXPLORING THE NITROGEN CYCLE

In the first part of this lesson, students read an excerpt
Meeting Learners’ Needs
from a Nature Education article and develop modeling
It is important for students
cards from their reading notes. The reading discusses
to be able to extract
the main ways that nitrogen cycles through ecosystems information from these
and how organisms acquire it. types of scientific texts.
However, there are lots
ƒ In the prior data analysis activity with corn,
of scaffolding options
students were able to see that plants rely
so that all students can
on nitrogen to grow. Remind students that nitrogen engage in this task. Some
is the fourth most abundant element in living examples include:
organisms and that it is necessary for making u After students read
key macromolecules, such as DNA and proteins. and annotate the text,
Therefore, organisms must have a way to acquire you can have them
this key nutrient. work with a partner
to go over any words
ƒ Next, have students work independently through
they didn’t recognize
the reading to identify key processes of the and summarize their
nitrogen cycle. Guide students to use metacognitive key ideas together.
annotation strategies as they are reading, such u You can read the

as circling words they don’t know, underlining text aloud and have
key ideas, and summarizing in their own words students make a list
in the margin to capture relevant information. of words that are
Encourage students to also look for the beginning unfamiliar, then work
in groups to define
and ending forms of nitrogen during each process.
and summarize key
See Handout 1.4.A: Exploring the Nitrogen Cycle.
ideas.
You may want to mention to students that they
will be asked to use their notes from the reading to
make modeling cards like those provided in the water and carbon cycling activity.
ƒ After students have read independently, lead a whole-class debrief to ensure they
were able to extract the key information from the text. You may want to include
prompts such as:
u Did anyone circle a word that was unfamiliar to them?
u Describe an example that you underlined that represents nitrogen changing forms
after a natural process.
u Describe an example that you underlined that represents nitrogen changing forms
after a human-induced process.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.4: Exploring and Modeling the Nitrogen Cycle

ƒ Next, have students work in groups of three or four to develop cycling cards for the UNIT 1
nitrogen cycle. See Handout 1.4.B: Nitrogen Card Template. These cards should
mirror the cards used to develop their water and carbon cycles models.
ƒ There is no set number of cards that students should produce. However, highlight for
students that there should be enough cards to adequately model the nitrogen cycle.

PART 2: MODELING THE NITROGEN CYCLE

Now that students have read the excerpt and developed cards based on their notes, they
can exchange cards and use the other group’s cards to model the nitrogen cycle. They
will then form larger groups to evaluate their models.

ƒ First, have each group exchange their set of cycling cards with another group.
Then, students should create a model using the other group’s cards and a copy of
the provided scene. See Handout 1.4.C: Modeling the Nitrogen Cycle.
ƒ Once groups have constructed a model, ask them to highlight any key processes of
the nitrogen cycle that they think were missing from the other group’s cards.
ƒ The groups should then engage in peer-to-peer discussion to collaboratively
examine the two models they created. Write the following tasks on the board for
students to address during their discussions:
1. Compare and contrast the two models. How are they different? How are they the
same?
2. Discuss possible revisions to each model based on your comparisons. Be sure to
cite evidence from the article to support your ideas.
3. Make revisions to the models based on the group’s discussion.
ƒ Finally, lead a whole-class discussion by having students share the transformations
and processes reflected in their models of the nitrogen cycle. Throughout the
discussion, capture student responses in a table (projected or on the board) for
students to see. By the end, ensure that the class identifies all the transformations
and processes in the table provided on the next page.

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 Key Concept ECO 1: Cycling of Matter in the Biosphere

Lesson 1.4: Exploring and Modeling the Nitrogen Cycle

UNIT 1 NITROGEN CYCLE TRANSFORMATIONS AND

PROCESSES

Location Beginning Form(s) Process Ending Form(s)

Atmosphere N2 Nitrogen fixation NO3– (nitrate)

by lightning

Soil Organic matter Nitrogen fixation NO3– (nitrate) and/or

by decomposers ammonium (NH+4)

Soil NO3– (nitrate) Bacterial N2

denitrification

Plants N2 Nitrogen fixation by NO3– (nitrate) or

symbiotic bacteria NH4+ (ammonium)

Plants NO3– (nitrate) or Assimilation Plant proteins,

NH4+ (ammonium) nucleic acids

Animals Plant proteins, Assimilation Animal proteins,

nucleic acids nucleic acids

Agriculture Fertilizers Assimilation Plant (crop) proteins,

nucleic acids

Oceans Fertilizers Assimilation/algal Algae proteins,

bloom nucleic acids

Industry N2 Industrial nitrogen NH4+ (ammonium)

fixation

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 Practice Performance Task: Termites, Guardians of the Soil

PRACTICE PERFORMANCE TASK UNIT 1

Termites, Guardians of the Soil

AREA OF FOCUS
ƒ Emphasis on Analytical
OVERVIEW
Reading and Writing

DESCRIPTION
SUGGESTED TIMING
Students read an excerpt from a New York Times
article about the role of termites as soil engineers. ~45 minutes
Students must then use evidence from the article
and from previous lessons to support claims HANDOUT
about the cycling of matter. ƒ Practice Performance
Task: Termites,
CONTENT FOCUS Guardians of the Soil
This practice performance task allows students
an opportunity to transfer the knowledge they’ve MATERIALS
developed in recent activities to a novel context, ƒ copies of scoring
termites. This final task for Key Concept ECO 1: guidelines for student
Cycling of Matter in the Biosphere is also a great use (optional)
transition to the next key concept of population
dynamics.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological systems depend on the cycling of matter within and between Earth’s
systems.
ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.

This practice performance task draws on learning objectives and essential knowledge
statements addressed throughout Key Concept ECO 1: Cycling of Matter in the
Biosphere.

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 Practice Performance Task: Termites, Guardians of the Soil

UNIT 1 SUPPORTING STUDENTS

BEFORE THE TASK
ƒ Question 1. This question uses sentence-crafting to help students thoughtfully
develop some initial claims about termites based on the text. Students practiced a
similar technique in the data analysis lesson on nitrogen fertilizer use. This time,
only the first word of each sentence is provided: although, when, and if. You may
want to alert students to this difference prior to starting the performance task.
ƒ Question 2. Prior to starting the task, you may want to remind students that while
they should cite evidence from the text to support their claims, they should also
use their knowledge of the water, carbon, and nitrogen cycles to elaborate on that
evidence with scientific reasoning.
ƒ Question 3. Encourage students to use their prior knowledge from the lessons to
explain how humans affect the various cycles of matter.
DURING THE TASK
Since this is the first practice performance task in this course, the open-ended question
type may initially seem difficult for students. To help build students’ confidence with
this question type, you may want to use one of the following strategies:
ƒ Let them do this as a homework assignment and then do a whole-class evaluation
using the Scoring Guidelines.
ƒ Have students work in teams to answer the questions, and then switch with another
group and use the Scoring Guidelines to provide written feedback.

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 Practice Performance Task: Termites, Guardians of the Soil

SCORING GUIDELINES UNIT 1

There are 9 possible points for this practice performance task.

Question 1

Sample Solutions Points Possible

Responses will vary. Some possible 3 points maximum

answers include: 1 point for each appropriate sentence
Example 1: Scoring note: While it would be ideal if
Although some termites are considered students used the three sentences together
pests, termites help plants get water. to form one idea, it is not necessary at
When termites dig into the soil, they this point. Each sentence could represent
allow more water to move down into the a different idea as this is just an opening
soil and reach the plants’ roots. question to get them into the text.
If termites were not in the ecosystem,
more water would evaporate or run off
instead of going into the soil.
Example 2:
Although termites are very small, they
can be a big help to plants by providing
nutrients.
When bacteria in termites’ guts convert
nitrogen into usable fertilizer, plant
communities benefit.
If termites did not have these bacteria in
their guts, the plant community might not
grow as well.
Targeted Feedback for Student Responses

Since this is just practice, it is okay for students to form three disconnected sentences,
all focusing on unique ideas. However, if they do, provide feedback that it is better
to form connected sentences to support one idea, and challenge them to write two
connected sentences from one of their current ones.

TEACHER NOTES AND REFLECTIONS

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 Practice Performance Task: Termites, Guardians of the Soil

UNIT 1 Question 2

Sample Solutions Points Possible

Evidence from Text Scientific Reasoning 4 points maximum

ƒ Allowing the plants Each piece of evidence 1 point for each piece of
that surround them to should be adequately evidence pulled from text
persist on a fraction paired with a reason as to that aligns to an impact in
of the annual rainfall why this is beneficial to a cycle
otherwise required to a particular cycle. Some 1 point for each
bounce back after a examples include: appropriate reasoning
withering drought Example 1: statement attached to the
ƒ Poking holes, or Evidence: Allow rain to evidence
macropores, as they dig soak deep into the soil
through the ground rather than running off or
ƒ Allow rain to soak deep evaporating
into the soil rather Reasoning: This impacts
than running off or the water cycle in a way
evaporating that is beneficial to plants
ƒ Artfully mix inorganic since more water will be
particles of sand, stone available in the soil for
and clay with organic them to use.
bits of leaf litter Example 2:
ƒ Blending that helps the Evidence: Artfully mix
soil retain nutrients inorganic particles of sand,
and resist erosion stone and clay with organic
ƒ Stickiness of a termite’s bits of leaf litter
feces and other bodily Reasoning: This impacts
excretions lend the carbon and nitrogen
structure and coherence cycle since it speeds up
to the soil, which also deposition and helps the
prevents erosion soil hold more nutrients
ƒ Bacteria in the termite’s such as nitrogen and
gut are avid nitrogen phosphorus.
fixaters, able to extract
the vital element from
the air and convert it
into a usable sort of
fertilizer
Targeted Feedback for Student Responses

If students don’t cite specific evidence from the reading, have them return to the text to
find specific examples.

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 Practice Performance Task: Termites, Guardians of the Soil

UNIT 1
TEACHER NOTES AND REFLECTIONS

Question 3

Sample Solutions Points Possible

ƒ Removing water from storage for 2 points maximum

drinking impacts the water cycle. 1 point for each correct description of a
ƒ Farming practices increase human activity that affects the cycling of
evaporation from soil and runoff matter
impacts the water and nitrogen cycles. 1 point for each appropriate sentence
ƒ Using fossil fuels for energy releases
carbon dioxide and ammonia into
the atmosphere, which impacts the
carbon and nitrogen cycles.
ƒ Using nitrogen-based fertilizers in
farming impacts the nitrogen cycle.
Targeted Feedback for Student Responses

Some students may use more vague language to describe the human activities. If they
do, have them return to their carbon and nitrogen models from the prior lessons to
find more specific language to include.

TEACHER NOTES AND REFLECTIONS

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 Key Concept ECO 2: Population Dynamics

UNIT 1 LESSON 1.5

Launch Lesson – Modeling

AREA OF FOCUS
Yellowstone’s Food Web
ƒ Attention to Modeling

OVERVIEW
SUGGESTED TIMING

LESSON DESCRIPTION ~45–60 minutes

Part 1: Investigating Species in Yellowstone
National Park HANDOUT
Students examine information about species in ƒ 1.5: Species
Yellowstone National Park to develop a table that Information Cards
identifies, describes, and provides examples of
ecological roles of organisms in food webs. MATERIALS

Part 2: Modeling the Food Web in Yellowstone ƒ internet access and a

National Park projector, computers,
Students use the information they generated in or other technology for
their table and on the species cards to develop a students to view online
model of the Yellowstone food web. images
ƒ scissors
ƒ rulers (optional, for
CONTENT FOCUS
making tables)
To spark student curiosity about population dynamics,
ƒ one of the following
this lesson invites students to examine and model
sets of items for model
the food web of one of our most diverse and complex
development:
national parks—Yellowstone National Park in
u large poster or
Wyoming. The lesson is designed to elicit students’
butcher block paper
prior knowledge of terrestrial food webs and species’
and markers
ecological roles (e.g., primary consumer). As students
u neon dry-erase
extract information from species information cards to
markers for writing
determine key species interactions, they will deepen
on lab tables
and extend their understanding of how energy flows
u mini-whiteboard and
through ecosystems. Understanding these foundational
dry-erase markers
concepts prepares students for a deeper exploration of
population and community dynamics in subsequent
lessons.

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 Key Concept ECO 2: Population Dynamics

Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web

COURSE FRAMEWORK CONNECTIONS UNIT 1

Enduring Understandings

ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.

Learning Objectives Essential Knowledge

ECO 2.3(a) Create and/or use models to ECO 2.3.1 Energy availability helps
explain the transfer of energy through shape ecological communities.
the food web of a community. a. Typically, only 10 percent of the total
ECO 2.3(c) Make predictions about energy in a given trophic level is available
the energy distribution in an ecosystem to organisms in the next higher trophic
based on the energy available to the level.
organisms in any trophic level. b. The metabolic activity required to
utilize the energy available in any given
trophic level results in a loss of thermal
energy to the environment, as heat.
c. The energy available to organisms
decreases from lower-order trophic levels
(primary producers) to higher-order
trophic levels (tertiary consumers).

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 Key Concept ECO 2: Population Dynamics

Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web

UNIT 1 PART 1: INVESTIGATING SPECIES IN YELLOWSTONE NATIONAL PARK

While the Yellowstone food web is abundant and complex, the model students
develop includes only the following species: aspen trees, wheatgrass, wolves, beavers,
coyotes, pronghorn, elk, and brown bears. In this part of the lesson, students examine
information about these species in preparation for the modeling task.

ƒ Have students spend a few minutes exploring the wildlife and plant image galleries
found at Yellowstone’s Nature webpage: www.nps.gov/yell/learn/nature. (Students
can do this together as a class or on their own.) These images provide a sense of
Yellowstone’s diversity. As students are viewing the images, you could ask them to
estimate how many species of mammals, birds, or plants are found in the park
(67 mammal species, nearly 300 bird species, and more than 1,000 plant species).
ƒ Next, group students into pairs and provide
Meeting Learners’ Needs
them with the handout containing the species
Students will likely have
information cards (Handout 1.5: Species various levels of knowledge
Information Cards). Before having students cut about the terms on the
out the cards, give them an opportunity to closely cards. This is a good
observe and analyze the information provided opportunity for students
on each card. To help students navigate the cards’ to work together to share
complex textual information, ask them to read each knowledge and develop a
collective understanding
card and circle any word that seems to describe
of these terms. Some terms
the species’ ecological role or feeding habits (e.g., will be new to students—
herbivore, apex predator). Also have them draw a for example, carrion.
box around any additional words they can define Encourage students to use
(e.g., carrion). the context provided in
the species information
ƒ Student pairs will now collaborate to develop
cards to help them define
working definitions for the terms they marked
these new terms.
with a circle or box. Ask students to create and
fill in a table like the one shown on the next page.
Make a blank copy of this table (either on the board or large poster paper) so that
all students can see it. Sample student responses are included on the next page for
reference.
ƒ Encourage students to fill in at least seven terms on their table, but note that more
are possible. (By having students draw their own tables, rather than filling in a
provided template, you can help signal that there is no fixed number of terms
students should have.)

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 Key Concept ECO 2: Population Dynamics

Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web

Ecological Role Definition Example(s) UNIT 1

Primary producers Photosynthetic organisms that occupy Wheatgrass, aspen

the base of the food chain/web

Primary Organisms that obtain energy/nutrients Pronghorn, elk,

consumers by consuming primary producers; beaver
herbivores

Herbivores Organisms that feed on primary Pronghorn, elk,

producers (e.g., plants) beaver

Secondary Organisms that obtain energy/nutrients Grizzly bear,

consumers by consuming other consumers, or coyote
by consuming both producers and
consumers; carnivores and omnivores

Omnivores Organisms that feed on both producers Grizzly bear

(e.g., plants) and consumers (e.g.,
animals)

Carnivores Organisms that feed only on other Grey wolf, coyote

consumers (e.g., animals)

Apex predators Organisms that have no known natural Grey wolf

predators

ƒ Once students have had enough time to closely examine the cards and create their
table, invite them to share terms, descriptions, and examples in a whole-class
discussion. Let students know that their tables will contain a variety of different
terms, based on which words they marked.
ƒ While all responses should be shared and discussed, emphasize the terms about
ecological roles: primary producer, primary consumer, herbivore, secondary
consumer, omnivore, carnivore, and apex predator. All students should make sure to
record these seven terms on their table; these will be important for the next part of
the lesson.

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 Key Concept ECO 2: Population Dynamics

Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web

UNIT 1 PART 2: MODELING THE FOOD WEB IN YELLOWSTONE NATIONAL PARK

In this part of the lesson, students use the species cards along with the information in
their table to develop a model of the Yellowstone food web.

ƒ First, have students take a few minutes to cut out the species information cards.
Then, they can begin to position the cards to make a model of Yellowstone’s food
web. Once students feel they are landing on their final model, ask them to label
their model using the terms for ecological roles in their table.

Instructional Rationale

The species information cards are written to challenge students as they engage in
modeling. For example, the coyote card indicates that they eat pronghorn and rodents.
Some students, though, may not recognize that a beaver is a rodent, and therefore will
not include the connection between coyotes and beavers in their model. Or, they may
struggle with prior perceptions of brown (grizzly) bears as apex predators, when in
reality brown bears eat a lot of vegetation and scavenge on the kills of wolves (carrion).
The cards are designed this way to allow productive thinking and peer-to-peer
discussion to take place among the students as they create their models.

ƒ As you monitor each pair’s development and

Classroom Ideas
revision process, look for students placing the
While students could
arrows in the appropriate direction of the energy just write the plant and
flow and labeling ecological roles accurately. A animal names on paper
sample student response is shown on the next page. to sketch the model, it is
better for them to be able
to move the pieces around
as they think through
and revise their model
based on peer and teacher
feedback. Students could
place cards on large poster
paper, mini-whiteboards,
or lab desks, and then use
markers to draw energy
arrows and add labels.

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 Key Concept ECO 2: Population Dynamics

Lesson 1.5: Launch Lesson – Modeling Yellowstone’s Food Web

Apex UNIT 1

predator

Wolf
Carnivores,
omnivores,
secondary
consumers
Brown bear
Coyote

Herbivores,
primary
consumers
Beaver Pronghorn Elk

Primary
producers

Aspen tree Western

wheatgrass

ƒ To wrap up this part of the lesson, have students do a gallery walk to provide
feedback on models developed by other student pairs. Finally, engage them in a
whole-class discussion to build a shared understanding of Yellowstone’s food web.

Guiding Student Thinking

It is important that students think about how energy transfer is represented in

this system. You may have to explicitly prompt student thinking about both of
these concepts with some questions such as, “How does the amount of energy in
this ecosystem depend on how much sunlight western wheatgrass and aspen trees
receive?” Students should know that plants need sunlight to grow and that producers
make up the largest biomass of available energy in most ecosystems.

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 Key Concept ECO 2: Population Dynamics

UNIT 1 LESSON 1.6

AREA OF FOCUS
Population Field Studies ƒ Strategic Use of
Simulations Lab – Quadrat and Mathematics
Mark−Recapture Sampling
SUGGESTED TIMING
OVERVIEW
~135 minutes

LESSON DESCRIPTION
HANDOUT
Part 1: Quadrat Sampling
ƒ 1.6: Population Field
Students watch an HHMI video about the Great
Studies Simulations
Elephant Census to spark thinking about the need
Lab
for population sampling methods. They then
carry out a simulated field study in which they
MATERIALS
apply the quadrat sampling method.
ƒ red kidney beans
Part 2: Mark–Recapture Sampling
ƒ white navy beans
Students are introduced to the mark–recapture
ƒ tape
sampling method. They think critically about
ƒ metersticks
necessary assumptions in this method and
ƒ paper bags
perform a simulated field study using mark and
ƒ straws
recapture. Then, they evaluate this method by
ƒ LCD projector,
analyzing and interpreting data.
electronic whiteboard,
Part 3: Comparing Sampling Methods or other technology to
Students compare the quadrat and mark− show an online video
recapture sampling methods, drawing on their ƒ internet access to the
experiences running the two simulations. They HHMI BioInteractive
also revisit applications of population sampling. video “The Great
Elephant Census”
CONTENT FOCUS (8:23), available at
Prior to performing this lab, students should have a www.hhmi.org/
basic understanding of a population, a community, biointeractive/great-
and an ecosystem, and be able to distinguish between elephant-census
the three. Through the topic of the Great Elephant
Census, students explore various survey methods
and mathematical models for estimating population
density and distribution, community structure, and
how species diversity impacts environmental quality.

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

This allows students to apply and reinforce their proportional reasoning skills as UNIT 1
they analyze and predict population density and size. Biologists require this kind of
information to make informed decisions about wildlife and habitat management; this
understanding provides the lens through which students explore population sampling.

Once students have an understanding of sampling methods, this lab should be

conducted in the field, if possible. Students later connect concepts from this lab lesson
to Unit 2 concepts such as coevolution, the importance of variation and diverse gene
pools, and how changes in the ecosystem can lead to extinction and/or speciation.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ The dependence on the availability of abiotic and biotic resources results in

complex and dynamic interactions between organisms and populations.

Learning Objectives Essential Knowledge

ECO 2.1(b) Collect and/or use data to ECO 2.1.1 Species live in a defined range
predict population size, density, and/or of abiotic and biotic conditions, or niche.
distribution. a. Sunlight serves as the primary energy
input for most ecosystems.
b. Species have a range of tolerance for
abiotic resources and conditions (e.g.,
sunlight, nutrients, pH, temperature).
c. Biotic conditions, such as the
behavior of social groups or intraspecific
competition for mates and food, also
influence population structure.
d. Environmental changes can alter the
availability of abiotic and biotic resources
and conditions (e.g., climate changes,
drought, fire, floods).

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

UNIT 1 PART 1: QUADRAT SAMPLING

Students watch a video about the Great Elephant Census project to spark thinking
about the need for population sampling methods. Students then carry out a simulated
field study in which they apply the quadrat sampling method.
INTRODUCTION TO POPULATION SAMPLING
The video that kicks off this lesson illustrates for students the importance of collecting
data about populations. Over the past few years, biologists have been conducting, for
the first time, a survey of elephant populations across the entire African continent. This
survey is being called the Great Elephant Census. Elephants are rapidly disappearing
from the African landscape, primarily due to habitat loss and poaching for ivory.
Officials have limited budgets, resources, and staff to help protect the elephants.
Knowing how many elephants there actually are and where these populations are
located may help officials make better decisions about where to invest their money,
resources, and workers more efficiently.

ƒ Have students watch “The Great Elephant

Classroom Ideas
Census” from HHMI BioInteractive (https://
If instructional time is
www.biointeractive.org/classroom-resources/ an issue, you can have
great-elephant-census). In the video, students students watch the HHMI
learn about one technique being used to track and BioInteractive video at
estimate the size of Africa’s elephant populations. home and answer the
As students watch, have them answer the following associated questions prior
questions: to starting this lesson.

u Why must scientists use sample counts for

elephants instead of counting them directly?
For large moving populations, like elephants, it is often too difficult to count
them directly.
u What is the purpose of defining a specific quadrat transect for counting the
elephants?
Having specific area parameters allows the scientists to make predictions about
the total population of elephants in a much larger area based on their sample
counts collected.
u Why is it important to get an accurate count of the elephant population?
This information is extremely valuable in guiding management and policy
decisions regarding elephant protection, especially since these animals are at risk
from poaching.

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 Population Field Studies Simulations Lab HANDOUT
1.6

Part 1: Quadrat Sampling

THE QUADRAT SAMPLING METHOD AND DENSITY Key Concept ECO 2: Population Dynamics
Quadrat sampling is Lesson
often used for estimating populations that have limited or no
1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
movement, such as plant populations. This method typically involves constructing a
predetermined four-sided sampling boundary (e.g., rectangle or square). Sometimes
circular plots or other shapes are used in quadrat sampling studies as well. As you
THE
saw QUADRAT SAMPLING
in the video about the GreatMETHOD AND DENSITY
Elephant Census project, a long skinny quadrat was UNIT 1
Prior starting the simulation, students should consider how population sampling
used to transect a large area to provide boundaries for estimating the African elephant
population.
leads to population estimates. This exploration will introduce students to vital concepts
inScientists
population sampling
use the techniques:
average density density
found in all the and average
quadrats density.
to calculate estimates for
a population in a known area. Consider this example: A marine ecologist wants to
ƒ First, have students read the introductory text about quadrat sampling and density
estimate the population size of two echinoderm species (sea stars and sand dollars) in
on the handout.
an artificial reef alongThey should
the coast then that
of Florida examine the quadrat
spans 3,600 diagram
square meters ofThey
(m 2 ). the sea stars and
sandtodollars.
decide See Part
use a quadrat Handout
1 of as
transect, 1.6: Each
shown below. Population Field
side of the Studies
quadrat Simulations Lab.
measures
2
2 m, thereby giving a total surface area of 12 m sampled (6 m × 2 m).

Number of organisms
Density =
Area

SIMULATING
Handout 1.6 THE QUADRAT SAMPLING METHOD
During this activity, you will work with your lab group to simulate the quadrat method
ƒ Next, lead a whole-class discussion to promote
used by the marine ecologist in the example given above. Instead of sea stars and
Meeting sand
Learners’ Needs
student thinking about density. The following
dollars, you will be using red and white beans to simulate two different organisms you
It is likely that students
areguiding
sampling.questions may be helpful: may need some additional
u Ask students to craft a ratio of sand dollars to sea “just-in-time” refreshment
stars for just the first quadrat on the left. of these skills. For practice,
you could ask students
Ratio = 1: 2
to first think about a
u Next, have them write a ratio for each context they are more
echinoderm that represents the density for that familiar with, such as:
Student Resource same quadrat. You may want to27
remind students There are 27 students Pre-AP Biology
© 2021 College Board
and 9 teachers eating
that ratios can be also be expressed as fractions.
in a cafeteria that
1 sand dollar 2 sea stars 1 sea star
; or measures 9 m × 9 m .
4 m2 4 m2 2 m2
u What is the density of
BIO_U1_SR.indd 27 u Finally, have them predict what the population 24/03/20 9:43 PM
people eating in the
of sand dollars would be if they sampled 8 m 2 of
cafeteria?
the reef. What would the population of the sea 36 people/81 m 2
stars be if they sampled 12 m 2 of the reef?
= 4 people/9 m 2
u What is the ratio of
students to teachers?
27 teachers: 9 students
or 3:1 ratio

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

UNIT 1 Students should be able to do these calculations quickly in their head. For the
sand dollars, they should see that 8 m 2 of the reef is two times larger than the
first quadrat, and therefore predict a population of two sand dollars, based on the
original density sampling ratio. For the sea stars, 12 m 2 is three times larger than
the first quadrat; therefore, they should predict a population of six sea stars, based
on the original density sampling ratio.

Instructional Rationale

Biologists rely on mathematics in order to analyze their data. This lesson allows
students to engage in the type of thinking scientists would do to estimate population
sizes. The lesson asks students to think about the sample population as one part of a
whole (or true population). This type of proportional thinking should not be new to
students as they begin developing these type of ideas in third- and fourth-grade
mathematics, but this is a good way to continue to strategically reinforce these
concepts so students become more proficient with them.

ƒ Students should also understand the value of multiple trials. Ask students to think
about why using only one quadrat to draw conclusions about a larger area would be
problematic. Invite students to share and discuss their responses.
ƒ Now that students understand why the marine ecologist would use multiple trials,
ask them to find the average density of the echinoderm populations. You may need
to explain to students that to find the average density, we need to know the density
across all three quadrats.
6 1
Average density of sand dollars = 2
or
12 m 2 m2
6 1
Average density of sea stars = 2
or
12 m 2 m2
ƒ Finally, to reinforce student understanding of how to use density and average
density to make population predictions, ask the following questions:
u What is the predicted sand dollar population in a 30 m2 area of the reef?
15 sand dollars
u What is the predicted sea star population in a 90 m2 area of the reef?
45 sea stars
u What are the predicted sea star and sand dollar populations in the entire reef
(3,600 m 2)?
1,800 for each species

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

SIMULATING THE QUADRAT SAMPLING METHOD UNIT 1

Classroom Ideas
Now that students have been introduced to how
Students could also make
population density, patterns, and distribution are
quadrats out of card stock
studied, they will simulate a quadrat study using two or thick construction
different colors of beans. See Part 1 of Handout 1.6: paper instead of straws.
Population Field Studies Simulations Lab. (It is always To do so, they would
best to have students conduct studies in the field when make a frame (quadrat)
time allows. The simulations in this lab lesson provide by cutting a measured
square or rectangle out of
effective ways for students to engage with the sampling
the center of the card.
methods and the type of ratio calculations used to
estimate population density, prior to conducting field
studies. See the extension section at the end of this lab
Meeting Learners’ Needs
for ideas about follow-up laboratory work in sampling.)
If students are having
ƒ In the simulation, students will perform the trouble predicting
following general steps (described in greater detail population density using
on the student handout): the area of all three
quadrats, first have them
u Define the sampling plot. Students mark a do this using just one
boundary area for sampling on their lab desks quadrat. Guide students
or on the floor if there is not enough desk space. students in setting up
Next, they should spread ample handfuls of both the following example:
color beans across this marked area, ensuring 5 beans x
2
=
that they are randomly spread and not stacked 72 cm 7200 cm 2
on top of each other. x = 500 beans.
u Make a quadrat. Students will make a quadrat Using one quadrat in
out of two flexible straws, as shown in the this case reduces the
diagram on the student handout. They are number of calculations
guided to produce rectangular quadrats with involved and makes the
sides between 6 and 10 cm in length. Working numbers easier to work
with. Students are likely
with rectangular quadrats is a way to deepen
to notice that the total
students’ use of mathematical reasoning about plot area in this example
density. To reduce the degree of difficulty, you is 100 times one sample
could have students produce square quadrats quadrat. Help students
(e.g., 10 cm by 10 cm). recognize that when they
move on to working with
u Collect data. Students should complete three
three quadrats, the ratio
separate quadrat sampling events and record
of plot area to quadrat
their data in the table provided on the handout. area will be different.

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 Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Unit 1: Ecological Systems

Key Concept ECO 2: Population Dynamics

DATA COLLECTION FOR QUADRAT SAMPLING SIMULATION HANDOUT
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture
2 Sampling 1.6
Quadrat Area: cm
Total Plot Area: cm 2

Total
u Sampling
Analyze. Area (3 quadrats):
Students cm 2 the average density across all
will use the data to calculate
UNIT 1
three quadrats and the estimated populations, based on the average density. They
Quadrat Sample Red Bean Density White Bean Density
will then do an actual count of the beans, and calculate
(beans / cm2 )
percent error using the
(beans / cm2 )
formula shown here:
1
Experimental − Actual
2
Percent Error = × 100 .
Actual
3
It is important to highlight for students why we are calculating percent error: to
Average Density
get a sense of how accurate the sampling method was during this experiment.
( N / cm 2 )
It can help students identify potential sources of error in this simulation. In an
actual study, it would not be possible to count the individuals, which is why field
DATA ANALYSIS FOR QUADRAT SAMPLING SIMULATION
biologists use population sampling. Calculating percent error is also used here to
develop a general conclusion about the overall accuracy of the method.
Red Bean Population White Bean Population
ƒ To conclude this part of the lab, students will apply their understanding of the
Estimated Population
average density of a population to make predictions about population size in larger
(Experimental Value)
areas. Students will also consider what types of species this particular sampling
Actual Population
method would be best suited for and how the size of the quadrat may impact their
samplingPercent Error See the sample responses to Handout 1.6 shown here.
accuracy.

APPLICATION OF THE QUADRAT METHOD

1. Scientists use the average density found in quadrat sampling of smaller areas to
make predictions about population sizes in areas too large to sample. Use the
average density you found for your beans to calculate predicted population sizes
for the following areas:
(a) What do you predict the red bean population to be in a 3,600 cm 2 area?

Student answers will vary based on their respective average density calculations.
Some students may see that this area is half the size of their original plot and
simply divide the original predicted population by two. Other students may set
up the calculation as:
(N ) beans x
= = x beans
7,200 cm 2 3,600 cm 2

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 Key Concept ECO 2: Population Dynamics
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat
Lesson and Mark−Recapture
1.6: Population Sampling
Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
Unit 1: Ecological Systems

UNIT 1
HANDOUT (b) What do you predict the white bean population to be in a 14,400 cm2 area?
1.6
Student answers will vary based on their respective average density calculations.
Some students may see that this area is twice the size of their original plot and
simply multiply the original predicted population by two. Other students may
set up the calculation as:
(N ) beans x
= = x beans
7,200 cm 2 14,400 cm 2
2. List two additional populations for which this technique would work well. Justify
why this technique is an appropriate choice for the populations you identified.
Students could list a wide variety of species to be sampled. They should highlight
that quadrat sampling really works best with organisms that have limited movement
or are sessile—e.g., corals, sea stars, trees, and wildflowers (plant species in general).

3. Describe how the size of the quadrat would impact population estimates. What
limitations do you think exist for selecting quadrat size for field biologists?
In general, having a larger sampling area would improve accuracy of population size
and density estimates since you are sampling a larger area on which the predictions
are based. However, quadrats must be manageable and easy to move around in the
field in order to do the sample counts, and therefore cannot be too large.

Handout 1.6
Part 2: Mark–Recapture
PART 2: MARK–RECAPTURE
THE MARK–RECAPTURE METHOD
In Part 2 of this laboratory lesson, students are introduced
Ecologists often engageto
inthe mark–recapture
research that seeks
to reveal patterns
method. They think critically about necessary of organism
assumptions in thisabundance
model and and
carry out
distribution.
a simulation. Then they evaluate this method In order toand
by analyzing determine such patterns,
interpreting data.
they need sampling methods that provide
INTRODUCTION TO MARK−RECAPTURE SAMPLING
accurate estimates of the total population of a
ƒ To begin, have students individually read
target introductory
organism. material
This type aboutprovides
of research mark−
recapture sampling and the formula for estimating
valuable information population sizethat
about species using this
is critical
method. Students should continuefor toeffective
use theirresource
readingmanagement.
strategies, such as
Because
underlining key ideas or circling words
Credit: John Van Decker / Alamy Stock Photo
they
counting need
every help defining,
individual in ordercan
in a population to
annotate the text as they go. See Part 2 of Handout
be impractical and 1.6.
very difficult, field biologists
have developed a variety of techniques and

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

UNIT 1 ƒ Explain to students that this sampling method

Meeting Learners’ Needs
involves some assumptions that help ensure the
There are several ways you
validity of the population estimates. For example, can scaffold this reading.
an assumption of mark–recapture is that individuals Some options are:
with marks/tags have the same probability of survival u Students can work with
as other members of the population. Have students a partner after they
work in small groups to brainstorm some other finish reading to share
assumptions and the rationales for each assumption. any words that were not
Students should record these on the table provided familiar and synthesize
on the handout. their notes.
Students could read the
ƒ Once students have had ample time to brainstorm
text aloud as a whole-
important assumptions, have student groups share group discussion,
Lesson 1.6: Populationtheir list.
Field Studies Ensure
Simulations that and
Lab – Quadrat the class identifies
Mark−Recapture Sampling and defines stopping to define words
the assumptions and rationales shown in the handout.
Unit 1: Ecological Systems
together using the
context of the text.
HANDOUT
1.6 Assumptions Rationales

Individuals with marks have the same It is important to choose a marking

probability of survival as other members method that does not harm your animal.
of the population. If a predator used your tagging marks to
locate and capture marked organisms at
a higher rate than other organisms, your
number of recaptures would be lower, and
the estimate would therefore be too high.

Births and deaths do not occur in If marked individuals die and are replaced
significant numbers between the time of with newborns, then you will recapture
release and the time of recapture. few or no marked individuals, and your
estimate will be too high. This is not a large
concern in studies of organisms that breed
slowly, but can significantly affect estimates
for rapidly breeding organisms.

Immigration and emigration do not occur If marked individuals leave the study area
in significant numbers between the time of and new, unmarked individuals come
release and the time of recapture. in to replace them, you will get fewer
recaptures than the equilibrium population
size would lead you to expect. To think
about this another way, the real population
covers a much larger area than the habitat
you thought you were studying.

Marked individuals mix randomly with the If marked organisms do not move
population at large. among unmarked organisms, and you
recapture them near the place you released
them, the recaptured organisms may be
overrepresented in your second sample,
driving down your population estimate.

Marked organisms are neither easier nor If marking an animal frightens it so that
harder to capture a second time. it hides from you a second time, then
recaptures will be underrepresented in
a second sample. If organisms become
tame and are easier to recapture, then the
opposite error is introduced.

Handout 1.6

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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Unit 1: Ecological Systems

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Unit 1: Ecological SystemsUNIT 1

HANDOUT
Assumptions Rationales 1.6

Marks do not come off your marked Invertebrates molt and shed marks,
organisms. mammals can wriggle out of their collars,
and many other things can happen to
obscure your marks. If this happens, HANDOUT
Assumptions Rationales
recaptures will be undercounted, and your 1.6
estimate will be too high.
Marks do not come off your marked Invertebrates molt and shed marks,
organisms.
Recapture rates are high enough to support The Lincoln−Petersonmammals can
calculation tends to wriggle out of their collars,
an accurate estimate. overestimate the population size, especially
and ismany
if the number of recaptures small. other things can happen to
obscure your marks. If this happens,
recaptures will be undercounted, and your
estimate will be too high.

PRACTICING CALCULATIONS FOR MARK–RECAPTURE SAMPLING

Handout 1.6
Recapture
Problem rates
1: Box areSuppose
Turtles. high enough
you want to support
to know how manyThe box Lincoln−Peterson
turtles there are in calculation tends to
aan accurate
wooded estimate.
park. On the first day, you hunt through the woods overestimate the population size, especially
and capture 18 turtles.
Finally,
ƒ You have
place a spot students
of paint work
on each turtle’s shellon
and the
releasetwo
ifpractice
all turtles
theback where
number problems
you for isestimating
of recaptures small. population
found them. A week later you return, and with hard work and effort, catch 50 turtles.
size
Of based
these, on mark−recapture
10 are marked and 40 are unmarked. Sincedata. Students
you know how manyare asked
turtles you to find the estimated
marked, sampled, and recaptured, you can estimate the size of the whole population.
population for the box turtle and leopard frog, given the data in the problems. See
By the definitions above, M = 18 marked and released; S = 50 in the second sample; and
Rstudent solutions shown.
= 10 recaptures.

PRACTICING CALCULATIONS FOR MARK–RECAPTURE SAMPLING

Problem 1: Box Turtles. Suppose you want to know how many box turtles there are in
a wooded park. On the first day, you hunt through the woods and capture 18 turtles.
You place a spot of paint on each turtle’s shell and release all turtles back where you
found them. A week Credit:
later you return, and with hard work and effort, catch 50 turtles.
Phil Degginger / Alamy Stock Photo

Of these, 10 are marked and 40 are unmarked. Since you know how many turtles you
marked, sampled, and recaptured, you can estimate the size of the whole population.
By the definitions above, M = 18 marked and released; S = 50 in the second sample; and
R = 10 recaptures.
Student Resource
© 2021 College Board
33 Pre-AP Biology

BIO_U1_SR.indd 33 24/03/20 9:44 PM

Credit: Phil Degginger / Alamy Stock Photo

Handout 1.6

Teacher Resource
Student Resource 119 Pre-AP Biology TEACH
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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Unit 1: Ecological Systems

UNIT 1 Assuming the second sample is representative of the whole population, use the
HANDOUT
1.6
Meeting Learners’ Needs
Lincoln−Peterson index to find the estimated total population.
10 18
If students struggle with
=
50 N these problems, it’s a good
10 N = 900
idea to debrief together as a
N = 90
whole class to highlight the
Problem 2: Leopard Frogs. A biologist nets 40 leopard frogs from a local pond, tags
purpose of the setup and
them with a microchip, and releases them unharmed. A week later, she nets 65 frogs
from the same pond, including 26 with tags. each calculation. You can
Based on the Lincoln−Peterson index, estimate the number of leopard frogs in the pond. provide a few additional
26 40 practice problems at
=
65 N this point in the class
26 N = 2,600
N = 100 if students need some
more skill-building prior
SIMULATING THE MARK–RECAPTURE METHOD to engaging in the data
During this section of the lab, you and your lab partners will use the mark−recapture
collection and analysis
method to estimate a population. Whereas a fisheries biologist might use this method
to estimate the population of largemouth bass in a pond, you will be using the method portion of the lesson.
to estimate the number of beans in a container.

Handout 1.6, continued

PROCEDURE
Represent the Population

1. Put at least three handfuls of red beans in a container,

Guiding Student Thinking
such as a paper bag. These beans represent unmarked
individuals.
Students can typically memorize or follow a formula to find predicted population sizes.
Olivia Neacsu / 123RF

2. By sight, estimate the population of beans in the

However, they often have trouble connecting what those variables represent and how they
container and write that number down.
may be inaccurate based on the assumptions they listed in their group. Encourage students
to think about which variable(s) would change if these assumptions were not met. For
example: “If marked organisms are easier to find, R would not be accurate and would
likely cause N to be higher than it actually is.”

Pre-AP Biology 34 Student Resource

© 2021 College Board

MARK−RECAPTURE SIMULATION
Now that students have been introduced to the mark−recapture sampling method, they
BIO_U1_SR.indd 34 will simulate a mark−recapture study, again using two different colors of beans. See 24/03/20 9:44 PM

Part 2 of Handout 1.6.

ƒ In the simulation, students will perform the following general steps (described in
greater detail on the student handout):
u Represent the population. Students will use red beans to represent the total
population. To begin, they should place at least three large handfuls of red beans
in a container.

TEACH Pre-AP Biology 120 Teacher Resource

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 Trial S R N

4 Key Concept ECO 2: Population Dynamics

5 Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

7 u Capture and mark. Next, they will capture their first sample (a handful of beans) UNIT 1
8 from the container and record this as the marked individuals in this investigation
(M). These red beans should be replaced with white beans and then returned to
9
the supply table.
10
Recapture. Students should complete 10 sampling trials and record data for the
u

size of each sample (S) as well as the number of marked individuals recaptured
DATA ANALYSIS FOR
(R). For each MARK–RECAPTURE
trial, SIMULATION
they should calculate the population size estimate (N).
u Analyze. Finally, they will calculate the average estimated population after all the
Average Estimated N
trials and the percent error.
ƒ Actual Population
To conclude this part of the lab, students will consider what types of species this
particular
Percent sampling method would be best suited for, and how the time between
Error
recaptures may impact sampling accuracy. Student questions and sample responses
are shown here.
APPLICATION OF THE MARK–RECAPTURE METHOD

1. List two additional populations (other than those listed in the lab) for which
mark and recapture would work well. Justify why this technique is an appropriate
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
choice for the populations you identified.
Unit 1: Ecological Systems
Students may list a wide variety of organisms. However, they should highlight organisms
that have high mobility, for which a quadrat sampling method would be more difficult.

2. Explain how the time between recaptures, in actual field experiments, might HANDOUT
1.6
influence the sampling results.
Student Resource
Pre-AP Biology If the organisms being sampled do not36 have enough time to adequately mix back © 2021 College Board

into the larger population, then the recapture sampling could inflate the population
estimates.

Handout 1.6
BIO_U1_SR.indd 36
Part 3: Comparing Sampling Methods 24/03/20 9:44 PM

Guiding Student
1. In field Thinking
studies, population sampling methods are used to estimate population
size because counting the actual population is not possible. However, in this
At this point, students may be confused about why scientists used the quadrat
experiment, it is useful to see how accurate these sampling methods can be by
method to estimate the elephant population in the HHMI video, instead of mark and
counting the actual populations and calculating the percent error.
recapture. This may be a valuable conversation to have as you discuss the application
questions with your
(a) Discuss students.
which method They should
yielded the see thatpercent
lowest elephants in the wild would be
error.
dangerousAnswers
to mark,will
andvary
therefore each elephant
for each lab group. marked would need to be sedated.
This made an alternative method such as aerial quadrat sampling a better choice.

(b) For each method, identify potential sources of error that may have occurred
during your sampling methods.
Students should identify sources of error such as counting inaccuracy, beans
Teacher Resource 121 or not shaking the container fullyPre-AP Biology
being stacked on one another (quadrat), TEACH
© 2021 College Board
(mark and recapture).

(c) Knowing that there were sources of error in your sampling methods,
describe how field biologists could reduce these sources of error as they
conduct their field sampling.
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 Key Concept ECO 2: Population Dynamics

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling

Unit 1: Ecological Systems

UNIT 1 PART 3: COMPARING SAMPLING METHODS
To conclude this lab, students compare the quadrat and mark−recapture sampling
methods, drawing
2. Explain howonthetheir
timeexperiences runninginthe
between recaptures, twofield
actual simulations. Students
experiments, mightalso HANDOUT
revisit applications 1.6
influence theofsampling
population sampling.
results.
ƒ Have students
If the workbeing
organisms withsampled
their lab
dogroups toenough
not have respond to to
time theadequately
questionsmixin back
Part 3 of
the into the larger
handout. population,
Conclude withthen the recapture
a whole-class sampling in
discussion could inflate
which the population
student groups share
estimates.
and compare their responses.

Part 3: Comparing Sampling Methods

1. In field studies, population sampling methods are used to estimate population
size because counting the actual population is not possible. However, in this
experiment, it is useful to see how accurate these sampling methods can be by
counting the actual populations and calculating the percent error.
(a) Discuss which method yielded the lowest percent error.
Answers will vary for each lab group.

(b) For each method, identify potential sources of error that may have occurred
during your sampling methods.
Students should identify sources of error such as counting inaccuracy, beans
being stacked on one another (quadrat), or not shaking the container fully
(mark and recapture).

(c) Knowing that there were sources of error in your sampling methods,
describe how field biologists could reduce these sources of error as they
conduct their field sampling.
Students should think of how sources of error in their own data collection
could be analogous to situations in the field: field biologists should count twice
or have two counters; for organisms that live in clusters (e.g., corals), biologists
must ensure that all individuals are counted; and the recapture of a mobile
organism should occur after there has been enough time for the organism to
mix back into the original population.

Handout 1.6

Student Resource 37 Pre-AP Biology

TEACH Pre-AP
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Board 122 Teacher Resource
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 Key Concept ECO 2: Population Dynamics
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
Lesson 1.6: Population Field Studies Simulations Lab – Quadrat and Mark−Recapture Sampling
Unit 1: Ecological Systems

2. Compare and contrast the two different methods, giving specific examples of UNIT 1
HANDOUT
1.6
when and why you would use one method over another to assess and predict the
population size of a species.
Students should see that, in general, quadrat studies are best for organisms with
limited or no movement or for mobile animals where it would be too dangerous or
difficult to mark individuals. Mark and recapture is an appropriate survey method
for organisms that have high mobility and are therefore difficult to assess using
traditional quadrat field count sampling.

3. Name and describe at least two applications for population estimates.

Population estimates are used by wildlife management agencies and policymakers
to make informed decisions about protecting wildlife, especially species that are
threatened or endangered.

Handout 1.6, continued

NEXT STEPS
ƒ Field study: Students should now be given the opportunity to practice the sampling
methods learned in this lab in the field. They should design their own experiment
based on techniques learned during this lab. It may be more feasible to conduct a
quadrat survey on school grounds, using PVC pipes or metersticks, than a mark−
recapture survey.

EXTENDING THE LESSON

If students would like to learn more about survey methods for estimating the size of
populations, there is a resource from HHMI BioInteractive called Survey Methods
that allows students to explore other methods being used in Africa to track and
study elephant populations. These methods include aerial surveys, dung transects,
acoustic surveys, and individual registration. This is a self-paced online interactive
activity that can be done either in class or out of class, with a student worksheet
already created to supplement it. Both resources are available at www.hhmi.org/
biointeractive/survey-methods.

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 Key Concept ECO 3: Defining Ecological Communities

UNIT 1 LESSON 1.7

Launch Lesson – Comparing

AREA OF FOCUS
Biomes Using HHMI’s
ƒ Emphasis on Analytical
BiomeViewer Reading and Writing

OVERVIEW
SUGGESTED TIMING
Less than 45 minutes
LESSON DESCRIPTION
This introductory lesson stimulates students to
HANDOUT
begin thinking of biomes in terms of abiotic and
biotic characteristics. Students explore Earth’s ƒ 1.7: Comparing
ecosystems by comparing two biomes, the one Biomes with HHMI’s
where they live and one of their choosing. BiomeViewer

MATERIALS
CONTENT FOCUS
This launch lesson is designed to elicit students’ prior ƒ computers with internet
knowledge about biomes and spark their interest in access, for individual
the importance of biodiversity. As students explore students or groups
the characteristics of different biomes using HHMI’s
BiomeViewer, they begin to develop an understanding
of how abiotic and biotic characteristics are used to define ecosystems.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ The dependence on the availability of abiotic and biotic resources results in

complex and dynamic interactions between organisms and populations.
Learning Objectives Essential Knowledge

ECO 3.2(a) Describe differences in the ECO 3.2.1 Terrestrial biomes are
abiotic and/or biotic factors that shape classified by geographic locations and
aquatic and terrestrial communities. the abiotic factors that shape the unique
ecological communities.
a. Two major abiotic factors that help
define terrestrial biomes include climate
(temperature, precipitation) and soil type.
b. Ecological communities in terrestrial
biomes are shaped by the availability and
abundance of the abiotic factors in that
region.

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 Key Concept ECO 3: Defining Ecological Communities

Lesson 1.7: Launch Lesson – Comparing Biomes Using HHMI’s BiomeViewer

This launch lesson is designed to spark student UNIT 1

Meeting Learners’ Needs
curiosity and appreciation for Earth’s diverse
If students struggle to
ecosystems and biodiversity. A great way to do this is recall characteristics about
using HHMI’s BiomeViewer application. In this lesson, biomes, encourage them to
students use the application to learn a little about both reflect on what they have
the biome where they live and another biome they are observed about their own
interested in. This also elicits prior knowledge from biome—for example, types
middle school life science about topics such as species of trees or annual rainfall.
Then have students extend
diversity and regional temperature and precipitation.
this type of thinking to
ƒ To begin, students should work independently other areas of the world.
to make predictions about the characteristics of
different biomes and how those characteristics
could be used to define unique biomes. See Handout 1.7: Comparing Biomes with
HHMI’s BiomeViewer. To make these predictions, students will likely draw on
prior knowledge from middle school life science.
ƒ Invite students to share their various predictions
Classroom Ideas
about biome characteristics in a whole-class
It is best to have as many
discussion. Encourage students to provide examples biomes explored as possible
for abiotic or biotic features of specific biomes they for the final share-out and
are familiar with. discussion. One idea is
ƒ For the next steps, which students can follow by to assign students a type
of biome for their second
referencing their handout, students will navigate
location and challenge
to the HHMI BiomeViewer website (www.hhmi.
them to find a city in that
org/biointeractive/biomeviewer) and launch the type of biome. There are
application. From here, students first explore their 12 unique biome types
own biome and then explore a different biome that the class can explore.
of their choosing. They will be asked to record
data for each of the two biomes in the data table
provided. Note: The HHMI BioInteractive Biome Viewer works best on a laptop or
desktop computer.
ƒ Once students have finished collecting their data, have them form groups of three
or four to compare their findings. Ideally, each student in the group will have
investigated a different biome. Have student groups consider the questions from the
handout shown on the next page.

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 Key Concept ECO 3: Defining Ecological Communities

Lesson 1.7: Launch Lesson – Comparing Biomes Using HHMI’s BiomeViewer

UNIT 1
Instructional Rationale

Often biome lessons have students utilize maps of different biomes across the world
that have little to no connection to actual data about precipitation and temperatures
or images of the flora and fauna. Therefore, this lesson is designed to engage students
in using and analyzing authentic data aboutLesson 1.7: Launch Lesson – Comparing Biomes Using HHMI’s BiomeViewer
different global biomes and to help them
make explicit connections about how abiotic features influence biotic features. Unit 1: Ecological Systems

4. After you have completed your data collection, discuss the following questions in HANDOUT
1.7
a small group:
Š How did your original thoughts about biomes compare with data collected
during your investigation?
Students should discuss how their original predictions and descriptions compare
with the information collected during the investigation.

Š What abiotic and biotic features help scientists define biomes?

Sample response: Abiotic: Precipitation and climate; Biotic: Vegetation and animal
species diversity

Š Use the data to describe any trends you see between abiotic features and biotic
features. Give specific evidence from your data.
Student answers will vary but should describe how precipitation and climate
influence the type and abundance of animal species.

Š Explain how human activities may have led to species being threatened or
endangered.
Examples could include, but are not limited to, habitat destruction, climate
change, and air and water pollution.

Handout 1.7

ƒ After students have had time for small-group discussion, engage them in a whole-
class debrief. Invite students to share their responses and reasoning to the group
discussion questions.
ƒ As students share their ideas, generate a class list of abiotic and biotic features
for each unique biome. Work together to identify how abiotic features may help
regulate and determine the biotic features for each biome.

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 Key Concept ECO 3: Defining Ecological Communities

Lesson 1.7: Launch Lesson – Comparing Biomes Using HHMI’s BiomeViewer

UNIT 1
Guiding Student Thinking

Students likely have a baseline idea about the type of plants and animals that live in
certain biomes (e.g., rain forest and deserts). However, they may struggle to see how
abiotic factors, such as climate and precipitation, influence what vegetation can live in
these regions and, consequently, what animal species can live in these regions. It might
be helpful to remind students about the influence of abiotic factors on species niche
(from Key Concept ECO 2: Population Dynamics) to make this idea clearer.

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 Key Concept ECO 4: Ecological Community Dynamics

UNIT 1 LESSON 1.8

Launch Lesson – Examining Coral Bleaching Effects

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Students apply proportional reasoning skills and ƒ Strategic Use of
use information drawn from text and graphs to Mathematics
analyze changes in a coral reef ecosystem.
SUGGESTED TIMING
CONTENT FOCUS Less than 45 minutes
In this lesson, students apply proportional reasoning
skills to analyze changes in a coral reef ecosystem, and
HANDOUT
use sentence expansion strategies to draw conclusions
ƒ 1.8: Examining Coral
from data and support or refute a claim. The lesson
Bleaching Effects
serves to introduce or reinforce the concept of complex
community interactions, such as the symbiotic
relationship between coral and the algae in their cells.
This task is ideally used after students have been introduced to the quadrat sampling
method, one of the most common methods of sampling used in ecological studies to
assess species distribution and abundance.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

Learning Objectives Essential Knowledge

ECO 4.2(a) Describe what type of ECO 4.2.1 Competition in ecosystems

symbiotic relationship exists between has led to symbiotic relationships where
two organisms. two or more species live closely together.
ECO 4.2(b) Explain how a symbiotic a. Mutualistic relationships often form
relationship provides an advantage for to provide food or protection for both of
an organism by reducing one or more the organisms involved.
environmental pressures.

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 Key Concept ECO 4: Ecological Community Dynamics

Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects

To begin this lesson, engage students in a whole-class UNIT 1

Meeting Learners’ Needs
guided reading and discussion of a short passage about
Some students may
coral bleaching adapted from NOAA (see the top of struggle with some of
Handout 1.8: Examining Coral Bleaching). This the words in the opening
passage helps establish context for the subsequent text, such as symbiotic or
passage from a research article. Discussion may also zooxanthellae. It will be
unearth student questions or unfamiliar terms that necessary to help students
should be clarified prior to data analysis. define these words prior
to examining the data.
ƒ Next, have students independently read the Coral
Bleaching Study summary on the handout and
closely observe and analyze the data in the graphs.

Instructional Rationale

This lesson is designed to have students think like scientists, as they must extract and
synthesize information both from a reading and from a data display. It is important to
Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects
give students plenty of time to really sit with the data and make observations prior to
Unit 1: Ecological Systems
moving into making analytical inferences.

HANDOUT
1.8 2004 3%
2007
Types of Coral
10% Bleached
18% 23%
9% Brain
35%
Staghorn
5% 13%
Finger
26%
Tree
25% 14%
19% Crystal

Adapted from Zaki (student researcher), “Resilience of a Red Sea Fringing Coral Reef Under Extreme
Environmental Conditions: A Four Year Study.” © 2008 by the American Museum of Natural History.
www.amnh.org.

Handout 1.8

Check Your Understanding

ƒ Engage students in a whole-class discussion of their initial observations about the
data. Prompts to promote student thinking may include:
1. Describe the ecological relationship between the coral and the zooxanthellae algae.
u What similarities and differences do you notice first between the two data
Coral and the algae zooxanthellae are symbiotic with each other. The algae provide
collections?
the coral with nutrients to grow. (Note: At this point students are being introduced
u What doesofa symbiosis,
to the idea recorded percentage for a species
so it is not important in thetodata
for them set actually
identify mean?
mutualism or
what the algae is gaining in return. However, you could extend this question during
discussion.) TEACH
Teacher Resource 129 Pre-AP Biology
© 2021 College Board
2. How many quadrats were needed to examine the percent coverage of the coral
species across the 18 m 2 covered during the transect of the reef?

1.5 m(1.5 m) = 2.25 m 2 ; 18 m 2 /2.25 m 2 = 8 quadrats

BIO_U1_TR.indd 129 3. How many square meters does the crystal coral cover in the experimental sample 13/04/20 9:33 PM
 Key Concept ECO 4: Ecological Community Dynamics

Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects

UNIT 1
u Why would scientists want to record the percentage of bleached corals in their
samples?
u Why was it important to collect data from the same 18 m 2 of the reef in both 2004
and 2007?
ƒ Next, have students work in pairs to answer the Check Your Understanding
questions about changes in species composition in the reef.
Question 6 asks students to use the sentence expansion routine to “craft three separate
sentences to support or refute this scientist’s claim” using evidence from the data.
Students may need help crafting their initial independent clause and expanding their
sentences
Lesson 1.8: Launch Lesson to incorporate
– Examining Coral Bleachingevidence
Effects from the data.

ƒ Once
Unit 1: Ecological Systemspairs have finished answering the questions, have them get together in larger
groups to share and revise their sentence expansions. Groups should collaborate to
develop final sentences to refute or support the scientist’s claim.
HANDOUT
1.8 2004 2007
Guiding Student3%
Thinking Types of Coral
10% Bleached
18% students
Sometimes 23%have difficulty crafting strong scientific claims based on evidence
9% Brain
from data. Therefore they will use the sentence expansion
35% approach to focus on
Staghorn
writing one sentence 5%
at a time to help
13%scaffold their thinking. If students struggle
Finger
getting started with their sentences, have them return to the initial observations and
26%
Tree
inferences made25%
about the data together14%as a class to help guide their writing.
19% Crystal

ƒ Adapted from
To close Zaki
the (studentengage
lesson, researcher), “Resilience
students in aof whole-class
a Red Sea Fringing Coral Reef of
discussion Under Extreme
evidence-based
Environmental Conditions: A Four Year Study.” © 2008 by the American Museum of Natural History.
claims. Invite student pairs/groups to share their sentences, and encourage peer-to-
peer feedback on statements.

Check Your Understanding

1. Describe the ecological relationship between the coral and the zooxanthellae algae.
Coral and the algae zooxanthellae are symbiotic with each other. The algae provide
the coral with nutrients to grow. (Note: At this point students are being introduced
to the idea of symbiosis, so it is not important for them to identify mutualism or
what the algae is gaining in return. However, you could extend this question during
discussion.)

2. How many quadrats were needed to examine the percent coverage of the coral
species across the 18 m 2 covered during the transect of the reef?

1.5 m(1.5 m) = 2.25 m 2 ; 18 m 2 /2.25 m 2 = 8 quadrats

Handout 1.8
3. How many square meters does the crystal coral cover in the experimental sample
TEACH Pre-AP Biology
(18 m2) in 2007? 130 Teacher Resource
© 2021 College Board
2 2
10% = 0.1; 0.1(18 m ) = 1.8 m

4. If the percent of crystal coral coverage in 2007 remained constant for the entire
reef, how many square meters of crystal coral coverage would you expect for an
BIO_U1_TR.indd 130 area of reef totaling 100 m2? 13/04/20 9:33 PM
 1. Describe the ecological relationship between the coral and the zooxanthellae algae.
Coral and the algae zooxanthellae are symbiotic with each other. The algae provide
the coral with nutrients to grow. (Note: At this point students are being introduced
to the idea of symbiosis, so it is not important for them to identify mutualism or
what the algae is gaining in return. However, you could extend this question during
discussion.)
Key Concept ECO 4: Ecological Community Dynamics
2. How many quadrats were needed to examine the percent coverage of the coral
Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects
2
species across the 18 m covered during the transect of the reef?

1.5 m(1.5 m) = 2.25 m 2 ; 18 m 2 /2.25 m 2 = 8 quadrats

3. How many square meters does the crystal coral cover in the experimental sample UNIT 1

(18 m2) in 2007?

10% = 0.1; 0.1(18 m 2) = 1.8 m 2

4. If the percent of crystal coral coverage in 2007 remained constant for the entire
reef, how many square meters of crystal coral coverage would you expect for an
area of reef totaling 100 m2?
Lesson 1.8: Launch Lesson – Examining Coral Bleaching Effects
10% = 0.1; 0.1(100 m 2) = 10 m 2
Unit 1: Ecological Systems
5. What percentage of the entire reef did the scientists sample?

18 m 2 /360 m 2 = 0.05(100) = 5%
6. When asked about the shift in biodiversity of coral in the reef system from HANDOUT
1.8
2004 to 2007, a marine ecologist stated, “The shift in biodiversity really isn’t too
Pre-AP Biology 44 Student Resource
surprising given that brain coral is a hardier species, whereas staghorn is much © 2021 College Board

more vulnerable to stressful environmental conditions. I believe staghorn will

continue to decline in percent coverage.”
Craft three separate sentences to support or refute this scientist’s claim. Use the
BIO_U1_SR.indd 44
following sentence expansion routine: 24/03/20 9:45 PM

Š Start with a short statement that you generate from the data.
Š Expand that statement into three different sentences, using the conjunctions
because, but, and so.
Š Each sentence should use available data to support or refute the scientist’s claim.
Sample response:

Initial statement: Staghorn is not as hardy as brain coral.

ƒ Staghorn is not as hardy as brain coral because when stressful conditions
increased, it decreased in percent coverage by 44%.
ƒ Staghorn is not as hardy as brain coral, but it is still the second-most
abundant species in the reef.
ƒ Staghorn is not as hardy as brain coral, so I think brain coral will continue
to have more percent coverage than staghorn while the reef is under
stressful conditions.

7. Predict what changes in the reef ecosystem might occur if coral continue to
decline.
Student answers will vary, but students should lean on prior knowledge of food webs
to explain that the coral is a food source for organisms and therefore there would be
a disruption in the food web. Also, it serves as a habitat to many organisms who may
not survive without the coral.
Handout 1.8

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 Key Concept ECO 4: Ecological Community Dynamics

UNIT 1 LESSON 1.9

Modeling the Importance of Keystone Species

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Part 1: Developing a Model of the Badlands ƒ Attention to Modeling
National Park Food Web ƒ Emphasis on Analytical
The first part of this lesson introduces students Reading and Writing
to the idea of a keystone species. It also revisits
concepts of food webs by having students develop
SUGGESTED TIMING
a model of a food web for specific organisms in
~90 minutes
Badlands National Park.

Part 2: Using the Model to Make Predictions HANDOUTS

Students revise the models they created in Part 1
ƒ 1.9.A: Modeling
of this lesson to predict what changes could
the Importance of
occur if the prairie dog were removed from the
Keystone Species
ecosystem. Students then evaluate each other’s
ƒ 1.9.B: Species Cards
models.
for Modeling the
Importance of
CONTENT FOCUS Keystone Species
This lesson builds on and extends student
understanding of the flow of energy through predator– MATERIALS
prey interactions in an ecosystem. Students read an
One of the following
article and develop a model of the food web in South
sets of items for model
Dakota’s Badlands National Park by interpreting
development:
information on provided species cards. As they develop
their models, students reinforce concepts about ƒ poster paper, markers,
the ecological roles of organisms and interspecific scissors, and tape
competition in ecological communities. By using their ƒ mini-whiteboards,
models to predict what disruptions could occur in this markers, scissors, and
community if the prairie dog were removed, students tape
develop an authentic understanding of what a keystone ƒ computer modeling
species is and its importance in maintaining ecosystem tool (e.g., SageModeler)
dynamics.

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Lesson 1.9: Modeling the Importance of Keystone Species

COURSE FRAMEWORK CONNECTIONS UNIT 1

Enduring Understandings

ƒ The dependence on the availability of abiotic and biotic resources results in

complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

Learning Objectives Essential Knowledge

ECO 4.1(c) Create and/or use models to ECO 4.1.1 Competition between
explain predictions about the possible species drives complex interactions in
effects of changes in the availability of ecosystems.
resources on the interactions between a. Predator and prey populations
species. respond dynamically to each other.
b. Keystone species have a dramatic
impact on the structure and diversity
of ecological communities (e.g., trophic
cascade).

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Lesson 1.9: Modeling the Importance of Keystone Species

UNIT 1 PART 1: DEVELOPING A MODEL OF THE BADLANDS NATIONAL PARK

FOOD WEB
The first part of this lesson introduces students to the idea of a keystone species. It also
revisits the concept of food webs by having students develop a model of a food web for
specific organisms in Badlands National Park.

First, have students read a short passage about

Lesson 1.9: Modeling the importance
the Importance of Keystone Speciesof the prairie dog

in the Badlands National Park ecosystem (see Handout 1.9.A: Modeling the
Unit 1: Ecological Systems

Importance of Keystone Species).

Modeling the Importance of Keystone Species HANDOUT
1.9.A

“Look at that landscape out there,” said Dr. Glenn E. Plumb, Classroom Ideas
the wildlife biologist for Badlands National Park, as he gazed
out across the prairie-dog town. “That’s a real concentration of It may be helpful to show
biological activity, a lot of complex nature.” students some images of
Its verdant carpet produces more new growth in a given year than the Badlands National Park
is produced in similarly sized patches of the surrounding plains,
attracting a crowd of plant and seed eaters from insects to mice to
in South Dakota. Most
birds to bison. Predators like hawks, coyotes, and bug-eating birds students are not aware that
follow.
this park contains one of
The prairie dogs, as architects and custodians of their immediate
the richest mammal fossil
environment, are largely responsible for this concentration of life.
Their constant cropping of vegetation stimulates faster and more beds in the world, with
nutritious growth, while their burrows provide homes and hunting fossils of saber-toothed
grounds for many organisms, large and small. The resulting
patches of habitat make the Plains ecosystem more complex,
tigers and rhinos. The
diverse and biologically active than it would otherwise be. Badlands National Park
Adapted from William Stevens, “Prairie Colonies Bolster Life in the Plains.”
© 1995 by The New York Times Company. website (www.nps.gov/
badl) features photo
Wildflowers Golden Eagle Desert Pocket American Bison Western
Mouse Wheatgrass galleries and virtual
field trip resources to
share with students.
Black-Tailed Blue-Legged Plains Coyote Prairie
Prairie Dog Grasshopper Rattlesnake

Common organisms in the Badlands National Park ecosystem

Handout 1.9.A

ƒ Once students have read the passage, engage the whole class in a discussion of it
and the accompanying figure to elicit students’ prior knowledge about the flow
of energy in terrestrial food
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Pre-AP Biology

for the upcoming modeling handout. Some prompts to promote discussion and
student thinking are:
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Lesson 1.9: Modeling the Importance of Keystone Species

u What images come to mind when you think of a prairie? UNIT 1

Responses will vary, but students may indicate that these ecosystems are
dominated by small or tall grasses and shrubs rather than trees. Students often
describe grasslands as “open” due to the scarcity of trees.
u What evidence from the opening text supports the author’s description of prairie
dogs as “architects and custodians” of their environment?
Look for student responses that point to how prairie dogs serve as “architects” by
constructing tunnels. These tunnels provide both homes and “hunting grounds”
for a multitude of organisms. Similarly, students should point out that prairie
dogs serve as “custodians,” helping to maintain their environment, through
“constant cropping of vegetation,” which stimulates plant growth. Students
might thread in supporting information from earlier in the excerpt, including
the descriptions of the national park as a “prairie-dog town” and of the grass as a
“verdant carpet.”

ƒ Next, students will work in pairs to develop a model of the food web in this prairie
ecosystem, using the provided species cards from Handout 1.9.B: Species Cards
for Modeling the Importance of Keystone Species. Students can use classroom
reference materials, including their textbooks, as well as online resources for
additional support in developing their models.
Models can be built in various ways, including with large poster paper, on mini-
whiteboards, or using technology. Students should provide evidence from their
resources to support each organism’s role as shown in their model. Students should
also use appropriate terminology to label each organism’s ecological role (e.g., apex
predator, primary producer).

Instructional Rationale

The species cards are designed to allow for some student choice in creating the
model. For example, the species card for the prairie rattlesnake indicates it does eat
small mammals and uses the prairie dog’s den for hunting, but doesn’t specifically
reference preying on the prairie dog. This ambiguity requires students to make
some assumptions based on the available information, just as scientists also make
assumptions when modeling a natural phenomenon. These assumptions help facilitate
productive peer-to-peer discussions when students evaluate each other’s models.
This type of development and revision process leads to much deeper conceptual
understanding than more traditional rote memorization and filling in models that are
already populated for them.

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Lesson 1.9: Modeling the Importance of Keystone Species

UNIT 1 ƒ After student pairs have completed their models, lead another whole-class
discussion to assess student thinking about some basic components of the food web
model. Some possible questions to ask are:
u What organism(s) serve as the base for this prairie food web?
wildflowers, wheatgrasses
u Which organisms in the food web have more than one consumer feeding
upon them?
desert pocket mouse, prairie dog, wheatgrasses, wildflowers
u What are the benefits to being able to feed on more than one type of prey?
Being able to consume a wider range of prey typically increases an organism’s
chance for survival since it is not dependent on the survival of a single prey
species.
u When an organism eats prey, why doesn’t the organism gain all the energy stored
in the prey’s body?
As energy flows through the food web, from one trophic level to the next, only
about 10% of the energy from consuming prey is stored as body tissue. The
remaining energy is primarily “lost” as heat given off during metabolic processes.

PART 2: USING THE MODEL TO MAKE PREDICTIONS

In this part of the lesson, students use their models to consider what changes would
occur in this ecosystem if the prairie dog were removed.

ƒ To begin, student pairs create a list of disruptions that may occur to the food web if
the prairie dog is no longer in the ecosystem. See Part 2 of Handout 1.9.A.

Guiding Student Thinking

Students may easily see some direct impacts of the removal of the prairie dog, such as
top predators (e.g., plains coyote, golden eagle, and prairie rattlesnake) not having a
main prey source. However, they should be pushed to think about indirect disruptions
as well. For example, if prairie dogs are not there to stimulate growth of the grasses, as
students learned in the excerpt, then species that depend on grasses (e.g., American
bison, blue-legged grasshopper) will suffer. Also, the rattlesnakes use the prairie dogs’
dens for hunting other small prey; without these dens, the snakes would be less effective
at hunting. It’s important that students recognize the wide variety of disruptions to the
community that could be caused by the removal of the prairie dog. This recognition
helps solidify the concept of a keystone species’ impact on its ecosystem.

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Lesson 1.9: Modeling the Importance of Keystone Species

ƒ Next, have each student pair work with another UNIT 1

Meeting Learners’ Needs
group to evaluate each other’s models and compare
Some students may
and contrast lists of food web disruptions. The struggle to give critical
peer-to-peer dialogue should lead to students feedback on their peers’
critiquing each other’s models and prompt groups models. If students need
to consider revisions. Monitor student discussions support, you can have
to provide appropriate feedback and guidance on them use some sentence
their predictions, explanations, and connections. frames that help with
giving feedback, such as:
ƒ Finally, facilitate a whole-class discussion on the
Can you explain why there
possible ecosystem changes that could take place
is a relationship between
if the prairie dog were removed from the Badlands and .
National Park ecosystem. A class list of disruptions
should be generated using student models and
predictions. Have students develop their own definition of a keystone species based
on how their models illustrate the changes that could occur in an ecosystem when a
keystone species is removed.

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 Key Concept ECO 5: Changes in Ecological Communities

UNIT 1 LESSON 1.10

Launch Lesson – Invasive Species—

Brown Tree Snakes in Guam

OVERVIEW

LESSON DESCRIPTION AREAS OF FOCUS

Students work in small groups to draw ƒ Emphasis on Analytical
conclusions about the brown tree snake—an Reading and Writing
invasive species in Guam—based on information ƒ Strategic Use of
in clue cards. Then, students share answers in a Mathematics
whole-group discussion and make connections to
invasive species in their local environment. SUGGESTED TIMING
Less than 60 minutes
CONTENT FOCUS
This lesson engages students in thinking about HANDOUTS
how even small changes in the natural processes
ƒ 1.10.A: Brown Tree
of ecological communities can result in major
Snake Clue Cards
consequences. Students explore this idea through the
ƒ 1.10.B: Drawing
phenomenon of an invasive species, the brown tree
Conclusions About
snake in Guam, and analyze text and data in order
Brown Tree Snakes
to make claims and predictions about this invasive
species.

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Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree Snakes in Guam

COURSE FRAMEWORK CONNECTIONS UNIT 1

Enduring Understandings

ƒ Changes to the environment can alter interactions between organisms.

Learning Objectives Essential Knowledge

ECO 5.2(a) Use evidence to support the ECO 5.2.1 Human activities (e.g.,
claim that changes in ecosystems have urbanization, farming, tree harvesting)
resulted from human activities. also alter availability of nutrients, food,
ECO 5.2(b) Given a human activity, and niches for species and therefore
predict the potential biological affect population and community
consequences for an ecosystem’s dynamics.
biodiversity. a. Human activities include
anthropogenic climate change, the
introduction of invasive species, habitat
destruction, and air/water pollution.
b. The effects of human-induced
environmental changes and their impact
on species are the subject of a significant
amount of current scientific research.

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Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree Snakes in Guam

UNIT 1 Students may be familiar with invasive species that live in their area or with invasive
species that are more common, or “famous,” across the globe. This lesson is designed
to have students apply Key Concept ECO 4: Ecological Community Dynamics to a
common ecological problem, the introduction of invasive species, to explore how
ecological processes may be altered through human activity. Students use textual and
graphical evidence from clue cards to form inferences about the ecological impact
of the invasive brown tree snake.
EXPLORING IMPACTS OF AN INVASIVE SPECIES
ƒ Show students a picture of an invasive brown tree
Classroom Ideas
snake in Guam, such as the one below. Engage
It may be helpful to show
students in a brief discussion about invasive a map of where Guam is
species. To help promote thinking about invasive located in relation to the
species, the following prompts may be helpful: native regions of the brown
u Why do you think the term invasive is used for tree snake (northeastern
Australia, eastern
these species?
Indonesia, and Melanesia).
u How do these species get to new ecosystems?

Credit: Photo of Brown Tree Snake. © 2012 by Pavil Kirillov. CC BY 2.0. https://flic.kr/p/dMbxtN.

Guiding Student Thinking

Some students may not realize that invasive species are species that have been
introduced into a new environment where they are not native organisms. In this
new environment, invasive species may have few if any natural predators and their
populations can increase rapidly. Sometimes, this rapid population increase can cause
ecological damage as well as economic problems. Students may not fully understand
that these same species in their native ecosystems are not invasive. Therefore, it may be
helpful to remind them that invasive species are also referred to as nonnative species.

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Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree Snakes in Guam

ƒ For this investigation of how invasive species UNIT 1

Classroom Ideas
impact their new ecosystems, have students work
You may want to cut out
in pairs or small groups. To begin, give students the clue cards and laminate
time to read an excerpt from an NBC News article them or glue them on to
about Guam’s efforts to eradicate the brown tree stiff paper, particularly if
snake. See Clue Card 1: Mice Dropped on Guam you plan to reuse the cards
by Parachute from Handout 1.10.A: Brown Tree for multiple class sections.
Snake Clue Cards.
ƒ The excerpt tells us that Guam is on a mission to kill off the brown tree snake,
but why? Have groups brainstorm how an invasive species, such as the brown tree
snake, may cause severe disruption to natural ecological systems. As groups are
working, you may need to circulate around the room and promote critical thinking
with the following prompts:
u How could the introduction of a new species
Meeting Learners’ Needs
affect the local food web?
To ensure that all students
u What species would be most likely to cause a feel they can engage with
disruption? Explain your response. this text, you may want
u Do you think native species would only decline to read the first clue card
together and discuss
or would some flourish? Why?
some of the challenging
ƒ Next, have students closely observe and analyze the vocabulary together
graphs of data on bird populations on Guam, from before moving on.
Clue Card 2: Data on Bird Populations on Guam
from 1976 to 2000. Ask students to consider the
following questions as they examine the graphs:
u Do all bird species seem equally at risk for decline?
u What characteristics might the birds have that help protect them or place them
more at risk?
u During what years do you see most species start to decline?
u What overall trend statement could you make about the impact of the brown tree
snake on bird populations in Guam?

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Lesson 1.10: Launch Lesson – Invasive Species—Brown Tree Snakes in Guam

UNIT 1
Guiding Student Thinking

Students should predict that some birds are more prone to decline than others.
Students may need help identifying characteristics that affect populations’ risk of
decline. Some characteristics to discuss with the class include the following:

Characteristics of Birds Most at Risk Characteristics of Birds Least at Risk

ƒ Live in forests ƒ Live in cities

ƒ Smaller size (may be easier to ƒ Larger size (may be more
prey upon) difficult to prey on)
ƒ Produce few offspring per clutch ƒ Produce more offspring per
(the group of eggs in each nest) clutch

ƒ Finally, have students read about recent research on indirect impacts of Guam’s
brown tree snakes. See Clue Card 3: Guam Could Lose More Than Its Birds.
Students should then work together on a question set that will help them
synthesize their thoughts across all three clue cards. See Handout 1.10.B: Drawing
Conclusions About Brown Tree Snakes.
WHOLE-CLASS DISCUSSION
ƒ Once students have completed the clue card handout in their groups, engage them
in a whole-class discussion about invasive species in your area, as well as famous
examples in the world (e.g., zebra mollusks, cane toads, Asian carp, lionfish, kudzu,
Africanized bees, and fire ants). If you are not familiar with local invasive species,
you can go to www.iucngisd.org/gisd/ to find an extensive list.
ƒ As a class, debrief on the groups’ answers to the question set on the handout.
Sample answers are provided on the next page for reference.

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Lesson 1.10: Launch

Lesson Lesson
1.10: Launch – Invasive
Lesson Species—Brown
– Invasive TreeSnakes
Species—Brown Tree Snakes in Guam
in Guam

Unit 1: Ecological Systems

UNIT 1
Drawing Conclusions About Brown Tree HANDOUT
1.10.B
Snakes

1. The brown tree snake is native in areas such as Australia and eastern Indonesia. In
those ecosystems, the brown tree snake is not causing the decline of bird or tree
populations. So what makes this same species damaging in Guam? Identify some
characteristics a species may possess that would fuel its ability to cause ecological
damage, as the brown tree snake has in Guam. Provide some reasoning for why
you chose these characteristics.

ƒ Outcompete native species.

ƒ Have no natural predators.
ƒ Are generalists that can eat many things and live in many different habitats.

2. Make a list of ecological consequences that you can infer have occurred on Guam
due to the introduction of the invasive (nonnative) brown tree snake.

ƒ Overall decline in bird populations.

ƒ Birds scatter seeds after they eat them, so fewer birds means fewer seeds are
dispersed.
ƒ Birds eat insects, so fewer birds mean more insects; more insects may lead
to increased insect-borne diseases in humans and animals.

Handout 1.10.B

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.10:
Lesson Launch
1.10: LaunchLesson
Lesson ––Invasive
Invasive Species—Brown
Species— Tree Snakes
Brown Tree Snakes in Guamin Guam

Unit 1: Ecological Systems

UNIT 1
HANDOUT 3. On the first clue card, you learned how scientists are trying to control the snakes
1.10.B
by dropping acetaminophen-laced mice into Guam to kill the snakes. Do you
think we should get involved in cases like this to try to fix problems that we
started? Can you think of any problems that might happen because of humans
trying to fix the original problems?

ƒ Nonnative species being brought in by humans to stop another invasive

species may also damage the ecosystem.
ƒ Other animals getting harmed in the process of removing the targeted
animal.

4. According to the article, there are 3,000 brown tree snakes in Guam per square
mile ( mi 2 ) . The average high school in the United States is approximately
121,000 square feet or 0.004 square miles ( mi 2 ) . According to these numbers, how
many brown tree snakes would be found in an area the size of a typical U.S. high
school?
3,000 snakes 0.004 mi 2 12 snakes
× =
mi 2 school school

Handout 1.10.B

Guiding Student Thinking

This part of the lesson is an excellent opportunity for students to practice the critical
skill of working with multiple units to solve a problem (dimensional analysis).
However, students may struggle with starting the problem. Encourage students to
identify the units needed in the answer (“snakes per school”). Then have them work
backward and set up the problem to compare the right units in order to end with what
they need.

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 Key Concept ECO 5: Changes in Ecological Communities

LESSON 1.11 UNIT 1

Predicting Changes in Arctic Ecological

Communities

OVERVIEW

LESSON DESCRIPTION AREAS OF FOCUS

Part 1: Examining Data on Arctic Sea Ice Extent ƒ Emphasis on Analytical
Students use data from a graph to observe and Reading and Writing
analyze changes in Arctic sea ice extent. ƒ Strategic Use of
Part 2: Making Predictions and Asking Mathematics
Scientific Questions
Students use information about Arctic species SUGGESTED TIMING
to make predictions about changes in this Arctic ~60 minutes
community and to ask scientific questions.

Part 3: Summary HANDOUTS

Students share their predictions and scientific ƒ 1.11.A: Predicting
questions in a whole-class discussion. Students Changes in
also consider how small changes in their daily Arctic Ecological
activities could curb contributions of carbon Communities
dioxide. ƒ 1.11.B: Arctic Species
Information Cards, one
CONTENT FOCUS set of cards cut out per
Ecological communities face both natural and student pair
unnatural (human-induced) changes that alter
ecological processes. Students make connections to Key MATERIALS
Concept ECO 1: Cycling of Matter in the Biosphere and ƒ internet access and
other key concepts as they examine how changes to the LCD projector,
climate affect Arctic sea ice extent and, consequently, electronic whiteboard,
the local ecological community that depends on the or other technology
sea ice. for displaying images
showing Arctic sea ice
extent (optional)
ƒ rulers

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.11: Predicting Changes in Arctic Ecological Communities

UNIT 1 COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Changes to the environment can alter interactions between organisms.

Learning Objectives Essential Knowledge

ECO 5.2(a) Use evidence to support the ECO 5.2.1 Human activities (e.g.,
claim that changes in ecosystems have urbanization, farming, tree harvesting)
resulted from human activities. also alter availability of nutrients, food,
ECO 5.2(b) Given a human activity, and niches for species and therefore
predict the potential biological affect population and community
consequences for an ecosystem’s dynamics.
biodiversity. a. Human activities include
anthropogenic climate change, the
introduction of invasive species, habitat
destruction, and air/water pollution.
b. The effects of human-induced
environmental changes and their impact
on species are the subject of a significant
amount of current scientific research.

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Lesson 1.11: Predicting Changes in Arctic Ecological Communities

PART 1: EXAMINING DATA ON ARCTIC SEA ICE EXTENT UNIT 1

In this first part of the lesson, students read an excerpt about changes in Arctic sea ice.
They then analyze and interpret data from a graph to make predictions.

ƒ First, have students closely observe and analyzeLesson 1.11: Predicting Changes in Arctic Ecological Communities
an introductory paragraph and
graph about changes in Arctic sea ice extent. See Part 1 of Handout 1.11.A: Unit 1: Ecological Systems
Predicting Changes in Arctic Ecological Communities. The graph, included
here, shows the annual minimum Arctic sea ice extent, measured each year in
Predicting
September. StudentsChanges inrulers
may want to use Arctic Ecological
in order to make better estimates of HANDOUT
1.11.A
Communities
data points on the graph.

Part 1: Examining Data on Arctic Sea Ice Extent

Arctic sea ice, the layer of frozen seawater covering much of the
Arctic Ocean and neighboring seas, is often referred to as Earth’s
air conditioner: its white surface bounces solar energy back to
space, cooling the globe. The sea ice cap changes with the season,
growing in the autumn and winter and shrinking in the spring
and summer. Its minimum summertime extent (how much
surface area it covers), which typically occurs in September, has
been decreasing, overall, at a rapid pace since the late 1970s due
to warming temperatures.

8
Sea ice minimum (million km2)

3
1980 1985 1990 1995 2000 2005 2010 2015 2020
Year

Arctic sea ice minimum extent in September (1979−2019). (Text and graph adapted from “End-of-Summer
Arctic Sea Ice Extent Is Eighth Lowest on Record.” © 2019 by NASA.)

1. 1.11.A
Handout Calculate the percent change in the area of September Arctic sea ice extent
between 1980 and 2019.

( 4.2 million km 2
− 8 million km 2 )
× 100 = −47.5%
8

2. Determine the average change in Arctic sea ice extent per decade.
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1 decade −47.5% −12.2%
2019 − 1980 = 39 years × = 3.9 decades ∴ =
10 years 3.9 decades decade

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.11: Predicting Changes in Arctic Ecological Communities

UNIT 1 ƒ After students have analyzed the paragraph and

Classroom Ideas
graph on their own, lead a whole-class discussion
It may be helpful to have
to orient students to the graph, using questions students see a visual
such as the following: representation of the
u Based on the introductory text, what does extent changing surface area
mean? of sea ice in the Arctic.
NASA’s Climate Change
The surface area (coverage) of sea ice over the website (https://climate.
Arctic. nasa.gov/) provides a
u What measurement on the graph provides digital interactive that you
can explore with students.
evidence that surface area is being measured?
By expanding the Arctic
The y-axis is in millions of square kilometers Ice Minimum tab, you can
(km 2 ) and square kilometers is a measure of area play a time-lapse video
(km × km). or drag the slider to see
changes in Arctic sea ice
u What does one data point on this graph extent from 1979 to 2018.
represent?
Each data point represents the total surface Meeting Learners’ Needs
area (million km 2 ) of Arctic sea ice, recorded in Some students may need
September of each year. additional support in
working through this
ƒ Next, to prompt students to think about the overall
math. If so, it might be
trend in Arctic sea ice extent and its importance best to do an example
to organisms in the Arctic ecosystem, have each as a class prior to them
student work with a partner to answer the data getting started. For
analysis questions on the handout. example, analyze the
percent change in the
area from 1978 to 1995.
6 million km 2 − 7 million km 2
6 million km 2
× 100 = − 16.7%

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 7

Sea ice minimum (million

6

3
1980 1985 1990 1995 2000 2005 2010 Key Concept
2015 2020ECO 5: Changes in Ecological Communities
Year
Lesson 1.11: Predicting Changes in Arctic Ecological Communities
Arctic sea ice minimum extent in September (1979−2019). (Text and graph adapted from “End-of-Summer
Arctic Sea Ice Extent Is Eighth Lowest on Record.” © 2019 by NASA.)

UNIT 1
1. Calculate the percent change in the area of September Arctic sea ice extent
between 1980 and 2019.

( 4.2 million km 2
− 8 million km 2 )
× 100 = −47.5%
8

Lesson 1.11: Predicting Changes in Arctic Ecological Communities

2. Determine the average change in Arctic sea ice extent per decade.
Unit 1: Ecological Systems
1 decade −47.5% −12.2%
2019 − 1980 = 39 years × = 3.9 decades ∴ =
10 years 3.9 decades decade

HANDOUT 3. Predict which organisms may depend on Arctic sea ice.

1.11.A
Student Resource
Sample response: Polar bears, orcas, or walruses. (Note: Penguins do not live in
59 Pre-AP Biology
© 2021 College Board the Arctic; furthermore, they are found in the Southern Hemisphere .)

Handout 1.11.A

Part 2: Making Predictions and Asking Scientific Questions

ƒ When students have finished, have volunteers share and explain their answers to
BIO_U1_SR.indd 59 24/03/20 9:46 PM
THE
the IMPORTANCE OF ARCTIC
class. It would also be helpfulSEA ICE the worked problems on the board so
to show
You may remember
students from
can see the studying
steps of thethe carbon cycle
calculations forthat humans’
each energy use has
answer.
contributed greatly to the amount of carbon dioxide found in the atmosphere.
According to NASA, “Humans have increased atmospheric CO2 concentration by more
Guiding Student Thinking
than a third since the Industrial Revolution began. This is the most important long-
lived
The ‘forcing’
ability of climate
to calculate change.”
percent The warming
change of Earth’s
is a necessary skillglobal climate
for data has While
analysis. negative
students should
effects on Arctichave prior
sea ice experience,
extent from middle
and, consequently, on school, using percentages to solve
Arctic ecosystems.
problems, they may need a bit of help getting started. As you monitor students working
Predators have a significant impact on the structure and stability of ecosystems. As
on their calculations, some helpful hints and examples for students may include:
you previously learned, trophic cascades are ecological phenomena that occur when
ƒ A percent
predator changeaffect
populations represents the change
the populations of that hasthroughout
species occurred in a quantity
their over
food webs,
time, normalized
controlling the size andasbehavior
a percentage
of prey(out of 100). Trophic cascades significantly
populations.
ƒ Percent
impact change
resource is calculated
availability, by finding
nutrient cycling,the difference
and, between
in turn, entire the final The
ecosystems. and area
initial
quantities, dividing the difference by the initial quantity, and multiplying
of the Arctic that is seasonally covered with sea ice is rapidly changing. These changes by 100.
are
ƒ Ahaving profound
negative valueeffects on predator
indicates that the populations, and the resulting
quantity decreased, trophic cascades
while a positive value
are indicates thatcharacteristics
changing the the quantity increased.
of life in theFor example:
Arctic.
If $1,000
In theuArctic, sea is
icedeposited in a bank
provides critical account
habitat and after one
for numerous yearPredators
species. the balance
suchis as
$1,050, the percent change is calculated as follows:
polar bears use sea ice as a platform for hunting seals and small whales. Polar bears
hunt by lying in wait at the edge −of1,000)
(1,050 sea ice or near holes in sea ice until these marine
× 100 = 5% , or a 5% increase.
mammals risk exposing themselves 1,000to come up for air. Moreover, many seal species rely
If the
on seau ice as apopulation
resting placeofand
snails
as ainnursery
a garden
forwas
their350 five years ago and is 50 today,
young.
the percent change is calculated as follows:
For some other species of marine mammal, sea ice serves as an obstacle, limiting
(50 − 350) whales that are too big to breathe through the
the amount of available habitat. Large× 100 = − 600% , or a 600% decrease.
50
relatively small holes in sea ice, as well as whales with large dorsal fins that don’t fit
through the holes in sea ice, such as killer whales, cannot travel easily in an ocean
Teacher Resourcecovered with ice. As sea ice decreases, the amount
149 of habitat available to these predator
Pre-AP Biology TEACH
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species increases, and can cause significant changes in trophic cascades.

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.11: Predicting Changes in Arctic Ecological Communities

UNIT 1 PART 2: MAKING PREDICTIONS AND ASKING SCIENTIFIC QUESTIONS

In this part of this lesson, students begin with a brief reading about the relationship
between sea ice and some predator species in the Arctic food web. Then they practice
making predictions and asking questions using information about Arctic species and
ecosystems.

ƒ To begin, have students pair up and read the initial text about the importance
of Arctic sea ice in Part 2 of Handout 1.11.A: Predicting Changes in Arctic
Ecological Communities.
ƒ Once students have completed the reading, provide each pair with a set of the
cards from Handout 1.11.B: Arctic Species Information Cards. Students should
organize the cards in such a way that it will be easy for them to quickly find
information about different species.
ƒ For the upcoming portion of this lesson, students need to understand the
information and vocabulary (e.g., ice-obligate, ice-associated, and seasonally
migrant) used on the cards. To build this understanding, give students time to
arrange the cards, and then randomly call on different students to answer some
preliminary questions, such as the following:
u What term can we use to describe the relationship between a bearded seal and
ice? (If they don’t understand the question, ask if bearded seals are ice-obligate,
ice-associated, or seasonally migrant species.)
Bearded seals are ice-obligate.
u What would happen to the bearded seal population if the area of sea ice
decreased?
Their populations would likely decrease if the area of sea ice decreased.
u What term can we use to describe the relationship between a humpback whale
and ice?
Humpback whales are seasonally migrant.
u What would happen to the humpback whale population if the area of sea ice
decreased?
Their populations would likely increase if the area of sea ice decreased.
ƒ Now that students have familiarized themselves with the cards, have student pairs
work together to complete both the Species Predictions Table and the Asking
Scientific Questions question set. The question set requires students to apply and
build on some of the predictions they have made.

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 Key Concept ECO 5: Changes in Ecological Communities

LessonLesson
1.11: Predicting Changes
1.11: Predicting ChangesininArctic Ecological
Arctic Ecological Communities
Communities

Unit 1: Ecological Systems

ƒ As pairs are working, circulate around the room and provide support as needed. UNIT 1
SPECIES PREDICTIONS
Sample responses TABLE
to the table and question set are provided here for your use in HANDOUT
1.11.A
supporting
Your students.
teacher will However,
give you allowapairs
and a partner set ofto workSpecies
Arctic through the table and
Informational questions
Cards.
without
Read eachstopping to check
card and work answers
together as a class.
to organize themStudents willcan
so that you share responses
refer as a
back to them
towhole
quickly get information. After you have organized
class in the final part of this lesson. your cards, use the information on
them to complete the table and questions about environmental change.

Species Sea Ice Change in Predicted Effect and Reasoning

Requirement Sea Ice
Walrus Ice-obligate Decrease Walrus populations will likely decline if the
area of sea ice decreases, due to the loss of
critical habitat.

Gray Whale Seasonally Decrease Gray whale populations will likely increase
migrant if the area of sea ice decreases, due to the
opening of new feeding grounds.

Ringed Seal Ice-obligate Increase Ringed seal populations will likely increase
if the area of sea ice increases, due to the
availability of additional habitat.

Narwhal Ice-associated No change Narwhal populations are likely to not be

affected if there is no change in the area of
sea ice in the Arctic.

Killer Seasonally Decrease Killer whale populations will likely increase

Whale migrant if the area of sea ice decreases, due to the
opening of new feeding grounds.

Polar Bear Ice-obligate Increase Polar bear populations will likely increase
if the area of sea ice increases, due to the
availability of additional habitat.

Polar Bear Ice-obligate Decrease Polar bear populations will likely decline if
the area of sea ice decreases, due to the loss
of critical habitat.

Spotted Seal Ice-associated Decrease Spotted seal populations will likely decline if
the area of sea ice decreases, due to the loss
of habitat.

Handout 1.11.A

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 Key Concept ECO 5: Changes in Ecological Communities
Lesson
Lesson 1.11:
1.11: PredictingChanges
Predicting Changes ininArctic
ArcticEcological Communities
Ecological Communities
Unit 1: Ecological Systems

UNIT 1
HANDOUT ASKING SCIENTIFIC QUESTIONS
1.11.A

1. Based on the change in sea ice area since 1980, make three predictions about how
the sea ice change has affected specific Arctic species.
Answers will vary but should include information similar to those in the table
students previously completed. For example, “Ringed seal populations are likely
to have declined since 1980 due to the decrease in sea ice extent.”

2. Use data from the graph in Part 1 to predict the year in which ice-obligate species
were impacted the most?
Sample response: In 2012, Arctic sea ice extent was at its lowest and therefore
ice-obligate species would have been greatly impacted that year.

3. State a scientific question, based on one of your predictions.

This is a critical component of the lesson. A related scientific question might read
like one of the following: “Are ringed seal populations declining as a result of the
decrease in the area of sea ice?” or “Will killer whale populations increase due to the
decrease in Arctic sea ice?”
4. Identify the data that scientists would need to collect to answer your scientific
question.
Sample response: The population of ringed seals (or killer whales) over time, and
the area of sea ice over time.

5. What methods could scientists use to collect the data required to answer your
scientific question? Be specific.
Sample response: They could use population biology methods to determine the
number of ringed seals: mark−recapture, quadrat sampling, aerial photography,
feeding signs, vocalization, or visual observation of breathing. They could use
satellite data to measure sea ice extent.
6. Think about the city or state in which you live. If the area of your city or state
was substantially decreased, predict what would happen to you and your fellow
residents.
Student answers will vary but should include some thinking about how the loss of
habitat and/or resources could impact their local ecological community.

Handout 1.11.A
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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.11: Predicting Changes in Arctic Ecological Communities

PART 3: SUMMARY UNIT 1

In the final part of this lesson, students share some of their predictions and scientific
research questions from Part 2 in a whole-class discussion. Students are also prompted
to reflect on and discuss their own role in the local ecosystem.

ƒ Lead a whole-class discussion in which student pairs share their predictions

about the scenarios in the Species Predictions Table. Then, ask pairs to share their
suggested scientific questions (question 3). Record student ideas for the whole class
to see.
ƒ To prompt further discussion, consider asking these follow-up questions:
u When looking at your table, what organisms will suffer most if sea ice extent
continues to decline by approximately 12% each decade?
u In what ways could we easily modify some of our daily activities to decrease our
contribution of carbon dioxide to the atmosphere?

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 Key Concept ECO 5: Changes in Ecological Communities

UNIT 1 LESSON 1.12

Understanding Beavers as Ecosystem Engineers

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Part 1: Close Reading ƒ Emphasis on Analytical
Students read a science text about the role of Reading and Writing
beavers as ecosystem engineers and practice close
reading strategies to extract information and
SUGGESTED TIMING
evidence from this text.
~60 minutes
Part 2: Writing to Think About the Text
Students use writing strategies, such as working HANDOUT
with sentence frames and outlining, to organize
ƒ 1.12: Understanding
and refine their thoughts and evaluate the reading.
Beavers as Ecosystem
Engineers
CONTENT FOCUS
This lesson requires students to apply analytical
reading and writing skills to an extended science text, and builds on key ideas from
prior lessons: food webs, an organism’s role in the ecosystem, and biological responses
to changes in the ecosystem. Students apply and transfer knowledge of these ideas to a
novel situation (i.e., the beaver as an ecosystem engineer). This lesson also serves as a
primer for subsequent instruction on community changes over time (e.g., primary and
secondary succession events).

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.12: Understanding Beavers as Ecosystem Engineers

COURSE FRAMEWORK CONNECTIONS UNIT 1

Enduring Understandings

ƒ The dependence on the availability of abiotic and biotic resources results in

complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

Learning Objectives Essential Knowledge

ECO 5.1(a) Explain how natural changes ECO 5.1.1 Ecosystem biodiversity is
in the ecosystem affect ecosystem influenced by several naturally occurring
dynamics. factors that alter the environment.
ECO 5.1(c) Analyze data to make d. Keystone species and ecosystem
predictions about the effects engineers (e.g., elephants, beavers)
on biodiversity in response to dramatically affect biodiversity in the
environmental changes. ecosystem.

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.12: Understanding Beavers as Ecosystem Engineers

UNIT 1 PART 1: CLOSE READING

In the first part of the lesson, students read an extended science text about the role of
beavers as ecosystem engineers (Handout 1.12: Understanding Beavers as Ecosystem
Engineers) and practice close reading strategies to extract information and evidence
from this text.

ƒ To begin, read the text aloud, pausing at key moments to gather student feedback
about important ideas from it. Some guiding
prompts for class discussion could include:
Classroom Ideas
u What does the term engineer mean? (after
As this is a longer text,
paragraph 2) you may want to use a
u Why are humans and beavers compared with jigsaw arrangement for
one another? the independent reading
task. Arrange students
u How are humans and beavers similar and
in groups and have each
different, according to the text? group member closely
u What activities of the beaver support the read a different portion
common expression “eager beaver”? (after of the text; then, each
paragraph 3) group member shares
their notes about the
u Why do you think MIT adopted the beaver as reading with the group.
the university mascot?
u What characteristics of the beaver surprised you?
(after paragraph 5)
ƒ Students should reread the text independently
Meeting Learners’ Needs
and practice close reading strategies, such as
This is an extended reading
highlighting and summarizing. Students should that requires students
also identify key terms and concepts and examine to extract important
the figures in the text. information from the text.
It is critical that students
PART 2: WRITING TO THINK ABOUT THE TEXT practice these analytical
reading skills; however,
In this part of the lesson students use writing strategies,
it may be beneficial for
such as sentence frames and outlines, to help organize students who need extra
and refine their thoughts and evaluate the reading. support to only read 2–3
These strategies help students craft more coherent paragraphs at a time.
evidence-based written claims. Then regroup to discuss
key ideas and challenging
ƒ Instruct students to fill in the sentence frames words as a class.
in the handout to help them articulate the key

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 Key Concept ECO 5: Changes in Ecological Communities

Lesson 1.12: Understanding Beavers as Ecosystem Engineers

concepts from the text. As students are working, circulate through the classroom UNIT 1
and provide guidance as needed. Some sample responses to the sentence frames are
shown below.
u The formation of dams happens as a result of beavers gnawing down trees and
stacking them in rivers or creeks.
u I know that beavers are adapted to swimming because they have webbed feet and
strong hind legs.
u I predict that the ecosystem in a river would change if beaver dam construction
occurs.
ƒ After students have completed their sentence frames, have them form groups of
three or four to share the key concepts they have articulated. Encourage students
to engage in peer-to-peer discussion about these concepts, challenging each other’s
statements and asking for clarification as appropriate. As needed, monitor and
guide these conversations to model effective peer-to-peer discussion.
ƒ Once students have discussed the concepts in their small groups, lead a whole-
class discussion to summarize the key concepts students identified. Some guiding
prompts for class discussion could include:
u What words in this reading were new to you?
u What ecological role do you think the beaver plays?
u What evidence from the text signals the beaver’s ecological role?
u What images come to mind now when you think of a beaver dam?
ƒ Next, students should work individually to collect evidence from the text,
supporting or refuting the following prompts from the handout:
u Claim 1: Both humans and beavers are skilled ecosystem engineers.
u Claim 2: Beavers are not well adapted to living in aquatic ecosystems.
Guide students to record their responses in the paragraph outline structure
provided on the handout.
ƒ After students have had time to record their evidence individually, have them
discuss and share their responses. Try to elicit responses from students who
developed opposing arguments or who used different pieces of evidence.
ƒ To complete the lesson, ask students to work individually to write out or sketch
a hypothetical food web for the beaver pond on Red River. As indicated on the
handout, students should then write a prediction of how this food web might
change once the beaver dam is gone (breached) and the ecosystem returns to a
river.

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 Unit 1

Performance Task

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

PERFORMANCE TASK UNIT 1

Exploring Species Interactions in

the Great Barrier Reef
AREAS OF FOCUS
OVERVIEW
ƒ Emphasis on Analytical
Reading and Writing
DESCRIPTION
ƒ Attention to Modeling
This performance task engages students in all the ƒ Strategic Use of
areas of focus. They use their analytical reading Mathematics
skills to extract important information from a
dive in order to journal to develop a model of a
SUGGESTED TIMING
coral reef ecosystem and describe community
~30–45 minutes
interactions. They also use mathematics to
describe population density of the coral.
HANDOUT
Unit 1 Performance
CONTENT FOCUS
Task: Exploring Species
This performance task assesses student understanding
Interactions in the Great
across many of the key concepts from this unit.
Barrier Reef
Students demonstrate their knowledge of energy
transfer and aquatic community dynamics as they
MATERIALS
create a model of a coral reef food web and use
data to describe the coral population density. They ƒ calculator (optional)
also demonstrate their understanding of symbiotic
relationships and make predictions about what can
happen to coral reef ecosystems when human-induced
changes occur.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Most ecosystems rely on the conversion of solar energy into chemical energy for
use in biological processes.
ƒ The dependence on the availability of abiotic and biotic resources results in
complex and dynamic interactions between organisms and populations.
ƒ Changes to the environment can alter interactions between organisms.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1 Learning Objectives Essential Knowledge

ECO 2.2(a) Use data to explain the ECO 2.2.1 Population growth patterns
growth of a population. are influenced by the availability of
resources and the interactions that occur
within and between populations of
species.
b. Both density-dependent (e.g.,
nutrients and food) and density-
independent (e.g., weather, natural
disasters) factors regulate population
growth.

ECO 2.3(a) Create and/or use models to ECO 2.3.1 Energy availability helps
explain the transfer of energy through shape ecological communities.
the food web of a community. a. Typically, only 10 percent of the total
energy in a given trophic level is available
to organisms in the next higher trophic
level.
b. The metabolic activity required to
utilize the energy available in any given
trophic level results in a loss of thermal
energy to the environment, as heat.
c. The energy available to organisms
decreases from lower-order trophic levels
(primary producers) to higher-order
trophic levels (tertiary consumers).

ECO 3.2(a) Describe differences in the ECO 3.2.2 Aquatic biomes can generally
abiotic and/or biotic factors that shape be classified according to their salt
aquatic and terrestrial communities. concentrations: oceanic, brackish, and
freshwater.
a. Two major abiotic factors that help
define terrestrial biomes are climate
(temperature, precipitation) and soil
type.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1
ECO 4.2(a) Describe what symbiotic ECO 4.2.1 Competition in ecosystems
relationship exists between two has led to symbiotic relationships where
organisms. two or more species live closely together.
ECO 4.2(b) Explain how a symbiotic a. Mutualistic relationships often form
relationship provides an advantage for to provide food or protection for both of
an organism by reducing one or more the organisms involved.
environmental pressures. b. Parasitic relationships benefit only
one organism in the relationship (the
symbiont) and harm the host.
c. Commensalism is a kind of
relationship that benefits only one
organism in the relationship (the
symbiont); the host is neither harmed
nor helped.

ECO 5.1(a) Explain how natural changes ECO 5.1.1 Ecosystem biodiversity is
in the ecosystem affect ecosystem influenced by several naturally occurring
dynamics. factors that alter the environment.
ECO 5.1(b) Create and/or use models to a. Changes in energy, nutrient, and niche
make predictions about how changes in availability influence an ecosystem’s
biodiversity affect local ecosystems. biodiversity.

ECO 5.2(b) Given a human activity, ECO 5.2.1 Human activities (e.g.,
predict the potential biological urbanization, farming, tree harvesting)
consequences for an ecosystem’s also alter availability of nutrients, food,
biodiversity. and niches for species and therefore
affect population and community
dynamics.
a. Human activities include
anthropogenic climate change, the
introduction of invasive species, habitat
destruction, and air/water pollution.
b. The effects of human-induced
environmental changes and their impact
on species are the subject of a significant
amount of current scientific research.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1 Exploring Species Interactions

in the Great Barrier Reef

SCORING GUIDELINES
There are 17 points possible for this performance task.

Question 1(a)

Sample Solutions Points Possible

Lemon Barracuda 3 points maximum

Shark
1 point: All arrows point in
the direction of the flow of
Nurse energy
Loggerhead Parrotfish
Shark
2 points: Sketch includes
at least four accurate
Cleaner relationships. Two or three
Conch Coral
Wrasse should earn 1 point.
Scoring note: Some students
Algae may choose to include the
fungus on the food web,
which is absolutely fine but
not necessary to earn all
the points on this question.
Targeted Feedback for Student Responses

Since students must extract information directly from the dive journal texts, they may fail
to include all the organisms in their model. Encourage them to go back to the dive journals,
underline each mention of an organism, and ensure they are placed appropriately in the food
web model.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Question 1(b) UNIT 1

Sample Solutions Points Possible

Lemon Barracuda 1 point maximum

Shark
1 point for labeling at
Secondary
Consumers Nurse
least one organism with
Loggerhead Parrotfish
Shark the correct ecological role
for each of the three roles
Primary
Consumers Conch Cleaner Coral asked for (e.g., primary
Wrasse
producers)
Primary
Producers Algae

Targeted Feedback for Student Responses

If students struggle to find appropriate pairings for these ecological roles, have them return to
the dive journal to find evidence of how the organism is acquiring energy, so they can provide
an appropriate label (e.g., since cleaner wrasse eat algae, which is a primary producer, they
should be labeled as primary consumers).

TEACHER NOTES AND REFLECTIONS

Question 1(c)

Sample Solutions Points Possible

Lemon Barracuda 1 point maximum

Shark
1 point for labeling at
Secondary
Consumers Nurse
least one organism with
Loggerhead Parrotfish
(Omnivores and Shark the correct ecological role
Carnivores)
for each of the three roles
Primary
Consumers Conch Cleaner Coral asked for (e.g., autotrophs)
(Herbivores) Wrasse

Primary
Producers Algae
(Autotrophs)

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1 Targeted Feedback for Student Responses

If students struggle to find appropriate pairings for these ecological roles, have them return to
the dive journal to find evidence of how the organism is acquiring energy, in order to provide
an appropriate label (e.g., since the algae acquire energy from sunlight, they should be labeled
as autotrophs).

TEACHER NOTES AND REFLECTIONS

Question 2(a)

Sample Solutions Points Possible

Area = Length × width 1 point maximum

1 point for correctly calculating surface
2m 2m 2m
area
Quadrat Quadrat Quadrat
2m
1 2 3

Sample Plot = 6 m × 2 m =12 m 2

Targeted Feedback for Student Responses

Some students may struggle in setting up their calculations. Encourage them to use the
diagram of the quadrats and label the total length and width (as shown in the student
sample).

TEACHER NOTES AND REFLECTIONS

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Question 2(b) UNIT 1

Sample Solutions Points Possible

4 x 1 point maximum
=
12 m 120 m 2
2
1 point for correctly calculating
480 m 2 = (12 m 2 ) x expected population size
Scoring notes:
480 m 2
=x ƒ Some students may see that the area
12 m 2
40 = x given, 120 m 2, is 10 times larger
than the original experimental
plot. So, they may jump to simply
multiplying 10 by the original
population to get 40. This strategy
demonstrates the use of structure in
numbers and should also receive full
credit.
ƒ If students use an incorrect value
for surface area, due to errors in
part (a), but do the calculations in
part (b) correctly, they should be
awarded full credit for part (b).
Targeted Feedback for Student Responses

If students have an incorrect setup, provide them with a partially developed setup and
have them return to the data to complete it. For example, you could provide:
# of coral on dive 1 x
×
area of all 3 quadrats (m ) total reef area (m 2 )
2

TEACHER NOTES AND REFLECTIONS

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1 Question 2(c)

Sample Solutions Points Possible

Students could identify any of the following 1 point maximum

species: lemon shark, barracuda, parrotfish, 1 point for listing at least two correct
nurse shark, loggerhead. Mark and recapture species and providing an appropriate
is a useful sampling method for mobile explanation
animals.
Targeted Feedback for Student Responses

If students do not recall why mark−recapture would be more appropriate for moving
organisms, have them return to Lesson 1.6 and review the data collection methods.

TEACHER NOTES AND REFLECTIONS

Question 2(d)

Sample Solutions Points Possible

Since coral are sessile (do not move), the 1 point maximum
mark−recapture method would not be 1 point for providing an appropriate
appropriate. Quadrat sampling is best for explanation
organisms with limited mobility.
Targeted Feedback for Student Responses

If students do not recall why the quadrat method would be more appropriate for
nonmobile organisms, have them review the quadrat data collection methods used in
Lesson 1.6.

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UNIT 1
TEACHER NOTES AND REFLECTIONS

Question 3

Sample Solutions Points Possible

Type of Example(s) Reasoning

4 points maximum
Interaction Award 0.5 points for each correct
Zooxanthellae It’s a benefit to both since example of a type of species
algae and zooxanthellae provide coral interaction
coral with nutrients and they Award 0.5 points for each correct
receive protection from reasoning that is paired with a type of
predation. species interaction
Mutualism
Cleaner The cleaner wrasses get
wrasse and nutrients from the algae and
turtle the turtle benefits from the
removal of the algae from its
shell.
Parasitism Cleaner The fungus benefits by
wrasse and feeding on the cleaner
fungus wrasse. The cleaner wrasse
is harmed by the fungus.
Interspecific Barracuda They are two different
Competition and lemon species, both after the same
shark prey (parrotfish).

Several were competing for

Parrotfish
the algae on the coral.

Many were competing for

Intraspecific Cleaner
algae found on the turtle’s
Competition wrasse
shell.

Two were competing for

Nurse sharks
coral.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

UNIT 1 Targeted Feedback for Student Responses

If students do not find appropriate pairings for each type of interaction, have them
return to the text of the dive journal and underline each relationship they find between
organisms.

TEACHER NOTES AND REFLECTIONS

Question 4(a)

Sample Solutions Points Possible

Primary consumers such as the conchs and 2 points maximum

parrotfish would decline due to lack of their 1 point for each correct prediction
food source; secondary consumers such based on an appropriate ecological
as loggerhead turtles would decline since relationship
their food sources, such as conchs, are also
declining.
Targeted Feedback for Student Responses

If students do not make reasonable predictions, encourage them to return to their

model and add arrows to show what would happen to each organism in the food web if
the coral was to decline.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Question 4(b) UNIT 1

Sample Solutions Points Possible

Algae are primary producers. Therefore, 2 points maximum

their decline can cause a decline in both 1 point for the ecological role of the
primary consumers who depend on them algae
directly as a food source and secondary
1 point for food web importance
consumers who depend on the primary
consumers.
Targeted Feedback for Student Responses

If students struggle with appropriate answers, have them return to their labeled models
in order to analyze the ecological role algae play and the impact it would have on the
reef as a system if they were to decline.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Unit 1: Ecological Systems

PERFORMANCE
TASK
Exploring Species Interactions in the Great
Barrier Reef
To say that the Great Barrier Reef is the world’s largest coral reef
may be understating things; the Australian government notes that
it is “the only living organic collective visible from Earth’s orbit.”
Certainly, it is vast—a conglomeration of some 3,000 reefs and
600 islands stretching more than 1,250 miles along Australia’s
northeast coast. Sea turtles, dolphins and whales live there, along
with 200 species of birds, 1,500 species of fish, 4,000 species of
mollusks and, yes, an abundance of corals.
Excerpt from T.A. Frail, “Diving Into the Great Barrier Reef.” © 2008 Smithsonian
Institution. Reprinted with permission from Smithsonian Enterprises. All rights
reserved. Reproduction in any medium is strictly prohibited without permission
from Smithsonian magazine. https://www.smithsonianmag.com/travel/diving-
into-the-great-barrier-reef-11923941.

In 2008, a marine biologist and her research team were interested in the complex
relationships that exist among the many organisms found within the Great Barrier
Reef. They made several dives over the course of a few months and recorded their
observations. Below are journal entries from two of their dives:

Dive 1 Journal (January 21, 2008): This area of the reef seems to have a healthy
population of algae growing on and in the coral which supports a diverse reef
ecosystem. There is a healthy diversity of vibrant colors of the coral species due
to the presence of zooxanthellae algae that live in the tissue of the coral polyps.
These algae provide not only color to the coral but also energy, while safely
protected in the tissue of the coral. There were four nurse sharks present on this
dive. Two of them were actively feeding on the coral, alongside several parrotfish
eating algae growing on the coral.

Dive 2 Journal (March 11, 2008): Today we recorded one female loggerhead
turtle on the reef. She successfully preyed upon a large conch mollusk that was
grazing on the algae on the coral. She was surrounded by dozens of small cleaner
wrasse fish that were feeding on the algae covering her shell. We also noticed that
one of the cleaner wrasses appears to have a puffy white fungus that is feeding on
its dorsal fin tissue. We encountered one large barracuda and a lemon shark, both
chasing a juvenile parrotfish.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Unit 1: Ecological Systems

1. Based on the marine biologist’s research journal entries: PERFORMANCE

TASK
(a) Sketch a food web for the portion of the Great Barrier Reef that was being
observed.
(b) Label the primary producer(s), primary consumer(s), and secondary
consumer(s) in your food web.
(c) Label one autotroph, one herbivore, and one carnivore in your food web.

2. The research team also conducted a population study on brain coral during their
dives. They used three quadrats in a line (transect). Each quadrat measured
2 m × 2 m.

Quadrat Quadrat Quadrat

1 2 3

After each dive, they recorded the total number of brain coral for all three
quadrats:

Dive Total Number

of Brain Coral

1 4

2 3

(a) Calculate the total surface area (m 2 ) of the entire sampling plot (all three
quadrats). Show your work.

(b) If researchers use only the number of coral found in dive 1, calculate the
predicted population of brain coral in a reef that covers 120 m 2. Show your
work.

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Unit 1: Ecological Systems

PERFORMANCE (c) Identify two organisms in the food web you sketched (see question 1) that
TASK
you could sample using the mark−recapture method. Explain why the mark−
recapture method is appropriate for the organisms you identified.

(d) Explain why the researcher chose to use the quadrat method rather than
mark and recapture to sample the coral population.

3. Based on the marine biologist’s observations, find one example of each type of
species interaction listed in the table below. For each example, also include your
reasoning as to why it illustrates this type of interaction (see example provided).

Type of Example(s) Reasoning

Interaction

Zooxanthellae algae and It’s a benefit to both since

coral zooxanthellae provide coral
with nutrients and coral
receive protection from
Mutualism predation.

Parasitism

Interspecific
Competition

Intraspecific
Competition

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 Performance Task: Exploring Species Interactions in the Great Barrier Reef

Unit 1: Ecological Systems

4. In 2018, the marine biologist’s team returned to the Great Barrier Reef. They PERFORMANCE
TASK
noticed sizable areas of coral bleaching due to reductions of the symbiotic
photosynthetic algae population. They are concerned that warming ocean
temperatures may be causing a decline of important algae populations.
(a) If algae populations continue to decline, predict how this might impact the
Great Barrier Reef food web.

(b) Describe why the algae population is so vital to this ecosystem.

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 Unit 2

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 Unit 2
Evolution

Overview
SUGGESTED TIMING: APPROXIMATELY 4 WEEKS

In this unit, students explore the diverse types of data and multiple lines of evidence
that have informed our understanding of the theory of evolution over time. Students
should have a general familiarity with concepts associated with evolution from middle
school life science. This course is designed to build on that general understanding
to provide a foundation in the mechanisms of evolution. This includes both small-
scale evolution (changes in the relative frequency of a gene in a population from
one generation to the next) and large-scale evolution (speciation events over many
generations).

ENDURING UNDERSTANDINGS
This unit focuses on the following enduring understandings:
The theory of evolution states that all organisms descend from a common ancestor
and share some characteristics.
Biological evolution is observable as phenotypic changes in a population over
multiple successive generations.
Speciation, extinction, and the abundance and distribution of organisms occur in
response to environmental conditions.

KEY CONCEPTS
This unit addresses the following key concepts:

EVO 1: Patterns of Evolution

EVO 2: Mechanisms of Evolution
ƒ EVO 3: Speciation

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 Overview

UNIT 2 UNIT RESOURCES

The tables below outline the resources provided by Pre-AP for this unit.

Lessons for Key Concept EVO 1: Patterns of Evolution

Lesson Title Learning Essential Suggested Areas of Focus

Objectives Knowledge Timing
Addressed Addressed

2.1: Launch EVO 1.1(a), EVO 1.1.2a, ~45 minutes Attention to

Lesson – EVO 1.1(b) EVO 1.1.2b Modeling
Examining
Evidence of
Evolution

2.2: Examining EVO 1.1(a) EVO 1.1.2a ~60 minutes Emphasis on

Anatomical Analytical
Evidence from Reading and
Fossils – Writing
Spinosaurus
The following Key Concept EVO 1 learning objectives and essential
knowledge statements are not addressed in Pre-AP lessons. Address
these in teacher-developed materials.

ƒ Learning Objectives: EVO 1.2(a), EVO 1.2(b)

ƒ Essential Knowledge Statements: EVO 1.1.1, 1–2 for EVO
1.1.2b, EVO 1.2.1a, EVO 1.2.1b

Lessons for Key Concept EVO 2: Mechanisms of Evolution

Lesson Title Learning Essential Suggested Areas of

Objectives Knowledge Timing Focus
Addressed Addressed

2.3: Launch EVO 2.2(a) EVO 2.2.1a Less than 45 Emphasis on

Lesson – minutes Analytical
Variation Reading and
in Asian Writing
Ladybugs

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 Overview

UNIT 2
2.4: Modeling EVO 2.2(a), EVO 2.2.1a, ~180 minutes Attention to
Natural EVO 2.2(b), EVO 2.2.1b, Modeling
Selection Lab EVO 2.2(c), EVO 2.2.1c,
EVO 2.2(d) EVO 2.2.1d,
EVO 2.2.1e,
EVO 2.2.2a
The following Key Concept EVO 2 learning objectives and essential
knowledge statements are not addressed in Pre-AP lessons. Address
them in teacher-developed materials.

ƒ Learning Objectives: EVO 2.1(a)

ƒ Essential Knowledge Statements: EVO 2.1.1a, EVO 2.1.1b

Practice Performance Task for Unit 2 (~45 minutes)

This practice performance task draws on learning objectives and essential knowledge
statements addressed throughout Key Concept EVO 2: Mechanisms of Evolution.

Learning Checkpoint 1: Key Concepts EVO 1 and EVO 2 (~45 minutes)

This learning checkpoint assesses learning objectives and essential knowledge

statements from Key Concepts EVO 1 and EVO 2. For sample items and learning
checkpoint details, visit Pre-AP Classroom.

Lessons for Key Concept EVO 3: Speciation

Lesson Title Learning Essential Suggested Areas of

Objectives Knowledge Timing Focus
Addressed Addressed

2.5: Launch EVO 3.1(a), EVO 3.1.1a, ~45 minutes Emphasis on

Lesson – EVO 3.1(b) EVO 3.1.1b, Analytical
Introduction EVO 3.1.1c, Reading and
to the Process EVO 3.1.1d Writing
of Speciation—
Salamander
Evolution

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 Overview

UNIT 2 The following Key Concept EVO 3 learning objectives and essential
knowledge statements are not addressed in Pre-AP lessons. Address
these in teacher-developed materials.

ƒ Learning Objectives: EVO 3.2(a), EVO 3.2(b), EVO 3.2(c)

ƒ Essential Knowledge Statements: EVO 3.2.1a, EVO 3.2.1b,
EVO 3.2.1c, EVO 3.2.1d

Learning Checkpoint 2: Key Concept EVO 3 (~45 minutes)

This learning checkpoint assesses learning objectives and essential knowledge

statements from Key Concept EVO 3. For sample items and learning checkpoint
details, visit Pre-AP Classroom.

Performance Task for Unit 2 (~45 minutes)

This performance task assesses learning objectives and essential knowledge statements
from the entire unit.

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 Key Concept EVO 1: Patterns of Evolution

LESSON 2.1 UNIT 2

Launch Lesson – Examining Evidence of Evolution

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Part 1: Examining Archaeopteryx ƒ Attention to Modeling
The first part of the launch lesson has students
closely observe a picture of Archaeopteryx.
SUGGESTED TIMING
Together the class generates a list of
~45 minutes
Archaeopteryx’s observable characteristics and
inferences about the roles of those characteristics.
HANDOUT
Part 2: Evolution of Birds
ƒ 2.1: Examining
Students first examine a variety of sources about
Evidence of Evolution
fossil evidence for the evolution of birds from
theropods. Then, they examine data, based on
MATERIALS
fossil record evidence, to draw conclusions about
how Archaeopteryx serves as an intermediate link ƒ LCD projector,
between dinosaurs and birds. electronic whiteboard,
or other technology for
showing students a
CONTENT FOCUS
detailed image and an
This lesson is an introduction to the idea of examining
online video
anatomical features of fossils to establish lines of
ƒ internet access to the
evidence for evolutionary relationships. It also
National Geographic
introduces students to how scientists model these
video “The Feathered
relationships using tools such as phylogenetic trees.
Dinosaur” (3:39),
available at https://
www.youtube.com/
watch?v=LQcoLWJmsp0

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.1: Launch Lesson – Examining Evidence of Evolution

UNIT 2 COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ The theory of evolution states that all organisms descend from a common
ancestor and share some characteristics.
ƒ Biological evolution is observable as phenotypic changes in a population over
multiple successive generations.

Learning Objectives Essential Knowledge

EVO 1.1(a) Use scientific evidence EVO 1.1.2 Scientists use various sources
to justify a claim of an evolutionary of evidence to establish evolutionary
relationship between species. relationships between organisms.
EVO 1.1(b) Describe shared a. Fossil evidence, in conjunction with
characteristics (homologies) among relative and radiometric dating, provides
organisms that provide evidence for insight into the geographic and temporal
common ancestry. distribution of species throughout Earth’s
history.
b. Comparisons of anatomical and
molecular homologies are used to
determine the degree of divergence from
a common ancestor.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.1: Launch Lesson – Examining Evidence of Evolution

PART 1: EXAMINING ARCHAEOPTERYX UNIT 2

In the first part of the launch lesson, students get a sense of how scientists engage with
fossil evidence to develop and refine claims about the evolution of organisms over
time from a common ancestor. Students focus on anatomical features of a fossil of
Archaeopteryx to gain insight into the organism’s characteristics and possible ecological
role. The discovery of Archaeopteryx in the 1860s was important in paleontologists’
understanding of the evolution of birds as it was the first dinosaur fossil found with
feathers.
To begin, have students closely observe a detailed image of an Archaeopteryx
lithographica fossil such as the one shown. Students should be able to see details
such as wing and tail feather imprints, ribs, teeth, claws, and distinct digits. You
could display the image using an LCD projector or electronic whiteboard or have
students view it on individual devices.

Archaeopteryx lithographica (45 cm fossil size = ~1.5 ft). Credit: James L. Amos,
National Geographic Society. CC BY 1.0. https://commons.wikimedia.org/wiki/File:
Archaeopteryx_fossil.jpg.

ƒ As students examine the image, have them record any observations about
Archaeopteryx’s anatomy. Next, have them use those observations to draw some
inferences about this organism’s characteristics and behaviors. It will be helpful to
generate a list of student responses on the board for the class to see.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.1: Launch Lesson – Examining Evidence of Evolution

UNIT 2
Instructional Rationale

The purpose of this part of the lesson is for students to take their time to make
observations about the fossil, as scientists would do, before they consider any
inferences.

Some possible student answers may include:

Anatomical Inferences
Characteristics

Feathers Archaeopteryx may have been able to fly and likely was a
terrestrial organism.
Feathers may have provided insulation, coloration for
mating, or camouflage.

Claws on wing Claws may have been used for protection and/or
predation.

Backbone that extends Backbone allowed for greater range of movement and
into tailbone protection of spinal cord.

Feet bones (phalanges) Archaeopteryx could walk, run, and climb.

have 3 distinct digits

Rib cage The rib cage provided protection for internal organs.

Teeth Archaeopteryx possibly was a carnivorous predator.

PART 2: EVOLUTION OF BIRDS

Classroom Ideas
To begin the second part of the lesson, students explore If you have time, you could
additional discoveries involving feathered dinosaurs also show students a video
that have fueled our understanding of dinosaurs and on the importance of the
the evolution that led to birds. This part of the lesson is discovery of Archaeopteryx:
intended to help students gain an appreciation for how “Great Transitions: The
Origin of Birds” (https://
new scientific evidence that emerges from discovering
www.biointeractive.org/
new fossils continues to strengthen our understanding
classroom-resources/
of evolutionary processes. great-transitions-
origin-birds).

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.1: Launch Lesson – Examining Evidence of Evolution

ƒ First, remind students that Archaeopteryx was an important discovery in our UNIT 2
understanding of the evolution of birds, since it was the first dinosaur fossil
found with feathers. Then, show the National Geographic video, “The Feathered
Dinosaur” (https://www.youtube.com/watch?v=LQcoLWJmsp0), about the 1996
discovery of Sinosauropteryx.
ƒ Next, have students read the excerpt from a Nature article on feather color in
dinosaurs (see “Fossil Feather Colors” on Handout 2.1: Examining Evidence for
Evolution).
ƒ Once students have completed the reading, ask them to draft one or two sentences
summarizing the article. Invite volunteers to share their sentences with the class.
From the article, students should be aware that scientists found color-producing
organelles in fossil dinosaur feathers. These organelles have also been found in
fossilized bird feathers and are present in modern-day animals.

Now that students have a better understanding of how scientists use fossil evidence to
support their claims about the characteristics of species over time, they will use two
figures provided on the handout to support the inferences they made in Part 1 of this
lesson about Archaeopteryx. The first figure shows stratigraphic ranges and origins of
some major animal groups to help students gain a better sense of the scale of time and
to place the evolution of birds in relationship to the evolution of other organisms. The
second figure, called an evogram, includes a phylogenetic tree combined with species
timeline information.

ƒ To first orient students to the two figures on their handout, you may want to pose
the following questions:
u Why do you think some organisms become fossils and others do not?
u According to the first figure, how many millions of years before birds are found in
the fossil record is there evidence of the presence of reptiles?
u What do the branches on the phylogenetic tree in the second figure represent?
u What type of evidence would cause scientists to create a new branch on the
phylogenetic tree?

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.1: Launch Lesson – Examining Evidence of Evolution

UNIT 2
Guiding Student Thinking

Students often struggle with understanding why relatively few organisms are fossilized
in Earth’s rock layers. They tend to think that fewer fossils points to weaknesses in
evolutionary theory since they don’t fully appreciate how rare the events are that result
in fossilization of organisms. You can remind students that in order to be fossilized,
organisms must be covered quickly by sediments, such as gravel, mud, or sand (or
sometimes volcanic ash). Emphasize that this typically occurs only if organisms die or
are involved in events near lakes, rivers, or oceans where they can be quickly covered
by sediments, which preserves skeletal structures. Over time, the layers of sediments
are compacted by the weight of overlying sediments and cemented together to
become the sedimentary rocks called limestone, shale, sandstone, and conglomerate.
The buried plant and animal remains become fossils within the sedimentary layers
and are only discovered as these layers erode away or are purposefully excavated by
paleontologists.

ƒ Once students have analyzed the two figures,

Meeting Learners’ Needs
have them work in pairs to use the phylogeny to
If students need support
determine in which group(s) each of the
in how to craft statements
characteristics listed in the data table on the of evidence to defend a
handout occur. Then students should identify the scientific claim, you may
evidence that supports their conclusions. Sample want to have them work
responses are shown on the next page. with a partner and write
down their evidence prior
ƒ Finally, lead a whole-class discussion on the
to engaging in a whole-
following prompts: class discussion. Having
u What characteristics of dinosaurs do modern students write before
birds still exhibit? they discuss will give
them time to reflect more
u Defend the following scientific claim, using
deeply on the evidence.
evidence from the table:
Archaeopteryx represents an intermediate link
between birds and dinosaurs.

Guiding Student Thinking

In response to the prompt defending the scientific claim, the specific evidence
students mention will vary but they should highlight the evidence that points to some
characteristics of only dinosaurs and only birds. For example, they can highlight that
Archaeopteryx had teeth and a bony tail like dinosaurs but had a fused wishbone and
longer arm bones like modern birds.

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 Key Concept EVO 1: Patterns of Evolution
Lesson 2.1: Launch Lesson – Examining Evidence of Evolution
Lesson 2.1: Launch Lesson – Examining Evidence of Evolution
Unit 2: Evolution

DATA ANALYSIS UNIT 2

HANDOUT
2.1
Use the data in Figure 2 to complete the table.

Modern- Evidence from

Characteristics Theropods Archaeopteryx
Day Birds Phylogenetic Tree
Teeth   Seen in all
theropods but not
birds
Vertebrae extend   Seen in all
into tail theropods but not
birds
Four digits  First seen in
Eoraptor around
230 mya
Claws on wings   Seen in
Archaeopteryx 150
mya
Hollow bones First seen in
   coelophysoids
between 230 and
220 mya

Hollow and    Both first seen in

tufted feathers tyrannosauroids
between 170 and
160 mya
Three digits    First seen in
allosaurids and
tyrannosauroids
between 170 and
160 mya
Fused furcula   Seen in
(wishbone) Archaeopteryx
150 mya
Longer arm   Seen in
bones Archaeopteryx
150 mya
Feathered  Seen in modern
(boneless) tail birds only between
130 and 120 mya
Toothless beak  Seen in modern
birds only between
130 and 120 mya

Pre-AP Biology Handout 2.1 4 Student Resource

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 Key Concept EVO 1: Patterns of Evolution

UNIT 2 LESSON 2.2

Examining Anatomical Evidence

AREA OF FOCUS
from Fossils – Spinosaurus
ƒ Emphasis on Analytical
Reading and Writing
OVERVIEW

SUGGESTED TIMING
LESSON DESCRIPTION
Part 1: Finding Spinosaurus ~60 minutes
Students analyze the first part of the National
Geographic article on Spinosaurus to gain HANDOUTS
background information on the Kem Kem fossil ƒ 2.2.A: Searching for
beds and the type of anatomical evidence the Spinosaurus
paleontologists are examining. ƒ 2.2.B: Unearthing
Part 2: Unearthing Anatomical Evidence from Anatomical Evidence
Spinosaurus from Spinosaurus
In this next part of the lesson, students extract
crucial information from the article to analyze MATERIALS

key anatomical features of Spinosaurus that ƒ LCD projector,

provide insight into its ecological role and electronic whiteboard,
environment. or other technology
for displaying a text
CONTENT FOCUS
document and an
In the launch lesson for this key concept, students online video
were introduced to the idea that anatomical features ƒ internet access
provide scientists with lines of evidence to establish to the National
evolutionary relationships. Now students have an Geographic video
opportunity to examine the anatomical features of “Nizar Ibrahim: Lost
Spinosaurus, make claims about the function of those Giant of the Sahara”
features, and draw inferences about Spinosaurus’s (15:12), available
ecological role and surrounding environment. Students at https://www.
will need to recall concepts from Unit 1 that are youtube.com/
associated with ecological roles (e.g., carnivore versus watch?v=NaWERiPJagk
herbivore) to draw inferences about Spinosaurus. ƒ highlighters or markers
for text annotation
(optional)

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus

COURSE FRAMEWORK CONNECTIONS UNIT 2

Enduring Understandings

ƒ The theory of evolution states that all organisms descend from a common
ancestor and share some characteristics.
ƒ Biological evolution is observable as phenotypic changes in a population over
multiple successive generations.

Learning Objectives Essential Knowledge

EVO 1.1(a) Use scientific evidence EVO 1.1.2 Scientists use various sources
to justify a claim of an evolutionary of evidence to establish evolutionary
relationship between species. relationships between organisms.
a. Fossil evidence, in conjunction with
relative and radiometric dating, provides
insight into the geographic and temporal
distribution of species throughout Earth’s
history.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus

UNIT 2 PART 1: FINDING SPINOSAURUS

In Part 1 of the lesson, students learn about the exciting discovery of Spinosaurus by
reading the first part of the National Geographic article “Mister Big.” In this part of the
reading, students are introduced to the main scientist in the article, a paleontologist
named Nizar Ibrahim, and the field study site in Morocco where the Spinosaurus fossils
were discovered—the Kem Kem fossil beds.
ƒ To begin, students should read approximately
Meeting Learners’ Needs
half of the National Geographic article “Mister
Some students may find
Big,” found on Handout 2.2.A: Searching
it challenging to apply
for Spinosaurus. You can have students work some of the text-analysis
independently through the reading or work strategies. To help students
in pairs. Tell students to stop at the end of engage with the article, it
paragraph 11. They should use text-analysis could be helpful to first
strategies, such as highlighting and summarizing, model for students how to
use these strategies. You
to capture key concepts from the reading. Remind
may choose to display the
students to record annotations and summaries in
text for the whole class or
the notes section of the handout. lead a guided discussion to
ƒ Some students may run across a few words that remind students of these
are unfamiliar to them. Have students circle these strategies, which have been
used in prior lessons.
words and encourage them to discuss the meaning
of these terms with their reading partner or during
the whole-class discussion.
ƒ Once students have finished reading the first half of the article, it is important to
stop and unpack some of the important information they should have extracted
from it. Use the following questions to guide a whole-class discussion about the
article:
u What images come to mind when you read about the Kem Kem fossil beds?
u What evidence from the article indicates this area is rich in fossils from many
species?
u What type of conditions do you think must have existed during the Cretaceous
period to produce an area with such diverse fossil evidence of life?
ƒ To help students further contextualize information in this article, you may want
to locate and display some online images and other visual information about the
Kem Kem fossil beds, located in northern Africa along the border of Algeria and
Morocco. A map is provided on the next page.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus

UNIT 2

Map of the Kem Kem fossil beds. Credit: © 2016 Hendrickx et al. CC BY 4.0.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0144695.

Instructional Rationale

This lesson is designed to engage students in analyzing an extended reading. It is

important for students to practice this skill as they will have science-based extended
reading passages on the SAT. This also helps students practice for the type of analytical
reading they will utilize in higher-level science courses.

ƒ You may also want to deepen this discussion by showing students the figure on the
next page, which models the stratigraphy of the Kem Kem beds.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus

UNIT 2
Classroom Ideas
Students may have some
idea of how rock layers
form from middle school
science courses. But if
students haven’t been
introduced to relative and
radiometric dating yet, you
may want to provide a brief
overview prior to showing
the rock layers of the Kem
Kem fossil beds. Nature
provides a summary of
these processes at https://
www.nature.com/
scitable/knowledge/
library/dating-rocks-and-
Stratigraphy of the Kem Kem fossil beds. Credit: © 2016 Hendrickx et fossils-using-geologic-
al. CC BY 4.0. http://journals.plos.org/plosone/article?id=10.1371/journal.
methods-107924044.
pone.0144695.

Guiding Student Thinking

The launch lesson explained that unique conditions are needed to preserve remains
as fossils. You may need to prompt students to recall what they know about desert
biomes from Unit 1 to look for key characteristics of the environment mentioned in
the article. For example, “great meandering rivers had flowed there a hundred million
years ago” (paragraph 11) is evidence that that environment was primed for fossil
formation. The map of the Kem Kem fossil beds will help students identify a hot, dry
desert environment with high cliffs and exposed layers of rock. Descriptions in the
text, such as “Stromer found some 45 different taxa of dinosaurs, crocodiles, turtles,
and fish” (paragraph 2), provide evidence of species diversity. Encourage students to
cite specific evidence from the text to support their answers.

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 Key Concept EVO 1: Patterns of Evolution

Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus

PART 2: UNEARTHING ANATOMICAL EVIDENCE FROM SPINOSAURUS UNIT 2

In Part 2 of the lesson, students finish reading the rest of the article, which can
be done individually or with a partner. Students should continue using their text-
analysis strategies to extract important information. In the second half of the article,
students focus on how anatomical evidence can provide clues to the ecological role of
Spinosaurus.

ƒ Before students begin reading the second half of the article, use the following
question to help focus their analysis:
u What anatomical evidence provides clues about the ecological role Spinosaurus
played in its environment?
ƒ Once students are finished reading the remaining part of the article, provide
them with Handout 2.2.B: Unearthing Anatomical Evidence from Spinosaurus.
Students should work in pairs to populate the table and draw inferences about
Spinosaurus using information from the article.
ƒ After student pairs have completed the table and inference questions, show the
following 15-minute video about Spinosaurus from National Geographic, available
at the following link: https://www.youtube.com/watch?v=NaWERiPJagk. Prompt
students to evaluate their claims about Spinosaurus’s ecological role and its
environment as they watch the video, and revise their claims as needed.
ƒ Next, have student pairs merge with another group (forming groups of four, if
possible). Have groups compare and contrast their tables and inferences. Students
should make any needed revisions to their own work based on their peer-to-peer
critique and dialogue.
ƒ After student groups have had ample time to work, have each group share their
table with the whole class in order to generate one collective data table that you can
display. The portion of the student handout on the next page shows an example of
how students might complete the table using information from the text.

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 Unearthing Anatomical Evidence HANDOUT
2.2.B
from Spinosaurus
Key Concept EVO 1: Patterns of Evolution
Observations About Structure and Function in Spinosaurus
Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus
Use the information provided in the article “Mister Big” to complete the following table.
Fill in a description of each anatomical structure of Spinosaurus and its probable function.
UNIT 2
Anatomical Probable Function in
Description
Structure Spinosaurus

Nostrils Nostrils set very high on the Nostrils may have allowed
skull toward the eyes breathing while the rest of the head
was still submerged in water.

Openings in skull at Pits similar to the pressure These may help detect prey in
end of snout sensors that crocodiles and murky water.
alligators have

Jaw and teeth Slender and elongated jaw; This type of jaw and smooth,
smooth and cone-shaped cone-shaped teeth are well suited
(conical) teeth for snaring fish in the water.

Forelimbs Bulky Bulky forelimbs may have

allowed for walking on all four
limbs (functional quadruped).

Hind limbs Disproportionately short Hind limbs are perfectly

and slender proportioned for paddling
in water.

Bones Long, with bone density The bone density would have
similar to that of aquatic allowed for more buoyancy in the
mammals water.

Feet and claws Flat claws that may have Webbing would allow for better
also allowed for webbing on swimming capabilities.
the feet

Sail (dorsal spines) Smooth bones that They may have supported a
protrude from the back/ dorsal sail like those seen in
spinal column modern lizards and chameleons.

Handout 2.2.B

Then, invite
Student Resource
ƒ student groups to share and15discuss their claims about Spinosaurus Pre-AP Biology
© 2021 College Board
from the set of inference questions. Encourage students to identify evidence to
support their claims using the table. The portion of the handout on the next page
provides sample student responses.

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Why is it important to understand the functions of Spinosaurus’s anatomical

characteristics?
How does anatomical fossil evidence help scientists connect lines of evidence for
evolutionary relationships between species?

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 Key Concept EVO 1: Patterns of Evolution
Lesson 2.2: Examining Anatomical Evidence from Fossils: Spinosaurus
Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus
Unit 2: Evolution

HANDOUT Drawing Inferences About Spinosaurus UNIT 2

2.2.B

1. Why did Ibrahim conclude that the dorsal spines were not used to support a
hump or to regulate body temperature?
The bones were smooth and not capable of supporting the soft tissue of a hump,
like those seen in bison. Also, the spines had “few channels for blood vessels, so it
seemed unlikely that they were used to regulate body temperature.”

2. How was Ibrahim able to confirm that Spinosaurus was the largest carnivore to
ever walk the Earth?
He used digital computer modeling to reconstruct the spacing of the vertebrae
of Spinosaurus. This confirmed that the dinosaur was 50 feet “from nose to tail,”
whereas T. rex was approximately 41 feet tall.

3. (a) Based on the evidence in the table, make a claim as to what kind of
environment Spinosaurus lived in.
Answers will vary.

(b) Select the three most compelling pieces of evidence that support your claim.
Answers will vary.

(c) Explain how this evidence supports your claim.

Student answers to the questions above will vary. However, they should indicate
that Spinosaurus was a large carnivore that spent much of its time in aquatic
environments. They could highlight anatomical evidence such as webbed feet,
hind-limb-to-body ratios that are useful for swimming, nostrils located high on
the head to allow breathing while submerged in water, or pits in its snout that
sense prey in murky water.

Handout 2.2.B Student Resource

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 Key Concept EVO 1: Patterns of Evolution
Lesson 2.2: Examining Anatomical Evidence from Fossils: Spinosaurus
Lesson 2.2: Examining Anatomical Evidence from Fossils – Spinosaurus
Unit 2: Evolution

UNIT 2
4. The theropod Spinosaurus seems to share several characteristics with other HANDOUT
2.2.B
aquatic predators, like the crocodile. Based on the phylogenetic tree, describe how
closely related they actually are to one another. What modern-day organism are
they more closely related to?

crocs
crocs && horned dome- armored other
relatives
relatives pterosaurs dinos heads duckbills dinos sauropods prosauropods theropods birds

theropods

ornithischians
saurischians

dinosaurs

ornithodirans

archosaurs

Adapted from “Meet the Relatives: A Dinosaur Family Tree.” © 2005 by the University of California Museum
of Paleontology, Berkeley. www.ucmp.berkeley.edu/museum/events/bigdinos2005/turkey.html.

Theropods are not closely related to the crocodile. Their last common ancestor is
the archosaurs group. Theropods are more closely related to modern-day birds.

Handout 2.2.B

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 Key Concept EVO 2: Mechanisms of Evolution

LESSON 2.3 UNIT 2

Launch Lesson – Variation in Asian Ladybugs

OVERVIEW

LESSON DESCRIPTION AREA OF FOCUS

Part 1: Making Connections to the Hierarchy of ƒ Emphasis on Analytical
Life Reading and Writing
In the first part of the lesson, students closely
observe the phenotypic variances of the Asian
SUGGESTED TIMING
ladybug. They then use this context and prior
Less than 45 minutes
knowledge to describe the levels in the hierarchy
of life and provide examples of each.
HANDOUTS
Part 2: Using Observations to Make Inferences
ƒ 2.3.A: Ladybugs and
About Ladybugs
the Environment
Students work in pairs to think about how
ƒ 2.3.B: Hierarchy of Life
phenotypic variations in an Asian ladybug
Cards
population may influence survival and
reproduction. They are also asked to predict what
MATERIALS
may change if the environment changes.
ƒ LCD projector,
electronic whiteboard,
CONTENT FOCUS
or other technology for
The focus of this lesson is to provide students with
displaying a photo
an opportunity to observe and define phenotype
ƒ digital image of Asian
variance and identify pressures in the environment that
ladybug phenotype
may influence the variation we see. They will not be
variation
formally introduced to the ideas of selective pressures,
ƒ scissors
differential reproduction, fitness, or adaptation in
this lesson. However, understanding the big picture
of how the environment influences the traits we see
in populations will prepare them to dive into those ideas in the next lesson for Key
Concept EVO 2 (Lesson 2.4: Modeling Natural Selection Lab).

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs

UNIT 2 COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological evolution is observable as phenotypic changes in a population over

multiple successive generations.
ƒ Speciation, extinction, and the abundance and distribution of organisms occur in
response to environmental conditions.

Learning Objectives Essential Knowledge

EVO 2.2(a) Describe how selective EVO 2.2.1 Darwin’s theory of natural
pressures in the environment can affect selection is that a selective mechanism
an organism’s fitness. in biological evolution may lead to
adaptations.
a. Abiotic ecosystem components
(e.g., nutrients) and biotic ecosystem
components (e.g., predators) act as
selective pressures.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs

PART 1: MAKING CONNECTIONS TO THE HIERARCHY OF LIFE UNIT 2

The goal of this part of the lesson is to have students make direct connections to
concepts from Unit 1: Ecological Systems and to elicit their prior knowledge about the
levels of organization found within ecological systems.

ƒShow students the collection of photos of the Asian lady beetle (or ladybug),
Harmonia axyridis. Before you explain to students that these images are all one
species, ask them to closely observe the photo and record all their observations.

Photos of Harmonia axyridis. Credit: © Entomart. https://commons

.wikimedia.org/wiki/File:Harmonia_axyridis01.jpg.

Lead a whole-class discussion by asking the following questions:

What do you notice about the beetles?
Do you think this is a picture of one species or more than one species? Why?
What information would you need to know in order to determine if it is just one
species?

Guiding Student Thinking

During the discussion, students should point out the variations in color and spot
patterns. The physical diversity may lead some students to think that this image shows
many different beetle species. However, students should remember that members of a
species must be able to breed and produce fertile offspring with one another. Students
can conclude that in order to determine if the beetles are the same species, they need
to know if the beetles can produce viable offspring.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs

UNIT 2 You can now confirm for students that the photos do show members of one species: the
Asian ladybug, Harmonia axyridis. Have students examine the background information
about this species provided at the top of Handout 2.3.A: Ladybugs and the Environment.

ƒ Have students work in pairs to complete Part 1 of

Classroom Ideas
the handout. Students should fill in a description
You can have students
and an example on each of the provided cards
cut out the cards either
about the hierarchy of life (see Handout 2.3.B: before or after they have
Hierarchy of Life Cards). To do this, students completed filling in
should draw on their prior knowledge about their information. They
the structure and hierarchy of life as well as the can then arrange them
background information about the Asian ladybug. in the hierarchy. This
provides a great visual
Finally, have students number the cards to
diagram for students.
construct a hierarchy, starting with the first level of
organization—organism.
1) Organism 2) Population 3) Community 4) Ecosystem 5) Biome 6) Biosphere

ƒ Allow students to share their descriptions and examples with the entire class. Then,
revisit the image of the ladybugs.

PART 2: USING OBSERVATIONS TO MAKE

Meeting Learners’ Needs
INFERENCES ABOUT LADYBUGS
If students have difficulty
In this part of the lesson, students work in pairs to answering the questions in
think about how phenotypic variations in an Asian Part 2 of Handout 2.3.A,
ladybug population may influence survival and you can provide them with a
reproduction. They are also asked to predict what may modified sentence expansion
technique. For example,
change if the environment changes.
the first two questions ask
ƒ Have students continue to work in pairs to answer students to think about how
the questions in Part 2 of Handout 2.3.A, which ladybug traits influence their
explore the effects of the phenotypic differences ability to survive and mate.
Students could use sentence
shared among the population of ladybugs.
expansions as supportive
ƒ Students should begin to formulate ideas prompts to their thinking,
about how different traits may be beneficial such as: “The ladybug traits
or detrimental under various environmental are beneficial to survival,
conditions. While student answers will vary, the because ”
portion of the student handout included at the end or “The ladybug traits are
beneficial to survival, so
.”

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs

of this lesson provides insight into what type of answers they should generate. It’s UNIT 2
important that students can simply list as many ideas about benefits or detriments
to organisms as they can think of.

Instructional Rationale

The point of this part of the lesson is simply for students to start thinking about what
type of traits may or may not be beneficial to organisms in the environment and
how these traits may lead to differences in organisms’ chances for reproduction. This
helps scaffold students’ understanding of the idea of differential reproduction, which
is critical in the next lesson on natural selection. It’s also key to introduce the term
phenotype here to describe difference in traits. Students are more likely to remember
these terms when they can attach them to an authentic context, such as variations in
ladybug coloration.

ƒ After students have had ample time to work on these questions, lead a whole-class
discussion in which you invite student groups to share their ideas with the entire
class.
ƒ By the end of the class discussion, the following important ideas should emerge
from the conversation. It would be helpful for you to record them on the board for
students to see:
u Even though populations are made up of one species, individuals in the
population may demonstrate different physical traits (phenotypes).
u The differences in traits may influence the survival and/or the reproductive
success of the individual.
u If the individual survives, they can pass along those genes to the next generation.

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 Key Concept EVO 2: Mechanisms of Evolution
Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs
Lesson 2.3: Launch Lesson – Variation in Asian Ladybugs
Unit 2: Evolution

UNIT 2 PART 2: USING OBSERVATIONS TO MAKE INFERENCES ABOUT LADYBUGS

HANDOUT
2.3.A
Think about a population of ladybugs that has all the phenotypic differences you
observed. Consider how those differences impact the species.

1. How might the variety of traits affect the survival of the ladybugs?
Benefits include: 1) warning coloration to decrease predation and 2) darker colors
that absorb more sunlight, allowing ladybugs to stay warmer in colder climates.
Note: It is still productive if students think about camouflage as a possible benefit.
However, they should see that in this case the ladybug coloration actually makes
them stand out in their environment.
2. How might the variety of traits affect the reproduction of individuals?
Traits that allow organisms to survive by decreasing predation increase their chances
of reproduction. Also, certain coloration variances may be more helpful in attracting
mates, thereby increasing chances of reproduction.

3. Describe how traits (phenotypes) and reproduction of ladybugs are connected to

one another.
If a trait (phenotype) helps an organism survive or attract mates, then the organism
will likely have more opportunities to reproduce than organisms who do not have
that trait.

4. Explain why survival and reproductive success may not be equal for all
individuals in this population.
Since the ladybugs have different coloration, they may experience different abilities
in escaping predators or attracting mates.

5. Describe how changes in the ladybugs’ environment may influence their survival
or reproduction.
If the environment changes, then the coloration (or trait) they have may not be as
beneficial for them. For example, if the climate warms in a given area, then darker
coloration in ladybugs may not be as beneficial as it was in colder environments.

Handout 2.3.A

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 Key Concept EVO 2: Mechanisms of Evolution

LESSON 2.4 UNIT 2

Modeling Natural Selection Lab

AREA OF FOCUS
ƒ Attention to Modeling
OVERVIEW

LESSON DESCRIPTION SUGGESTED TIMING

Part 1: Data Collection for Natural Selection ~180 minutes

Simulation
Students are first introduced to the context that HANDOUT
they will be modeling: survival rate of brown- ƒ 2.4: Modeling Natural
lipped snails. They then collect data using the Selection
protocol for the model.

Part 2: Data Analysis for Natural Selection MATERIALS

Simulation ƒ three colors of beans
After students have collected data, they analyze their (e.g., black beans,
results by graphing the frequencies of brown-lipped kidney beans, and navy
snails for each generation. They then work in small beans)
groups to make evidence-based claims about the ƒ electronic whiteboard,
characteristics necessary in a population to allow LCD projector, or
change over time. Finally, students participate in other technology for
a whole-class discussion to summarize their ideas displaying images and
about the process of natural selection. showing online videos
(optional)
Part 3: Modification of the Natural Selection
ƒ internet access to
Model
one of the following
Students return to the snail model and modify
videos (optional):
some of the parameters. They then make
http://statedclearly.
predictions about what they may see and model
com/videos/what-
their predictions. Finally, students engage in
is-natural-selection
some peer-to-peer review and discussion of each
(9:18) or https://ed.ted.
other’s modifications and analysis.
com/lessons/myths-
and-misconceptions-
CONTENT FOCUS
about-evolution-alex-
During this exploratory laboratory lesson, students
gendler (4:22)
model the changes in phenotype frequencies in a prey
population over three generations. They should begin
to develop an understanding of what is required for
a population to change over time through natural

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2 selection by analyzing data through guided small-group discussions and whole-class
discussions. Later in the lesson, students return to the model and investigate what
happens to the same population when they modify the parameters of the model and
run the investigation again.

The practice performance task that follows this lesson provides an opportunity for
students to practice writing evidence-based claims and applying their knowledge of
natural selection to real data sets. The task can also be used before Part 3 of this lesson.
COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological evolution is observable as phenotypic changes in a population over

multiple successive generations.
ƒ Speciation, extinction, and the abundance and distribution of organisms occur in
response to environmental conditions.

Learning Objectives Essential Knowledge

EVO 2.2(a) Describe how selective EVO 2.2.1 Darwin’s theory of natural
pressures in the environment can affect selection is that a selective mechanism
an organism’s fitness. in biological evolution may lead to
EVO 2.2(b) Explain how selective adaptations.
pressures in the environment could a. Abiotic ecosystem components
cause shifts in phenotypic and/or allele (e.g., nutrients) and biotic ecosystem
frequencies. components (e.g., predators) act as
EVO 2.2(c) Use data to describe how selective pressures.
changes in the environment affect b. Favorable traits in a given
phenotypes in a population. environment lead to differential
EVO 2.2(d) Predict how allelic reproductive success, or fitness, and over
frequencies in a population shift in time can produce changes in phenotypic
response to a change in the environment. and/or allele frequencies.
c. Heritable traits that increase an
organism’s fitness are called adaptations.
d. Over time, the relative frequency of
adaptations in a population’s gene pool
can increase.
e. Patterns of natural selection can include
phenomena such as coevolution, artificial
selection, and sexual selection.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2
EVO 2.2.2 Favorable traits are relative to
their environment and subject to change.
a. Changes in the environment happen
both naturally (e.g., floods, fires, climate
change) and through human-induced
activities (e.g., pollution, habitat
destruction, climate change).

SETUP AND PREPARATION NOTES

ƒ The three colors of beans represent dark, intermediate, and light-colored snails. (As
an alternative to beans, other materials such as different colors of hole-punched
paper can be used.)
ƒ There are several ways to simulate the “environment” for this lab. The most common
are to use a colorful or patterned fabric to place the bean on, or to use colored
poster paper to place different colored hole-punches (including the color of the
background). Keep in mind that the goal is for at least one phenotype of the snail
(beans or hole-punch) to have a survival advantage in that given environment (fabric
or poster paper) so that they are chosen less often by the predatory birds (students).
ƒ For each lab group, prepare a bag with 25 beans of each color (i.e., dark,
intermediate, and light). This will represent the initial population of snails.
ƒ Prepare additional bags with 50 beans of each color for each lab group to speed up
the transition between generations of the simulated populations.
ƒ If you have a large enough area outside to conduct this lab, then students can
“hunt” for beans in a grassy area. You should pre-mark a plot of grass for this ahead
of time. You may use one large plot with your students or several smaller plots for
individual lab groups.
ƒ If using large fabric or poster paper for your background, it should be pre-cut for
each student group.

Additional Lab Materials

u containers for sorting beans
u plastic spoons
u small paper or plastic cups
u graph paper
u stopwatch or timer
u clipboard for student recorders when outside (optional)

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2 INTRODUCTION: STUDENT MISCONCEPTIONS ABOUT NATURAL

SELECTION
In this laboratory lesson, students have an opportunity to model natural selection and
then evaluate what characteristics must exist in a population for it to evolve. During
this in-depth lesson, students collect and analyze data to draw conclusions about
natural selection.

Guiding Student Thinking

There are many common misconceptions about natural selection that can make
it harder for students to develop a deep and appropriate understanding of this
concept. It can be very difficult to uncover misconceptions without asking targeted
discussion questions. It may be helpful to explore some of the common student
misconceptions prior to engaging in this investigation. We have provided a list of four
common misconceptions to be aware of below. However, the University of California,
Berkeley, has compiled a longer list of misconceptions that exist about evolution and
natural selection, which is available at https://evolution.berkeley.edu/evolibrary/
misconceptions_faq.php#a3.

ƒ Listed below are four misconceptions to look out for during this lesson and how to
address them:
1. Students may understand variants in a population to mean “different species.”
To help prevent this misconception from developing, reinforce the idea that the
snails (beans) all belong to a population of the same snail species—the brown-
lipped snail.
2. Students may understand natural selection (and evolution in general) as directional
and purposeful. Help students avoid constructing explanations that use the language
of agency. Words like “need,” “try,” or “want” to describe change can reinforce the
misconception that a species is purposefully improving toward a solution.
3. Students may think that natural selection is a random process. This is incorrect.
Explain that natural selection is a natural process that occurs as a result of
interacting factors in an ecosystem, such as variation and selective pressures that
already exist in the environment in which the population occurs. Mutation, the
genetic source of the variation that is found, is random; natural selection is not.
4. Students may believe that fitness is all about an individual’s survival, even after
hearing a careful definition and explanation of fitness as the ability to leave
offspring in the next generation. Return to this idea frequently and probe student
understanding through regular discussion to uproot this misconception.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

PART 1: DATA COLLECTION FOR NATURAL SELECTION SIMULATION UNIT 2

In the first part of this lesson, students model predation of a brown-lipped snail
population that demonstrates only three of the color variants (dark, intermediate,
light). Students use three different colors of beans (or similar materials) to represent
the population. The simulation requires some prior preparation: beans need to be
sorted into bags; roles need to be assigned to individuals in student groups; students
may need to practice certain roles; and students need to understand the process and
constraints of the simulation. You may want to highlight the following connections
between the simulation and the ecological context.

ƒ To simulate predation of snails by the song thrush, students use a plastic spoon
(beak) to pick up each bean (snail) and put it in a plastic cup (stomach).
ƒ Because the brown-lipped snail is hermaphroditic, and thus can mate with any
snail it runs into, the model can be simplified as follows: for each snail that survives
a hunting round (60 seconds), students simulate it reproducing one offspring, thus
leaving itself and one new snail in the next generation.
ƒ For purposes of this model, we will assume no snail deaths from natural causes
from generation to generation.
This part of the lesson sets students up for Part 2, in which they graph the data and
observe the changes in the variation present in the population. Because this model
shows (1) variation in the population, (2) heritability of that variation, and (3)
selection for (or against) some of the variations in the population, students observe
natural selection. It is best if students have an opportunity to make claims about what
is necessary for natural selection using their data before you explain or summarize
these key ideas.
INTRODUCING THE SCENARIO
ƒ Prior to beginning the simulation, introduce students to the scenario they will
be investigating through modeling. For this lab, we will investigate whether
there is a relationship between phenotypic variation in the brown-lipped land
snail (Cepaea nemoralis) and the predation of this snail by a common predator,
the song thrush (Turdus philomelos). Have students read the introduction on
Handout 2.4: Modeling Natural Selection, and then lead a whole-class discussion
to ensure students understand the context prior to modeling how this predator−
prey relationship may influence color variation in snails. It may also be helpful to
project or display the images from the student handout, included on the next page,
to aid students in viewing color or detail.

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 Key Concept EVO 2: Mechanisms of Evolution
Lesson 2.4: Modeling Natural Selection Lab
Lesson 2.4: Modeling Natural Selection Lab
Unit 2: Evolution

UNIT 2
HANDOUT
2.4

Brown lipped
Handout 2.4 snails and a song thrush. Credit: George Bernard/Science Source (left); Dave Watts/Science
Source (right)

ƒ A few questions that could prompt student thinking during the whole-class
PART 1: DATA COLLECTION FOR THE NATURAL SELECTION SIMULATION
discussion are:
You will now model natural selection in a population of snails over three generations.
u How could snail color variation impact predation by the song thrush?
There are three shell color variations in your population: dark, intermediate, and
u Since brown-lipped snails are not native to the United States, what are some
light. The selective pressure on the population is the song thrush, a visual predator.
possible
Your teacher consequences
will explain of their protocol
the simulation introduction?
and assign roles to each member of
your group. Use the data table on the next page to record the results of your group’s
Guiding Student Thinking
experiment.

Students should have some early thoughts about characteristics of prey, such as
camouflage, that can increase chances of survival. Since the brown-lipped snail is not
native to the U.S. but has been introduced, it is a good time to remind students about
invasive species. Have students consider what could happen to this species of snail
since its main predator, the song thrush, is not in the U.S.

STUDENT ROLES IN THE NATURAL SELECTION SIMULATION

ƒ After introducing students to the scenario they will
Classroom Ideas
be modeling, assign the following roles to students
It may save time to
and provide a brief explanation of what their role consider what roles are
requires. The simulation could be done either as best for which students
an entire class, if you have a large enough area, or prior to class and have
in several smaller groups of three or four students. a list posted. While the
(Recommendations for the number of students majority of students will be
needed for each role are indicated for both small- song thrush birds, the field
biologists and data analysts
group and whole-class simulations.)
are roles that may be better
u Song Thrush Birds: Students in this role will suited for students who are
hunt and consume as many snails as they can detail-oriented or confident
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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

be given a plastic spoon and small cup to simulate the beak and stomach of the UNIT 2
bird. To simulate the behavior of this predator, students will need to learn a specific
hunting behavior. Hunting behavior: Students prey on snails (beans) in the plot
by scooping up one bean at a time with a plastic spoon (beak) and putting it into
a cup (stomach). Starting from a standing position, students must bend down to
get the bean, stand up, and then put the bean in the cup. (If students put a bean
into the cup while bent over, or if they catch and “eat” more than one bean at
a time, they must start the simulation over.) It is helpful to have a few students
demonstrate this technique before the simulation begins. You may choose to do
this demonstration inside, to minimize the amount of instruction that will take
place outside. (Assign this role to one or two students per group, or to most of the
students if it is a whole-class activity.)
u Field Biologist: Students in this role will collect data on the number of snails
(beans) consumed after each round of hunting and report this number to the data
analyst. (Assign this role to one student per group, or one or two students for each
color of bean if it is a whole-class activity.)
u Data Analyst: After each round of hunting, students in this role will record
and organize data in the data table provided. They will also be responsible for
calculating rows C and E. (Assign this role to one student per group, or two
students if it is a whole-class activity.)
NATURAL SELECTION SIMULATION PROTOCOL
1. To begin the simulation, introduce students to the materials being used to simulate
predation on the snails by the song thrush.
2. Have students randomly scatter 25 of each color of “snail” onto the background plot.
These should be evenly scattered, not clumped together.
3. Once the background plot has been populated and the student song thrushes have
been taught how to hunt, set a timer for 60 seconds and let them hunt. This is one
hunting round. At the end of the round, the song thrushes give their different-colored
beans to the field biologists.
4. The field biologists count the total number of each color of snail eaten and report
these data to the data analysts.
5. Data analysts enter the data for Generation 1 in Data Table 1 on the handout, shown
on the next page for reference.
ƒ For rows D and E, remind students of the assumption that each surviving
snail produces one offspring. For example, if there are 10 light-colored snails
remaining, they will each have one light snail offspring. Thus 10 new light snails
should be added to the population, for a total of 20 in the population.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2 ƒ Point out that the population at the end of each hunting Lesson
round2.4:(row E) will be
Modeling Natural Selection Lab
the same as the population at the beginning of the next (row A). Data analysts Unit 2: Evolution
can simply copy row E from the first round into row A of the next.

DATA TABLE 1: COLOR VARIATION IN THE HANDOUT

BROWN-LIPPED SNAIL POPULATION OVER TIME 2.4

Generation 1 Generations 1 and 2 Generations 1, 2, and 3

Dark Inter­ Light Dark Inter­ Light Dark Inter­ Light
mediate mediate mediate
Population 25 25 25
number at the
beginning of
the hunting
A round

(row E of
previous
generation)
Number of
B individuals
eaten during
hunting

Number of
C surviving
individuals
(row A − row B)

Number of
D offspring
(same as row C)

Population
number at
E the end of the
hunting round
(row C + row D)

Handout 2.4

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

6. Field biologists now add the offspring for each color UNIT 2
Classroom Ideas
(row D) to the simulated population in preparation
If there is enough time, it
for the next round. Remind students to scatter the is a good idea to have all
beans when adding them to the population rather the lab groups pool their
than clumping them together. data into one table with
7. Repeat steps 2–6 two more times, as two new the class average for each
trial. This typically results
generations are added to the population.
in better data since it is
based on a large sample,
and will help prevent a
single lab group from
generating ideas about
natural selection based on
a potentially poor data set.

Guiding Student Thinking

Students often struggle with understanding that adaptations and natural selection
do not occur at the individual level. Therefore, it is very important for students to
understand that the change that is happening is between generations of a population.
For brown-lipped snails, a new generation emerges approximately every 2−5 years.
Therefore, these three generations represent a span of time between 6 and 15 years.
This model should promote student thinking about evolution occurring at a population
level over generations and not to a single individual. You may need to emphasize this
with students after the first round of hunting and adding offspring to the population.

PART 2: DATA ANALYSIS FOR NATURAL SELECTION SIMULATION

In this next part of the investigation, students reflect on the data collected as they
construct their own understanding of the process of natural selection. This activity
includes both small, collaborative group discussions and focused whole-class
conversations.
CALCULATING AND GRAPHING RELATIVE FREQUENCY
ƒ First, have each group share their raw data from Data Table 1. Include the totals in
a collective version of Data Table 1 that you can display.
ƒ Next, have each student use the collective data table (for Data Table 1) to populate
Data Table 2 on Handout 2.4. This will require students to calculate the frequency
of each trait in the population for each generation.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2 ƒ Finally, have students individually graph the relative Unit 2: Evolution

Meeting Learners’ Needs

frequency of each color for the snails based on Data
Some students may have
Table 2.y This will allow students to start analyzing the HANDOUT
difficulty understanding
2.4

data collected and to begin identifying trends. what relative frequency

PEER-TO-PEER EVALUATION OF DATA actually means in this
context. These students
ƒ Students will now work in small groups to discuss the
may need additional
data to deepen their understanding of the trends they support in thinking about
observed. In order to support peer-to-peer dialogue, this term as either a ratio
have students use the discussion questions on or a percentage of how
Handout 2.4 shown below to guide them. During often this trait occurs in
the group discussion, circulate around the room and the total population in
this given environment.
provide support as needed. x
Help them understand it
GROUP DISCUSSION QUESTIONS: INVESTIGATIONS INTO NATURAL
is a ratio of snail color to
SELECTION total population size:
Number of snails for each color
1. How did your population change in just one generation versus after three? .
2. What was the most successful color of snail? Why was it so successful?
Total snail population
3. What was the least successful color of snail? Why was it unsuccessful?
4. What do you think would happen to the least successful color if the experiment
were to continue five more generations?
Classroom Ideas
5. What is the relationship between color and reproductive rates in snails? Explain
your reasoning.
You can have groups work
6. Consider your data for this simulation. Would the trends seen in your graph have on the first set of discussion
been the same if: questions together in class,
(a) Color is not heritable (in other words, a snail could have any color of or at home as homework
offspring)?
Lesson 2.4: Modeling Natural Selection Lab Explain your ideas.
if pacing is tight. You
Unit 2: Evolution (b) The environment was different (in other words, the snails weren’t being
hunted in the current environment/background, but instead in another type may also want students
of environment/background)? Explain your ideas. to individually complete
(c) A new mutation arises that results in individuals possessing a green color
HANDOUT
2.4
the final questions as
trait? Explain your ideas.
Student Resource
(d) A nonvisual predator was eating 27
the snails? Explain your ideas.
an opportunity for
Pre-AP Biology
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(e) The light-colored variant has better immunity to a virus that infects the formative assessment.
population? Explain your ideas.
(f) The light-colored snails have five more offspring per round than the rest of
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FINAL QUESTIONS: NATURAL SELECTION

1. Explain how the color of the snails influenced the frequency of the different
colors found in the population after three generations.
2. Predict how the population of each color snail may change over 10 more
generations. Explain your reasoning.
3. Can you think of any other variables that may have altered how the distribution of
variation in the population of snails changed over time?
4. Consider the ideas you have discussed in the questions above. As a group, list
three factors that must exist in a population for change to occur over generations.

Handout 2.4

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2
Guiding Student Thinking

These questions are intended to help students make connections between the trait
variations in populations, heritability of those traits, and selective pressures for or
against those traits. Encourage students to think about how the color variation in
the population may lead to different survival rates (e.g., some colors are easier for
predators to see). Also have them consider how a change in a variable, such as the
color of the background environment, could result in selection favoring a new trait.
Students should see that the relative frequency of traits in the population (color
variations in the snails) is therefore influenced by the selective pressure of predation
from the birds; this pressure will continue to influence the relative frequency of
traits in the population over the next few generations if conditions remain the same.
It may be helpful to ask students to generate a list of heritable versus nonheritable
characteristics that could be influenced by predation.

CLASS DISCUSSION AND SHARING OF GROUP IDEAS

ƒ Once groups have answered the group discussion questions and final questions,
bring the class together to discuss their answers and explanations. Generate a
whole-class list of student responses to the final question (question 4, the factors
necessary in a population to result in change over time). Lead the class in a
discussion to help them evaluate each of the ideas on the list. Cross off ideas as
students collectively decide that a factor is not necessary. In the end, only three
characteristics should remain:
u Variation
u Heritability of that variation
u Selection for (or against) one or more of the heritable variants
ƒ To conclude this part of the investigation, you may want to show a video to help
students connect their new understanding about the process of natural selection
with the concepts they learned about common descent with modification (Key
Concept EVO 1: Patterns of Evolution). One possible resource is the Stated
Clearly video “What Is Natural Selection?” (http://statedclearly.com/videos/
what-is-natural-selection). A second option is the TED Ed video, “Myths and
Misconceptions About Evolution” (https://ed.ted.com/lessons/myths-and-
misconceptions-about-evolution-alex-gendler).

PART 3: MODIFICATION OF THE NATURAL SELECTION MODEL

In this part of the lesson, students revisit the model involving color variation in snails
to deepen their understanding of the factors that influence evolution by natural
selection in populations. Student groups propose a modification to the original model

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2 and predict whether or how it changes the outcome of natural selection. Students
GROUP
then DISCUSSION
test their predictionsQUESTIONS: INVESTIGATIONS
by running a second INTOcollect
simulation. They NATURAL
data, analyze
SELECTION
and compare data across simulations, and present an explanation for how their
modifications influenced the effects of natural selection in their model populations.
1. How did your population change in just one generation versus after three?
STUDENT MODIFICATIONS TO THE SIMULATION PROTOCOL
2. What was the most successful color of snail? Why was it so successful?
ƒTo begin, prompt student groups to think about how they would like to modify
3. What was the least successful color of snail? Why was it unsuccessful?
their model. Ask students to revisit their group discussion questions from
4. What do
Handout 2.4,you thinkbelow.
shown would In
happen to the student
particular, least successful colortoifquestion
responses the experiment
6 may
were to continue five more generations?
spur their creativity as they revise the snail model, so you could display the
5. What isand
questions the allow
relationship
groupsbetween
time tocolor and reproductive rates in snails? Explain
reflect.
your reasoning.
6. Consider your data for this simulation. Would the trends seen in your graph have
been the same if:
(a) Color is not heritable (in other words, a snail could have any color of
offspring)?
Lesson 2.4: Modeling Natural Selection Lab Explain your ideas.
Unit 2: Evolution (b) The environment was different (in other words, the snails weren’t being
hunted in the current environment/background, but instead in another type
of environment/background)? Explain your ideas.
HANDOUT (c) A new mutation arises that results in individuals possessing a green color
2.4
trait? Explain your ideas.
(d)
Student Resource A nonvisual predator was eating 27
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(e) The light-colored variant has better immunity to a virus that infects the
population? Explain your ideas.
(f) The light-colored snails have five more offspring per round than the rest of
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Handout 2.4
FINAL QUESTIONS: NATURAL SELECTION

Student proposals may include modifications to the model such as changing the
1. Explain how the color of the snails influenced the frequency of the different
reproductive rate of one of the variants; starting the population with more or less
colors found in the population after three generations.
variation; changing the environment (gravel or dirt instead of grass, or a different color
2. Predict how the population of each color snail may change over 10 more
fabric or background than the one used); or removing heritability of the color trait.
generations. Explain your reasoning.
Next, have student groups write new protocols, taking the following into account:
3. Can you think of any other variables that may have altered how the distribution of
Can the idea
variation in thebepopulation
modeled?ofHow?
snailsAre additional
changed supplies needed?
over time?
If the original
4. Consider experiment
the ideas you have was done as
discussed in athe
whole class, above.
questions how canAs the protocol
a group, list
be modified for a small group of students? Factors to consider include size
three factors that must exist in a population for change to occur over generations. of
hunting plot, original population size, and how to assign all the necessary roles to
group members.

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 Key Concept EVO 2: Mechanisms of Evolution

Lesson 2.4: Modeling Natural Selection Lab

UNIT 2
Instructional Rationale Classroom Ideas
To help alleviate in-class
The focus here is to allow students to engage in an time constraints, students
inquiry-based approach to changing the prior model could collaborate on a
of natural selection. Inquiry-based investigations shared Google Doc outside
are extremely important as they elevate students’ class to design the modified
critical thinking, allow deeper engagement in science protocol so they are ready
practices, and often increase student engagement to begin the simulation
overall. Student choices about modification also serve the next day. Groups
as a highly valuable way to assess what students know could also trade their
about mechanisms of natural selection at this point. experimental protocols and
Therefore, it is beneficial to really allow students to have peer edit for clarity and
ownership over changing the protocol. However, some completion. This will save
choices by students may result in additional confusion class time and promote
about natural selection if they don’t fully attend to the peer-to-peer discussion
questions above. So, this is also a good opportunity for and learning. If class
students to practice developing appropriate scientific time is not a constraint,
questions and predictions, which sometimes requires a students could produce
bit more teacher guidance. their protocol on chart
paper and peer-to-peer
DATA COLLECTION AND ANALYSIS FOR collaboration could occur
THE REVISED MODEL through a gallery walk.
Since each modeling protocol may be different, student
groups will need to develop their own tables for collecting their data. Students may also
need some graph paper for analysis.

ƒ Allow students time to run the new simulation and collect data using their
modified protocols.
ƒ Provide student groups with whiteboard space or large banner or chart paper and
prompt them to:
u Write an explanation of how they modified the original protocol.
u Sketch a graph of their data.
u Determine whether natural selection occurred in their model, and support their
claim with evidence. (Was there variation, heritability, and selection? Can they
explain the evidence for each?)
u Consider whether their model had a similar outcome to the original model and
explain why or why not.
ƒ Finally, give each group a few minutes to present their findings to the class.
Encourage peer-to-peer dialogue and discussion about each group’s findings and
how they modeled the process of natural selection.

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 Practice Performance Task: Tusklessness in African Elephants

UNIT 2 PRACTICE PERFORMANCE TASK

Tusklessness in African Elephants

OVERVIEW

DESCRIPTION AREAS OF FOCUS

Students have an opportunity to demonstrate ƒ Emphasis on Analytical
their understanding of natural selection by Reading and Writing
investigating a new context: tusklessness in ƒ Strategic Use of
African elephants. Mathematics

CONTENT FOCUS SUGGESTED TIMING

This practice performance task is designed to be used ~45 minutes
in conjunction with Lesson 2.4: Modeling Natural
Selection Lab in this key concept (Key Concept EVO 2:
HANDOUT
Mechanisms of Evolution). The task challenges
ƒ Practice Performance
students to transfer the knowledge about natural
Task: Tusklessness in
selection they have developed thus far to a new
African Elephants
scenario, tusklessness in African elephants.

This is a good opportunity to assess student MATERIALS

understanding of the natural selection model they
ƒ electronic whiteboard,
investigated in Lesson 2.4, prior to them engaging in
LCD projector, or other
the performance task for this unit. You can also use this
technology for showing
task as a formative assessment between Parts 2 and 3 of
an online video
Lesson 2.4.
ƒ internet access to the
HHMI BioInteractive
video “Selection for
Tuskless Elephants”
(6:40), available
at https://www.
biointeractive.org/
classroom-resources/
selection-tuskless-
elephants

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 Practice Performance Task: Tusklessness in African Elephants

COURSE FRAMEWORK CONNECTIONS UNIT 2

Enduring Understandings

ƒ Biological evolution is observable as phenotypic changes in a population over

multiple successive generations.
ƒ Speciation, extinction, and the abundance and distribution of organisms occur in
response to environmental conditions.

Learning Objectives Essential Knowledge

EVO 2.2(a) Describe how selective EVO 2.2.1 Darwin’s theory of natural
pressures in the environment can affect selection is that a selective mechanism
an organism’s fitness. in biological evolution may lead to
EVO 2.2(b) Explain how selective adaptations.
pressures in the environment could a. Abiotic ecosystem components
cause shifts in phenotypic and/or allele (e.g., nutrients) and biotic ecosystem
frequencies. components (e.g., predators) act as
EVO 2.2(c) Use data to describe how selective pressures.
changes in the environment affect b. Favorable traits in a given
phenotypes in a population. environment lead to differential
EVO 2.2(d) Predict how allelic reproductive success, or fitness, and over
frequencies in a population shift in time can produce changes in phenotypic
response to a change in the environment. and/or allele frequencies.
c. Heritable traits that increase an
organism’s fitness are called adaptations.
d. Over time, the relative frequency of
adaptations in a population’s gene pool
can increase.
e. Patterns of natural selection can
include phenomena such as coevolution,
artificial selection, and sexual selection.
EVO 2.2.2 Favorable traits are relative to
their environment and subject to change.
a. Changes in the environment happen
both naturally (e.g., floods, fires, climate
change) and through human-induced
activities (e.g., pollution, habitat
destruction, climate change).

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 Practice Performance Task: Tusklessness in African Elephants

UNIT 2 SUPPORTING STUDENTS

BEFORE THE TASK
ƒ To introduce the new context, have students watch “Selection for Tuskless
Elephants” (https://www.biointeractive.org/classroom-resources/selection-
tuskless-elephants). This video on the phenomenon of tusklessness in
Mozambique’s Gorongosa National Park provides an introduction to the work
of Dr. Joyce Poole. Poole studies how poaching is influencing the frequency of
tusklessness in African elephants.
ƒ After students watch the video, have them read the introduction on the handout
Practice Performance Task: Tusklessness in African Elephants. Then lead a
whole-class discussion to ensure that students understand the new context prior to
letting them complete the questions. Some probing discussion questions may be:
u What are tusks? How do they support an elephant’s role as an herbivore?
Tusks are elephants’ incisor teeth. Because they are herbivores, elephants use their
tusks to help them obtain plant matter to eat—by stripping off the bark from
trees, for example.
u How are the research findings on tusklessness in the national parks of Zambia
and Uganda similar to Dr. Poole’s findings in Gorongosa National Park?
All the parks are seeing increased frequency in tuskless elephants, particularly
females, due to poachers who are killing the elephants that have tusks.
DURING THE TASK
ƒ Next, have students complete the questions on the handout. The first question
has them calculate potential frequencies of the tusklessness trait in the Gorongosa
National Park elephant population. Students then use evidence from the text and
their data to craft sentences explaining why the frequency of tusklessness in the
male population differs from that of the female population. As practiced in Unit 1,
each sentence will use one of the following conjunctions: but, because, so. Finally,
students are asked to use the principles of natural selection to explain the increase
in tusklessness in the elephant population as a whole.

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 Practice Performance Task: Tusklessness in African Elephants

SCORING GUIDELINES UNIT 2

There are 9 possible points for this performance task.

Question 1

Sample Solutions Points Possible

(a) Frequency of Tusklessness in Females 3 points maximum

78 (tuskless females) 1 point for each correct
= 0.3 ×100 = 30%
260 (total female elephants) solution with work shown
Scoring note for parts (b)
(b) Frequency of Tusklessness in Males
and (c): Some students
27 (tuskless males)
= 0.1 × 100 = 10% who are more proficient in
270 (total male elephants) mathematics may quickly
see that 27 is 10% of 270 in
(c) Frequency of Tusklessness in Elephant Population
part (b) or that the average
105 (tuskless females + males)
= 0.2 × 100 = 20% of the two frequencies (30%
530 (total elephant population) and 10%) is 20% for part (c).
So, you may decide to award
these points without work
shown. However, it is always
a good habit for students
to show work so that they
make their thinking visible,
which can help prevent
them from making careless
computational errors.
Targeted Feedback for Student Responses

Some students may struggle to begin to set up this calculation. If so, provide the
hint that to find the frequency of tusklessness they first need to find the percentage
of female elephants that are tuskless in the entire population. You may even want to
help start the setup by providing the words instead of the numbers (i.e., frequency of
tusklessness in females = number of tuskless females/total number of females).

TEACHER NOTES AND REFLECTIONS

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 Practice Performance Task: Tusklessness in African Elephants

UNIT 2 Question 2

Sample Solutions Points Possible

Answers will vary. An example of a 3 points maximum

3-point answer is: 1 point for each appropriate sentence that
ƒ Tuskless males are more likely to uses evidence from the text or data table
survive than males with tusks because Scoring note: A student should not lose
poachers do not target tuskless males. a point for referencing an incorrect
ƒ The frequency of tusklessness in the calculation from Question 1 if their
total population is 20%, but reasoning is still appropriate. For example,
it is only 10% in the male population. if a student had incorrectly calculated 1%
ƒ Tuskless males have a hard time rather than 10%, in the example above,
mating, so the frequency of they should still get a point for the first
tusklessness in the male population is sentence.
lower than in the female population.

Targeted Feedback for Student Responses

Have students who do not provide appropriate evidence return to the text and
underline or highlight portions that may provide this type of evidence.

TEACHER NOTES AND REFLECTIONS

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 Practice Performance Task: Tusklessness in African Elephants

Question 3 UNIT 2

Sample Solutions Points Possible

ƒ Selective Pressure: Students should 3 points maximum

identify that poaching is a selective 1 point for appropriate use of the idea of
pressure for the African elephants that selective pressure
works against elephants with tusks.
1 point for appropriate use of the idea of
ƒ Variation: There are two different variation
forms of the trait—elephants with
1 point for appropriate use of the idea of
tusks and elephants born tuskless.
heritability
ƒ Heritability: Since more tuskless
elephants are surviving poaching
events, they are allowed opportunities
to reproduce and pass along the trait
of tusklessness to their offspring.
Therefore, over time, there may be
more tusklessness present in the
population.
Targeted Feedback for Student Responses

Students who only provide one or two of these concepts should return to the discussion
questions and final questions from the natural selection lab to find additional factors.

TEACHER NOTES AND REFLECTIONS

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 Key Concept EVO 3: Speciation

UNIT 2 LESSON 2.5

Launch Lesson – Introduction

AREA OF FOCUS
to the Process of Speciation—
ƒ Emphasis on Analytical
Salamander Evolution
Reading and Writing

OVERVIEW
SUGGESTED TIMING
~45 minutes
LESSON DESCRIPTION
Part 1: Introduction to the Ensatina
Salamanders of California HANDOUTS

Students watch and discuss a video clip ƒ 2.5.A: Introduction

that introduces the context and ideas about to the Ensatina
geographic mechanisms of adaptive divergence Salamanders of
for California salamanders in the genus Ensatina. California
ƒ 2.5.B: Further
Part 2: Further Investigation into Salamander
Investigation into
Evolution
Salamander Evolution
Students work in groups to examine further
research on the evolution of these salamanders
MATERIALS
and how reproductive isolation may also play a
role in keeping these subspecies distinct, even in ƒ LCD projector,
areas where interbreeding can occur. electronic whiteboard,
or other technology
Students then do a gallery walk to examine
for showing an online
and discuss peers’ ideas. Finally, a whole-class
video and image
discussion generates key ideas about the process
ƒ internet access to the
of speciation.
PBS Deep Look video
“Ensatina Salamanders
CONTENT FOCUS are Heading for a Family
In the lesson on Archaeopteryx for Key Concept EVO 1: Split” (4:38), at https://
Patterns of Evolution, students were introduced to how www.pbs.org/video/
scientists use shared morphological characteristics in ensatina-salamanders-
the fossil record to establish common ancestry. Now are-heading-for-a-
that students have gained a deeper understanding of family-split-miidxi/
the mechanisms that allow for adaptations and species’ ƒ materials to present
characteristics to change over time through natural group work: whiteboards
selection, they are ready to more deeply explore the or large poster paper,
process of speciation. This short investigation into neon dry-erase markers

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 Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

California salamanders of the genus Ensatina introduces students to ways in which UNIT 2
reduced gene flow can serve as a mechanism for speciation—in this case, in the form
of reproductive isolation due to geographic barriers. This lesson should be completed
before any formal discussion about speciation.

COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Speciation, extinction, and the abundance and distribution of organisms occur in

response to environmental conditions.

Learning Objectives Essential Knowledge

EVO 3.1(a) Explain how geographic EVO 3.1.1 Speciation occurs when
separation events can lead to the populations of the same species are
formation of new species. separated, resulting in reduced gene flow,
EVO 3.1(b) Describe mechanisms which over time allows populations to
that contribute to reproductive become genetically distinct from one
separation that could lead to another.
speciation. a. Geographic separation: a physical
barrier (e.g., rivers changing course, glacial
movement, continental drift).
b. Habitat specialization: niche
differentiation from others in the
population.
c. Behavioral separation: different mating
habits, times, or locations from others in the
population.
d. Mechanical separation: structural
differences in sex organs that make
individuals within a population unable to
reproduce with one another.

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 Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

UNIT 2 PART 1: INTRODUCTION TO THE ENSATINA SALAMANDERS

OF CALIFORNIA
Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution
The first part of this launch lesson introduces students to possible causes of speciation.
Unit 2: Evolution
It leverages students’ prior knowledge about how camouflage and mimicry may be
favored traits in some environments, as they may decrease selective pressure, and also
elicits prior knowledge of how different environments have varying pressures.
Introduction to the Ensatina Salamanders HANDOUT
2.5.A
First, call students’ attention to the driving questions and ideas for investigation
of California
found on Handout 2.5.A: Introduction to the Ensatina Salamanders of
AsCalifornia (also
you watch the shown
video, below).
keep in mindExplain that they
the following will consider
questions. Recordthese questions
any important
while
notes they
from thewatch
videoathat
video.
will help you answer these questions.

1. How did the subspecies adapt differently to their new environments as they
migrated south?

2. What selective pressures may have led to the survival of these new traits in the
salamanders?

3. What has caused the reduced gene flow between the subspecies?

Handout 2.5.A

ƒ Next, ask students to record their notes and observations as they watch the PBS Deep
Look video “Ensatina Salamanders are Heading for a Family Split” (https://www.pbs.
org/video/ensatina-salamanders-are-heading-for-a-family-split-miidxi/). Narration
introduces students to possible driving factors that, over time, may lead to speciation.

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 Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

ƒ After showing the video, lead a whole-class discussion that allows students to UNIT 2
share their notes and observations. While students should feel free to share any
of their observations, the main goal here is to work toward answering the three
driving questions. During the discussion, encourage students to recall prior
knowledge about pressures of predation that could lead to differential survival for
organisms that demonstrate camouflage or that mimic toxic prey. By the end of
this discussion, students should have an understanding of the answers to the three
questions:
u How did the subspecies adapt differently to their new environments as they
migrated south?
There were two migratory routes followed by the salamanders: one along the
Sierra Nevada mountain chain, where animals moved into the forest region; the
other along the coastal mountains. Along the forested route, the salamanders with
spots that helped them blend in survived. Along the coastal routes, salamanders
that mimicked the appearance of a dangerously poisonous newt from the region
were the ones that survived.
u What selective pressures may have led to the survival of these new traits in the
salamanders?
Predation pressures in the new forested and coastal environments differed from
pressures in the northern environment, so new traits were favored, such as large
spots for camouflage and bright colors for mimicry.
u What has caused the reduced gene flow between the subspecies?
The forested and coastal regions are physically separated by a large area known
as the Central Valley. This separation meant that salamanders from one region
did not have as much opportunity to mate with those from the other. Therefore,
the two populations of salamanders faced reduced gene flow due to geographic
barriers.

Guiding Student Thinking

This is a good opportunity to reinforce ideas of natural selection that students may
continue to struggle with. Remind students that these variations in subspecies
occurred over many generations (millions of years). During this time, individuals that
demonstrated genetic mutations allowing for better camouflage or warning mimicry
survived more often than individuals that did not. Their survival allowed for increased
chances of producing offspring with these same traits.

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 Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

UNIT 2 PART 2: FURTHER INVESTIGATION INTO SALAMANDER EVOLUTION

In this part of the lesson, students further investigate how the development of subspecies
of Ensatina salamanders advances our understanding of the process of speciation.

ƒ First, have students work in pairs or small groups

Meeting Learners’ Needs
to read the opening text and examine the map and
If your students have
table on Handout 2.5.B: Further Investigation difficulty with the opening
into Salamander Evolution. The text gives more text, you may want to have
insight into why these subspecies remain distinct, them take turns reading
even in areas that are not separated geographically. it aloud. This way, you
The map and table provide information about the can pause during the
salamanders’ range and morphology. You may reading to clarify any
potentially challenging
want to project images from the handout to help
words or phrases.
students see some of the details and colors.
ƒ After students have finished reading the opening
text and examining the table, have them use the Notes column in the table to
record their responses to the following questions:
u What are the three subspecies that demonstrate camouflage adaptations?
u What two subspecies along the coastal region demonstrate mimicry of toxic newts?
u What two species did Dr. Devitt study?
Having students respond to these basic text-dependent questions about the
salamanders is a good way to ensure they are aware of which subspecies are being
referred to in the text and their notes before beginning the higher-order thinking
questions on the handout.
ƒ Once you feel that all the student groups have a good
understanding of the context and various subspecies,
you can have them begin answering the set of four Classroom Ideas
questions on Handout 2.5.B. Remind them that During the gallery walk,
you might have one student
while they are doing this as a group and should
from each group stay
discuss and collaborate on ideas and answers, they
with their presentation to
should also record them individually on their own discuss it with classmates.
handouts so they have them after the lesson. You could also give
ƒ When students have completed the questions, allow these students a different
each group to present their answer to question 4 for colored marker to record
any revisions to their
other student groups to see—on small or medium
presentations that stem
whiteboards, on large poster paper, or written in from the gallery walk.
neon dry-erase marker on lab tables. Have students

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 Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

conduct a gallery walk of the group work and engage in peer-to-peer discussion as UNIT 2
they examine each other’s ideas. Students should make modifications to their own
ideas based on these discussions with their peers.

Instructional Rationale

The study of speciation is often complex, so it’s important not to present speciation
as occurring in “clean-cut” moments where we can easily deduce lineage-splitting
events. Therefore, this lesson purposefully focuses on a phenomenon, the California
salamanders, which allows an opportunity to discuss the natural processes that lead
to speciation without being definitive on whether speciation is occurring, or has
occurred, in these subgroups. This allows students to generate diverse and viable ideas
about speciation that will spark valuable peer-to-peer discussion.

ƒ Finally, lead a whole-class discussion that allows students to share their ideas
and answers to the four questions. For question 4, which was already discussed
during the gallery walk, record on the board a class list of conclusions about
speciation, and encourage students to highlight any new or conflicting ideas they
identified from their peers’ answers. Students should add to their own handouts
any conclusions not already recorded. Some sample responses for the questions are
provided on the next page.

EXTENDING THE LESSON

This launch task prepares students for deeper work examining speciation events
and exploring how those are modeled through the use of phylogenetic trees. The
following resources may be valuable as next-step lessons:
ƒ HHMI’s Lizard Evolution Virtual Lab (www.hhmi.org/biointeractive/lizard-
evolution-virtual-lab)
ƒ HHMI’s Sorting Finch Species: Click and Learn (www.hhmi.org/
biointeractive/sorting-finch-species)
ƒ Understanding Phylogenies from the University of California, Berkeley
(https://evolution.berkeley.edu/evolibrary/article/evo_05)

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Key Concept EVO 3: Speciation

Lesson 2.5: Launch Lesson – Introduction to the Process of Speciation—Salamander Evolution

UNIT 2
1. Typically hybrid offspring are not well adapted to their environment and are
therefore less likely to survive. Explain this statement.
Since hybrid offspring have a mix of characteristics from both subspecies, they don’t
blend in well nor do they fully mimic the toxic newt. Therefore, they will not reduce
predation pressure and will likely not survive. They are also less likely to find mates
and produce viable offspring.

2. Describe how Dr. Devitt’s research findings also contribute to our understanding
of why there continue to be distinct subspecies where the ring rejoins at the
southern tip of the Central Valley.
Devitt’s findings suggest there may also be a reproductive barrier since “eschscholtzii,
at least, has evolved suchLesson 2.5:females
that the Launch Lesson – Introduction
no longer recognizeto the Process
klauberi asofpotential
Speciation—Salamander Evolution

mates.” Therefore, there remains reduced gene flow between the subspecies on the Unit 2: Evolution
southern tip even though they live in the same area and do not face geographic
barriers.
3. Do you think the splitting of the Ensatina salamanders is an example of HANDOUT
2.5.B
speciation? Justify your answer.
Student answers will vary here. Since even scientists are split on this issue, this
allows for a diversity of viable answers. However, students should justify their
answers with appropriate evidence that discusses the ideas of being able to
interbreed, hybrids being less viable, and reduction of gene flow.
4. As a group, write at least three statements that describe how the development of
new species (speciation) can occur.
Sample responses:

• Speciation occurs when genetic changes result in two or more new species where
previously there had just been one species.

• Speciation occurs over many generations.

• In order for speciation to occur, there must be mechanisms of reduced gene flow.

• Physical barriers can result in reduced gene flow. Examples of barriers include
rivers, mountains, and large spaces between individuals (geographic isolation).

• Reproductive barriers can also reduce gene flow. Examples of reproductive

barriers include mating rituals, times, and locations.

Handout 2.5.B

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Performance Task

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 Performance Task: The Flashy Guppy Data Analysis

PERFORMANCE TASK UNIT 2

The Flashy Guppy Data Analysis

OVERVIEW

DESCRIPTION AREAS OF FOCUS

Students use their analytical reading skills to ƒ Emphasis on Analytical
extract information from a real-world study on Reading and Writing
the variance in guppy populations found in river ƒ Strategic Use of
ecosystems in Trinidad. Mathematics
This lesson is based on “Sex and the Single Guppy.” © 2010
by PBS. http://www.pbs.org/wgbh/evolution/sex/guppy/
low_bandwidth.html. SUGGESTED TIMING
~45 minutes
CONTENT FOCUS
Students demonstrate their understanding of the HANDOUT
factors of inheritance, differential reproduction, and ƒ Unit 2 Performance
selective pressures in unique environments. They Task: The Flashy Guppy
utilize their knowledge of these factors to describe how Data Analysis
natural selection influences phenotype frequency in a
population.
MATERIALS
The following materials
are optional:
ƒ calculator
ƒ ruler
ƒ colored pencils

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2 COURSE FRAMEWORK CONNECTIONS

Enduring Understandings

ƒ Biological evolution is observable as phenotypic changes in a population over

multiple successive generations.

Learning Objectives Essential Knowledge

EVO 2.2(a) Describe how selective EVO 2.2.1 Darwin’s theory of natural
pressures in the environment can affect selection is that a selective mechanism
an organism’s fitness. in biological evolution may lead to
EVO 2.2(b) Explain how selective adaptations.
pressures in the environment could a. Abiotic ecosystem components
cause shifts in phenotypic and/or allele (e.g., nutrients) and biotic ecosystem
frequencies. components (e.g., predators) act as
EVO 2.2(c) Use data to describe how selective pressures.
changes in the environment affect b. Favorable traits in a given environment
phenotypes in a population. lead to differential reproductive success, or
EVO 2.2(d) Predict how allelic fitness, and over time can produce changes
frequencies in a population shift in in phenotypic and/ or allele frequencies.
response to a change in the environment. c. Heritable traits that increase an
organism’s fitness are called adaptations.
d. Over time, the relative frequency of
adaptations in a population’s gene pool can
increase.
e. Patterns of natural selection can include
phenomena such as coevolution, artificial
selection, and sexual selection.
EVO 2.2.2 Favorable traits are relative to
their environment and subject to change.
a. Changes in the environment happen
both naturally (e.g., floods, fires, climate
change) and through human-induced
activities (e.g., pollution, habitat
destruction, climate change).

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 Performance Task: The Flashy Guppy Data Analysis

SUPPORTING STUDENTS UNIT 2

BEFORE THE TASK

ƒ Since there is an extended text used to introduce this performance task, remind
students of the effective reading strategies they can use to annotate and extract
information and highlight key ideas.
ƒ If timing is an issue for completing this performance task, you may want to ask
students to do the reading and annotation of the introductory text at home the
night before.
DURING THE TASK
Support students in successfully completing this performance task by doing the
following:

ƒ Some students may need additional support in accessing the text in this
performance task. If so, you may want students to work collaboratively in pairs to
annotate the text and share key ideas. You may also want to chunk the reading for
students and have a short debrief on it as a whole class prior to them engaging in
the performance task questions.
ƒ To aid students in viewing details and/or color of images on the handout, use an
LCD projector or electronic whiteboard to display the images for the class.
ƒ Since there is a lot of data to analyze in this performance task, students are
provided reflection questions after each data set. These are not intended to be
scored, since concepts associated with these questions are assessed later in Part 2.
However, you may want to encourage students to use their ideas captured in these
reflection questions in order to provide more coherent final answers in the scored
Part 2 portions.

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2 SCORING GUIDELINES

There are 26 possible points for this performance task.

Part 1: Data Analysis (10 points maximum)

Sites 1–3

Sample Solutions Points Possible

Site 1 Site 1 Solutions: 2 points maximum

Drab = 12% Site 2 Solutions: 4 points maximum
Drabbest = 81% Site 3 Solutions: 4 points maximum
100%
0.5 point for correct percentage of
90%
population in table
Percent of total population

80%
(relative frequency)

70% 0.5 point for correct percentage of

60% population on graph
50%
40%
30%
20%
10%
t

ht

t
es

es
ra
ig
ht

bb
D
Br
ig

ra
Br

Color

Site 2
Brightest = 86%
Bright = 8%
Drab = 2%
Drabbest = 4%
100%
90%
Percent of total population

80%
(relative frequency)

70%
60%
50%
40%
30%
20%
10%
t

ht

st
es

ra

be
ig
ht

D
Br

b
ig

ra
Br

Color

Continues on next page.

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 Performance Task: The Flashy Guppy Data Analysis

Site 3 UNIT 2

Brightest = 1%
Bright = 45%
Drab = 51%
Drabbest = 3%
100%
90%
Percent of total population

80%
(relative frequency)

70%
60%
50%
40%
30%
20%
10%
t

ht

t
es

es
ra
ig
ht

bb
D
Br
ig

ra
Br

Color

Targeted Feedback for Student Responses

If students struggle with their calculations for frequency, it would be good to have them
return to question 1 of the practice performance task on tuskless elephants. You can
also first provide additional hints that frequency is a ratio or percentage, e.g., number
of bright guppies/total guppies, and then have students complete the data analysis.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2 Part 2: Drawing Conclusions (16 points maximum)

Question 1

Sample Solutions Points Possible

Explanation: Shifts in phenotype frequencies 2 points maximum

in populations due to natural selection take 1 point for explanation
many generations to occur.
1 point for use of data
Data: He collected data after at least 220
Scoring note: Students may select any
weeks (over 4 years) or 9 generations. This
of the experimental sites to reference
allowed enough time to see if selective forces
the length of time that the data were
were influencing the guppy’s phenotype
collected to support their explanation.
frequencies.

Targeted Feedback for Student Responses

Students often struggle with understanding how long it may take to see changes in
populations. If they don’t provide data to support their answers, point students to
comparing the number of generations across the three sites and encourage them to
then think about their answer based on how long the study lasted.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: The Flashy Guppy Data Analysis

Question 2 UNIT 2

Sample Solutions Points Possible

(a) Sample answer: The surrounding 2 points maximum

environment (e.g., sand, rocks, (a) 1 point for environmental pressures
submerged vegetation) may vary in for camouflage
different areas of the stream and so
(b) 1 point for one way the selective
coloration will vary, helping the guppies
pressures change the guppy’s fitness
better blend in and avoid predation.
(b) Sample answer 1: The new environment
may have fewer predators, and therefore
camouflage would offer less of a benefit.
Sample answer 2: The new environment
may have a different substrate (such as
rocks instead of sand) and the guppy’s
coloration would be less effective for
camouflage.
Targeted Feedback for Student Responses

If students have trouble generating valid selective pressures, have them return to
the opening text that provided background information on the habitat and predator
population that guppies face in rivers. This should help students generate some better
ideas about what advantages guppies could possess to increase their survival and/or
reproduction chances.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2 Question 3

Sample Solutions Points Possible

Claim 1: Refute 6 points

maximum
Evidence Reasoning
(3 pts per claim)
Experimental site 2 is a Since predation risk in shallow pools 1 point for
shallow pool with only is low, the greatest pressure on the correctly
one kind of predator. males is to mate (sexual selection). supporting or
The most abundant The brightest males mate more often refuting each
trait in the site 2 and therefore continue to pass on claim
population was the that gene to new male offspring in 1 point for
brightest coloration. the next generation. That is why after appropriate
This represented many generations, they make up evidence
86% of the guppy the largest percentage of the guppy
1 point for
population. population.
appropriate
Claim 2: Support reasoning

Evidence Reasoning

Experimental site 1 is a In this part of the river, the greatest

deep pool with numerous pressure on the males is predation.
predators so predation The brightest males are most likely
pressure is high. The getting eaten and therefore do
most abundant trait in the not produce many offspring that
population in site 1 was would contribute these genes to
the drabbest coloration, the next generation. However, the
seen in 81% of the male drabbest males are more likely to
guppy population. There survive to pass along their genes,
were very few of the which is why they make up the
brightest males in the largest percentage of the guppy
population, at only 2%. population.

Targeted Feedback for Student Responses

Some students may struggle with coordinating both the evidence and reasoning for
whether they feel the claim should be refuted or supported. In these cases, help them
return to the guiding questions for each experimental site and have them work with a
partner to compare their data analysis and conclusions about selective pressures.

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2
TEACHER NOTES AND REFLECTIONS

Question 4

Sample Solutions Points Possible

Claim: When predation pressure is moderate, the 3 points maximum

two intermediate groups, bright and drab, are most 1 point for crafting an
successful. appropriate claim
Evidence Reasoning 1 point for appropriate
evidence used to support
In experimental site 3, Since this site contains the claim
there was a moderate a moderate number of 1 point for appropriate
amount of predation. predators, the pressures reasoning to support
The bright and the on both predation and evidence and claim
drab guppies were mating are relatively
Scoring note: There are
most abundant. Bright equal. Therefore, the two
many appropriate claims
made up 45% of the intermediate phenotypes
that students may craft
population, and drab (bright and drab) were
from the data provided.
made up 51% of the more abundant as the
The one at left is just one
population. brightest males were
illustrative example.
most likely to be eaten
more but also mated
more often, whereas the
drabbest males mated
less but were also likely
to be eaten less often.

Targeted Feedback for Student Responses

Similar to question 3, some students may struggle with writing an appropriate claim,
and coordinating both the evidence and reasoning to support that claim. In these cases,
help students return to the guiding questions for that experimental site and have them
work with a partner to compare their data analysis, claims, evidence, and reasoning
about that site.

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 Performance Task: The Flashy Guppy Data Analysis

UNIT 2
TEACHER NOTES AND REFLECTIONS

Question 5

Sample Solutions Points Possible

ƒ Students should indicate that they would 3 points maximum

need evidence that the color traits are 1 point for heritability
heritable.
1 point for selection
ƒ Students need to discuss that while they
1 point for reproduction
did see evidence for selection here based
on predation, they would need more
trials.
ƒ Students should want to collect more
information about reproductive rates
across the many color variants to ensure
differential reproduction.

Targeted Feedback for Student Responses

This is really the capstone understanding of the factors that influence frequency shifts
of phenotypes in populations through natural selection. So if students struggle to
provide all three factors, encourage them to return to Lesson 2.4: Modeling Natural
Selection Lab or the practice performance task for this unit to review these factors and
provide appropriate descriptions of each one.

TEACHER NOTES AND REFLECTIONS

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

The Flashy Guppy Data Analysis PERFORMANCE

TASK

Read the following information, then complete Parts 1 and 2.

INTRODUCTION: THE FLASHY GUPPY

A properly dressed male guppy, with its bright blue spots and brilliant splashes of
orange, can’t help but stand out. But for a fish that spends its life swimming among
predators, it seems that good camouflage would have a big advantage over colors that
attract attention. If flashiness is a liability, why do we still see this trait in the population?
ENDLER’S RESEARCH
When evolutionary biologist John Endler began studying Trinidad’s wild guppies in
the 1970s, he was struck by the wide variation among guppies from different streams,
even among guppies living in different parts of the same stream. Males from one
pool sported vivid blue and orange splotches along their sides, while those farther
downstream carried only modest dots of color near their tails. Endler also observed
differences in the distribution of guppy predators, and in the color and size of gravel in
different stream locations.

Endler photographed hundreds of guppies and carefully collected data about their size,
color, and the size and placement of their spots. He began to see a strong correlation
between where guppies lived in a particular stream and whether the fish were bright
or drab. But what was responsible for these trends in coloration? And if bright colors
made guppies more conspicuous to predators, why should males be colorful at all? To
find out, Endler formed a hypothesis based on his observations, and then set out to test
it. His results proved to be one of evolutionary biology’s most important discoveries.
GUPPY HABITAT TYPES
Guppies usually occupy the entire length of Trinidad’s Aripo River, and often so do
their predators, such as pike cichlids, blue acara, and rivulus. However, different
sections of the river offer unique environmental characteristics and pressures that may
influence the color variation seen in the guppies (see the table on the next page).

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

PERFORMANCE RIVER SECTION POPULATIONS

TASK

Deep Pool Pool Behind Natural Dam Shallow Pool

Description Deep section Pool formed by a low- Shallow area along

along the lying rock dam; the dam the waterway, where
waterway limits upstream movement only small fish can
of some of the largest live
predators

Population ƒ Guppies ƒ Guppies ƒ Guppies

ƒ A variety of ƒ Some predators (no ƒ Smallest and
predators large ones) least effective
predators

Predation High Moderate Low

Risk

SPECIES INFORMATION
Guppies collected during the experiment were classified into four color variants:
brightest, bright, drab, and drabbest. Endler was interested in studying whether the
pressures for mating and predation influenced the frequency of the color variations
found in different populations along the river. The table shown provides information
about the guppies Endler studied and their predators.

PREDATORS AND PREY IN ENDLER’S STUDY

Description Images

Common name: Pike cichlid

Scientific name: Crenicichla alta
Size: Up to 12 in. (approximately 30 cm)

Common name: Blue acara

Scientific name: Aequidens pulcher
Predators Size: Up to 7 in. (approximately 18 cm)

Common name: Rivulus

Scientific name: Rivulus hartii
Size: Up to 5 in. (approximately 12.5 cm)

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

PERFORMANCE
Common name: Guppy or millions fish TASK
Scientific name: Poecilia reticulata Brightest

Sex of individuals in study: Male

Size: 1.4 in. (approximately 3.5 cm)
Prey Color variations in population:
Brightest Drabbest

Bright
Drab
ƒ Drabbest

Text and data above are excerpted and adapted from “Sex and the Single Guppy.” © 2010 by PBS. http://
www.pbs.org/wgbh/evolution/sex/guppy/low_bandwidth.html.

PART 1: ANALYZING DATA

The data sets shown are representative of findings from Endler’s research.
Examine the data and complete the tables and graphs.

Experimental Site 1 Information

River Site: Deep pool
Number and Type of Predators: 30 rivulus, 30 blue acara, 30 pike cichlid
Guppy Total Population: 210
Number of Generations: 10
Number of Weeks: 286
Data Collected Data Analysis
100%
Brightest Bright Drab Drabbest 90%
Percent of total population

80%
Number of
(relative frequency)

4 11 25 170 70%
Guppies 60%

Percent of 50%
40%
Population 2% 5% 30%
(rounded)
20%
10%
t

ht

t
es

es
ra
ig
ht

bb
D
Br
ig

ra
Br

Color

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

PERFORMANCE
REFLECTION QUESTIONS
TASK
1. Which type of guppy is most successful in this environment?

2. Why do you think this is the case? What is the advantage of this common
phenotype in this environment?

Experimental Site 2 Information

River Site: Shallow pool
Number and Type of Predators: 30 rivulus
Guppy Total Population: 236
Number of Generations: 10
Number of Weeks: 265
Data Collected Data Analysis
100%
Brightest Bright Drab Drabbest 90%
Percent of total population

80%
Number of
(relative frequency)

204 18 5 9 70%
Guppies 60%

Percent of 50%
40%
Population
30%
(rounded)
20%
10%
t

ht

t
es

es
ra
ig
ht

bb
D
Br
ig

ra
Br

Color

REFLECTION QUESTIONS

1. Which type of guppy is most successful in this environment?

2. Why do you think this is the case? What is the advantage of this common
phenotype in this environment?

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

3. How does this result differ from Site 1? If the results are different, provide some PERFORMANCE
TASK
reasoning as to why.

Experimental Site 3 Information

River Site: Pool behind natural dam
Number and Type of Predators: 30 pike cichlid, 30 blue acara
Guppy Total Population: 218
Number of Generations: 9
Number of Weeks: 220
Data Collected Data Analysis
100%
Brightest Bright Drab Drabbest 90%

Percent of total population

80%
Number of

(relative frequency)
2 98 111 7 70%
Guppies 60%

Percent of 50%
40%
Population
30%
(rounded)
20%
10%
t

ht

t
es

es
ra
ig
ht

bb
D
Br
ig

ra
Br

D
Color

REFLECTION QUESTIONS

1. Which type of guppy is most successful in this environment?

2. Why do you think this is the case? What is the advantage of this common
phenotype in this environment?

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

PERFORMANCE 3. How does this result differ from Sites 1 and 2? If the results are different, provide
TASK
some reasoning as to why.

PART 2: DRAWING CONCLUSIONS

1. For each of the three experimental sites, examine the number of weeks that the
study lasted. Explain why you think Endler waited this length of time to collect
data. Use one or more of the data sets to help illustrate your explanation.

2. Endler also noticed that even the colors in the drabbest male guppies varied from
one another in different areas of the river.
(a) What could be a cause for this difference in coloration?

(b) If a drabbest male was moved from one area of the river to a new area, how
might the selective pressures change the guppy’s fitness?

3. Analyze the two claims made on the next page. For each one, decide whether the
information provided in the reading and data sets supports or refutes that claim.
Then provide evidence and reasoning to support your decision.

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

Claim 1: When very few predators are present, the most fit color variation is the PERFORMANCE
TASK
drabbest male.

Support or Refute?

Evidence
Reasoning
(from reading and/or data sets)

Claim 2: When many predators are present, the most fit color variation is the
drabbest male.

Support or Refute?

Evidence
Reasoning
(from reading and/or data sets)

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 Performance Task: The Flashy Guppy Data Analysis

Unit 2: Evolution

PERFORMANCE 4. Using the background information and data sets, craft another claim about what
TASK
occurs when there are moderate numbers of predators in the environment. Be
sure to support your claim by using the evidence provided. Justify your claim and
evidence with reasoning about natural selection principles.

Claim:

Evidence
Reasoning
(from reading and/or data sets)

5. Conclusion: Make a claim about whether natural selection is acting on the color
variations in guppies. Use evidence from the background reading and data sets
and reasoning to support your claim. If there is a line of evidence that is missing
but necessary for your claim to be supported, identify it.

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