Unit I Student Guide

Table of Contents

1. The Scientific Method........................................................................................ 2

2. Introduction to Ecology ..................................................................................... 3
3. Ecosystems Have Living and Nonliving
Components ...........................................4 4. Energy and Chemicals Flow within
Ecosystems ..................................................4 5. Energy Pyramids Reveal the
Inefficiency of Food Chains ......................................6 Collaborative Catch-up:
Food Chains ....................................................................7 6. Energy Flows from
the Sun and through All Life on Earth ......................................8 Collaborative
Catch-up: Photosynthesis................................................................ 9 7. Living
Organisms Extract Energy through Cellular Respiration ............................ 10 8.
Human Impact on Ecosystems and Food Webs: Modern Agriculture .................. 11
Collaborative Catch-Up: Bioaccumulation........................................................... 13
9. Human Impact on the Biosphere: Fossil Fuels and the Carbon Cycle..................
14 10. How Does Coal/Gas Create Electricity?..........................................................
15 11. Human Impact on the Biosphere: Climate
Change .......................................... 15 12. Greenhouse Effect and Climate Change
......................................................... 17 13. Global CO2
levels ......................................................................................... 19 Collaborative
Catch-up: Sources of CO2 emissions.............................................. 20 14.
Alternative Energy Sources ............................................................................ 25 15.
Methods to Reduce CO2 Emissions and Slow Climate Change......................... 25
16. Natural Resources ........................................................................................ 26
Collaborative Catch-up: Renewable versus Nonrenewable Resources...................
27 17. Human Impact on the Biosphere: Ecological
Footprints................................... 28 Collaborative Catch-up: Ecological
Footprints ..................................................... 29 18. Population Ecology and
Growth: .................................................................... 29 19. Assessing Growth Rate
in a Population........................................................... 31 Collaborative Catch-up:
Fertility Rate and Population Growth ............................... 31 20. Age Pyramids
Reveal Much About a Population ............................................... 32 Extra Credit
(optional) Assignment (5 points): Population Growth........................... 33
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Unit I Student Guide
Ecology and Human Impacts on the Biosphere
1. The Scientific Method
a. Although some people envision scientists in labs checking off the steps
of the scientific method as they work, in reality the scientific method
is a highly flexible process that can be used to explore a wide variety of
thoughts, events, or phenomena. We refer to this process as scientific
thinking. A basic element of scientific thinking includes the scientific
method.
b. The first step of science is making observations about the world.

i. Observations involve looking for interesting patterns or cause-

and effect relationships.
c. The second step is to create a tentative explanation for
observed phenomena. This is called a
___________________.

i. Useful hypotheses involve testable predictions. Hypotheses can

be refined and adjusted as needed.
d. The third step is to design and experiment that will test the hypothesis

i. Experimental design is a critical part of the scientific process.

Experiments that are carefully and purposefully designed are
most likely to show cause-and-effect relationships between
variables. Additionally, it is critical that experimental results can
be
reproduced when the experiment is repeated.

ii. Controlling variables makes experiments more powerful

iii. Define each of the following elements of experiments:

● Experimental group

● Control group

● Variables

○ Independent variable

○ Dependent variable

● Why is it important to control variables in an experiment?

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e. Drawing conclusions from experimentation provides opportunity for
revision and peer review. In your own words, explain why it is important
to include revision in this process.

2. Introduction to Ecology
a. What is Biology?
i. ____________ is the science that defines life.
ii. Many branches of biology exist
iii. Examples:

b. Ecology is the study of how organisms interact with each other and
their ______________________.
c. Ecology includes the study of individuals, populations, communities,
ecosystems, and the ___________________.
d. Levels of Ecological Organization
i. Individual
● A single organism.
● Example: A single ___________ in a forest.
ii. Population
● A group of individuals of the same species living in the
same area.
● Example: A population of _____________ in a pond.
iii. Community:
● All the populations of different species that live and
interact in an area.
● Example: The community of plants, animals, and
microorganisms in a ________________.
iv. Ecosystem:
● A community of living organisms and their nonliving
environment.

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 ● Example: A coral reef ecosystem includes fish, coral,
water, and ________________.
v. Biosphere:
● The global sum of all ecosystems.
● Example: The entire planet Earth as a living
_________________.

3. Ecosystems Have Living and Nonliving Components

a. Ecosystems can be of various sizes involving all different living
organisms. b. What are the two specific features necessary to construct an
ecosystem? i. Living components (biotic)

● Examples: cat , bacteria, human , trees , contain DNA

require energy

ii. Non-living components (abiotic)

● Examples: electronic devices , rocks , virus, sunlight ,

cloud, water, temperature. fireb

4. Energy and Chemicals Flow within Ecosystems

a. The flow or pathway that energy takes in an ecosystem reflects
important characteristics of that particular ecosystem. Regardless of the
type of ecosystem, the energy to support all life comes from the
___________.

b. Solar energy undergoes many transformations as it passes through

an ecosystem. The various levels are referred to as ____________
levels.

c. Food Chains: Define each level of energy flow and give an

example. i. Producers:

ii. Primary consumers:

● A primary consumer is also called a ___herbivores_____________.

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iii. Secondary consumers:

● A secondary consumer is also called a

___carnivores omnivores_______________.

iv. Tertiary consumers:

Top cartnivores animals taht eat teh animals tahts eat the animals tahts
east plants for example tiger eagles.

v. Higher level consumers: quaternary consumer feed on tertiary

consumers

vi. Consumers that feed on both plants and animals are

called _______________________.

vii. What is the role of a detritivore in the food chain? Give an

example of this organism. We must recycle, anything that died
in the food chain those members is going to make thor way to

viii. What is the role of a decomposer in the food chain? Give

an example of this type of organism.
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d. What is the difference between food chains and food webs?
i. A food web is a complex network of interconnected food chains
showing the multiple pathways through which energy and
nutrients flow in an ecosystem.
ii. Food webs illustrate the complexity and interdependence of
organisms within an ecosystem.
iii. They help show the impact of changes in one part of the
ecosystem on the __________________.
● Example: Grass is eaten by both grasshoppers and
rabbits; grasshoppers are eaten by frogs and birds;
rabbits are eaten by foxes and _____________.

5. Energy Pyramids Reveal the Inefficiency of Food Chains

a. Living organisms, including carnivores and herbivores, can convert
only ___10______ % of what they consume into their own mass.
i. The remaining _____% is diverted to what?

b. In understanding the flow of energy in an ecosystem, it is important

to define the biomass of the given area. What does biomass refer
to?

c. The relative shape of the pyramid can also vary depending on the
ecosystem. Do the producers or do the top consumers impact the
shape of the pyramid more? Why?
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Figure 1-1. Trophic Pyramid1

Collaborative Catch-up: Food Chains

Using the table below, explain why meat can be considered a “luxury” when
viewed in terms of energy.

Figure 1-2. Feed Conversion Graph2

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Image Attribution
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6. Energy Flows from the Sun and through All Life on Earth
a. Photosynthesis uses energy from sunlight to make food
i. The big picture overview of photosynthesis is presented in the
 figure below.

Figure 1-3. Illustration of Photosynthesis3

ii. Three inputs are needed for photosynthesis to occur. Explain

where each of these inputs comes from and what it will be used for
in
photosynthesis:

● Light energy:

● Water:

● Carbon dioxide:

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iii. There are two outputs produced during photosynthesis. Explain
how each is created during photosynthesis and what will happen
to each.
 ● Sugar:

● Oxygen:

b. Describe the significance of photosynthesis:

c. Photosynthesis takes place in plant cell organelles called chloroplasts.

d. How can you tell which parts of a plant are photosynthesizing? What is the
name of the pigment required to capture sunlight energy?

e. The organelle that houses chlorophyll and where photosynthesis takes place
is the __________________________.
f. Write the complete equation for photosynthesis below:

Collaborative Catch-up: Photosynthesis

Complete the following statements.

1. Deciduous trees are trees that lose their leaves in the fall. Chlorophyll production
in deciduous trees __decrease___ in the fall.
2. What does the loss of leaves mean to the level of photosynthesis in areas where
this happens?

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7. Living Organisms Extract Energy through Cellular Respiration
a. How do living organisms fuel their actions? - Cellular
Respiration i. What sorts of organisms perform cellular
 respiration?

ii. Why do organisms perform cellular respiration?

b. Where does cellular respiration take place?

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c. What are the major inputs and outputs of cellular respiration? Write the
equation below the diagram below.
 Figure 1-4. Illustration of Cellular Respiration4

d. Where does the CO2 that you are exhaling right now come from? Be specific
with your answer.

e. The CO2 you are exhaling will soon be utilized by plants. What will the
plants ultimately do with the CO2?

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f. Approximately _____ ATP molecules can be produced through
cellular respiration from a single molecule of glucose.

8. Human Impact on Ecosystems and Food Webs: Modern Agriculture

a. Modern farming is unsustainable for the environment. It was designed
to increase production but does not consider the health of the
environment.
b. Unsustainable agricultural practices include:
i. Industrial sprinkler irrigation
ii. Use of inorganic pesticides
iii. Monoculture

● Multiple fields that grow a single crop

c. Impact of industrial agriculture on the local ecosystems and

resources i. Loss of biodiversity
ii. Overuse of natural resources
● Water: Industrial irrigation
○ What is a more sustainable approach to sprinkler irrigation?

● Soil: Repeated monoculture on the same fields

○ What is a more sustainable approach to repeated
monoculture of fields?

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iii. Loss of beneficial populations
● Pesticide use
● Use of pesticides can damage important populations
○ Example:
 ● What is a more sustainable approach to the use of industrial
pesticides?

iv. Bioaccumulation
● Bioaccumulation is the buildup of toxic substances in the tissues
of organisms over ________.
● Process of Bioaccumulation:
○ Introduction: Toxic substances enter the environment through
pollution.
i. Example: Pesticides, heavy metals, and ________.
○ Absorption: Organisms absorb toxins from their environment
or food.
i. Example: Fish absorbing mercury from ________.
○ Concentration: Toxins accumulate in higher concentrations in
higher trophic levels.
i. Example: Predators accumulating higher toxin levels
from their prey.
● Effects of Bioaccumulation:
○ Health problems in wildlife and humans.
○ Disruption of ecosystems and loss of ____________.

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Collaborative Catch-Up: Bioaccumulation
Start with a lower trophic level organism (e.g., phytoplankton) and draw a diagram
showing how toxins accumulate as they move up the food chain to higher trophic levels
(e.g., fish, birds, humans). Include arrows to show the direction of toxin movement and
accumulation.
 1. Why do toxins accumulate more in higher trophic levels?

2. What are the potential impacts of bioaccumulation on wildlife and humans?

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9. Human Impact on the Biosphere: Fossil Fuels and the Carbon Cycle
a. Carbon Cycle: An example of nutrient cycling
i. As with all nutrients, carbon must be recycled (the ecosystem is
CLOSED in terms of nutrients)
● Carbon cycle includes both fast and slow pathways
Fast pathway:

Slow pathway:

b. How does carbon move from the fast pathway to the slow pathway?
 c. Carbon Cycle: Slow Pathway
i. Where is carbon stored in the slow pathway?

d. Fossil fuels are formed when plants and animals are not
completely decomposed
i. The remnants are converted into coal, oil, natural gas, or rock (such
as limestone)
● Carbon returned to the atmosphere naturally returns to the fast
pathway very slowly.
e. Coal - The world’s most abundant fossil fuel

i. Coal - organic matter (woody plant material) that was compressed

under very high pressure to form dense, solid carbon structures

ii. Dirtiest fossil fuel: CO2 emissions and other contaminants

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f. Humans severely impacting the carbon cycle
i. Burning fossil fuels moves carbon from the ground to the air
● What impact does this have?

ii. Cutting forests and burning fields (deforestation)

● What impact does this have?

g. Today’s atmospheric carbon dioxide reservoir is the largest in the past

650,000 years
i. The driving force behind climate change

10. How Does Coal/Gas Create Electricity?

a. Coal is burned to create heat. That heat is used to turn water into high
pressure steam that is used to turn a turbine which in turn, turns a generator
that creates an electrical current.
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Figure 1-5. Illustration of Electricity Generation from Coal5 5Image attribution
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11. Human Impact on the Biosphere: Climate Change
a. Climate change refers to significant changes in global temperatures
and weather patterns over ________.
b. Human activities can damage the environment
i. The release of greenhouse gasses influences the global climate.
c. The average temperature on earth has increased rapidly over the past 50 years.
d. Causes of climate change
i. Greenhouse gasses
● Increased levels of CO2, methane (CH4), and nitrous oxide
(N2O) trap heat in the atmosphere.
● These gasses are naturally occurring and good insulators –
necessary to buffer the temperature of earth’s surface to support
life
○ CO2 (Carbon Dioxide)
i. 82% of greenhouse gasses
ii. Where does this come from?
● CH4 (Methane)
○ 9% of greenhouse gasses
○ Much more potent an insulator
○ Industry and agriculture (cattle ranching)
○ Where does this come from?

ii. Deforestation

● Reduces the Earth's capacity to absorb CO2.

● Example: Clearing forests for agriculture and ___________.

iii. Industrial Activities

● Release of pollutants and greenhouse gasses.

● Example: Manufacturing processes and energy ________.

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12. Greenhouse Effect and Climate Change
a. The “Greenhouse Effect”
i. The greenhouse effect is the retention of heat in the atmosphere due
to the insulating effects of greenhouse gasses.
ii. The consequence of the greenhouse effect is a warming planet -
global warming. This is the underlying cause of climate change

Figure 1-6. Greenhouse Effect6

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b. Climate change
 i. Effects of climate change can be varied
● Sea level rise
● Change in weather patterns
● Changes in migration patterns
● Arctic ice is thinning and melting.
● Infectious diseases may change/expand ranges.

ii. Discuss some specific examples of these effects

iii. How do we address Climate Change?

● Global climate change is difficult to tackle because it is extremely
large in scope.
● Efforts to fight global climate change include:
○ Reducing fossil fuel consumption
○ Reducing deforestation and replanting forests
○ Increasing energy efficiency of our homes and cars
● Discuss some specific examples of these methods to
address/mitigate climate change.

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13. Global CO2 levels
a. Global CO2 levels have increased over time.
b. Modern Data:

Figure 1-7. Global

CO2 levels 1980 to present7

c. In the past 55 years, CO2 levels have risen from _____________ to ________ppm.

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Image Attribution
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Collaborative Catch-up: Sources of CO2 emissions
Using the charts/images/graphs below, answer the following
questions. 1. What economic sector contributes the most to US CO2
emissions?

2. Which sector is second in emissions?

Figure 1-8. Infographic of U.S. Greenhouse GAs Emissions8

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Chart Attribution

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Transportation and CO2 emissions.
 3. What is the greatest source of transportation-based CO2 emissions in the US?

Figure 1-9. Transportation-Related CO2 Emissions9

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Chart Attribution

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Electrical Generation and CO2 emissions.
 Figure 1-10. U.S. Electrical Generation and CO2 Emissions10
4. How is most of our electricity produced?

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Chart Attribution

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 Figure 1-11. U.S. Greenhouse Emissions by Economic Sector11

5. Circle one: Has US greenhouse gas emissions decreased/increased/stayed the

same? 6. In what area have emissions decreased the most?

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Chart Attribution

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 Figure 1-12. Global Greenhouse Emissions12

7. Looking at countries around the world, which countries are seeing a rise in
carbon emissions?

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Chart Attribution

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14. Alternative Energy Sources
a. Solar energy - light energy and radiant heat energy from the sun converted
to electrical energy
 b. Wind power
i. fastest growing energy sector
ii. estimated that wind generation could produce about 40% of the
country's present energy needs
c. Hydroelectric power - uses the kinetic energy of moving water to turn
turbines and generate electricity
d. Nuclear Power

15. Methods to Reduce CO2 Emissions and Slow Climate Change

a. Energy Efficiency
i. Energy efficient light bulbs and appliances
● An energy-saving light bulb (Compact Fluorescent Light) uses
approximately 1/4 of the energy consumed by an incandescent
bulb.
● Use energy labels to look at appliances and energy efficiency.

Figure 1-13. Energy Guide Label13

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Image Attribution

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b. Insulating homes and businesses
c. Mitigating deforestation
i. A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year 14
16. Natural Resources
a. Renewable resources
i. Resources that can be ______________ naturally at a rate
comparable to their consumption.
ii. Examples: Solar energy, wind energy, ________, and ________.
b. Nonrenewable resources
i. Resources that exist in finite amounts and cannot be ____________
at a rate that matches their consumption.
ii. Examples: Fossil fuels (coal, oil, natural gas), ________, and ________.
Table 1-1: Natural Resources Comparison Table

Resource Type Renewability Examples Environmental

Impact

Renewable Can be replenished Solar, Wind, Lower, if

Biomass managed
properly

Nonrenewable Finite Coal, Oil, Higher, due to

Natural Gas extraction and
pollution

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Collaborative Catch-up: Renewable versus Nonrenewable Resources Below

is a chart that lists several natural resources. In your group, complete the chart.

Table 1-2: Renewable versus Nonrenewable Resources

Resources Renewable or Advantages of Disadvantages of

Nonrenewable this resources this resource

Solar energy

Coal
 Wind energy

Natural gas

Hydroelectric power

Petroleum

Nuclear energy

Geothermal
energy

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17.Human Impact on the Biosphere: Ecological Footprints
a. Ecological footprints express the environmental impact of an individual or
a population in terms of the cumulative amount of land, water, and
resources required to provide the raw materials consumed, and recycle
the waste produced by their lifestyle.
 Figure 1-14. Ecological Footprints15

b. Ecosystem services - Resources and natural processes supplied by

natural ecosystems
i. Utilized by human populations and industries
ii. Nutrient recycling, fresh water, food, recreation, lumber, sewage
treatment, etc.

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Image Attribution

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Collaborative Catch-up: Ecological Footprints
What can you do right now for $10.00 or less to reduce your ecological footprint?
(Think of 2 things that you can do that might decrease your use of natural resources,
production of waste, and electricity.)

1.
 2.

18. Population Ecology and Growth:

a. Environmental resistance factors
i. Conditions and resources that affect the ecology and growth of
populations/communities are:
● Density dependent factors: affect a population as the population
increases (increases density)
○ Examples:

● Density independent factors: natural or human-caused

environmental calamities. These are not based on the population
size.
○ Examples:

b. Exponential growth:
i. A population’s size increases rapidly due to unrestricted growth
ii. “J curve”
iii. This growth is eventually limited due a limiting factor
c. Logistic growth
i. Population growth that has stabilized because of resource limitations
ii. As density increases, a population reaches the carrying capacity of
its environment, and limited resources put a ceiling on growth.
iii. Forms an S-shaped curve when graphed

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 Figure 1-15. Logistic versus Exponential Growth16
d. Carrying Capacity is the number of individuals of a population that
the environment can support (or carry) and sustain in the long term.
i. Reached when population growth is checked by the resistance
factors. ii. Carrying capacity is not always set in stone and can
fluctuate.
iii. Advances in agriculture are one example of how carrying capacity can
be increased.
iv. List one other:

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19. Assessing Growth Rate in a Population
a. Total fertility rate (TFR) – average number of children per woman (in an
area or country)
 b. Replacement TFR is 2.1
i. Close to zero population growth. This means that the death rate and
birth rate are about the same
c. If TFR drops below the replacement rate of 2.1
i. The population will decrease over time.
ii. Death rate will be higher than births.
d. If the TFR rises above the replacement rate
i. The population will increase

Collaborative Catch-up: Fertility Rate and Population Growth

Review the fertility rates in the table below and summarize the pattern of
population growth based on TFR.
Table 1-3. PROJECTED WORLD POPULATION BASED ON NUMBER
OF CHILDREN PER FAMILY- 2019 7.3 billion people

TOTAL
POPULATION BY
POPULATION BY
POPULATION BY
FERTILITY RATE
2038
2078
2119
(TFR)
(20 years)
(60 years)
(100 years)
(BILLIONS)
(BILLIONS)
(BILLIONS)

2.6 8.2 11.8 19.3

2.1 7.4 8 8.8

1.6 6.8 5.2 3.5

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20. Age Pyramids Reveal Much About a Population
a. A visual representation of population growth
b. Age pyramids show the number of individuals in a population within any
 age group.
c. They can show if a population is rapidly growing, staying stable or
decreasing. i. A rapidly growing population will have a large base and small
top
ii. A stable population that is close to zero growth rate will be
more columnar in shape.
iii. A decreasing population will have a smaller base than the top
d. Look at the examples below.
i. Which one is rapidly growing? _________
ii. Which one is decreasing? __________
iii. Which one is stable? ___________

Figure 1-16. Population Age Pyramids17

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Image Attribution

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Extra Credit (optional) Assignment (5 points): Population Growth
IF your instructor assigns this as extra credit, submit it according to their instructions.

Go to the following website: https://www.census.gov/data

tools/demo/idb/#/dashboard?COUNTRY_YEAR=2024&COUNTRY_YR_ANIM=2024

It should appear like this:

 Figure 1-17. US Census Age Pyramid18
Look to the pyramid at the right side of the page and click on the play button to watch
the population change over time.

Review the world information including the growth curve on the left side of the
information.

1. How would you describe the world growth rate?

a. rapidly growing
b. slowly growing
c. stable
d. slowly decreasing
e. rapidly decreasing

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Image Attribution

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Look at the data and the video for the USA.
2. How would you describe the U.S.?
a. rapidly growing
b. slowly growing
c. stable
d. slowly decreasing
e. rapidly decreasing
 Look at the data for one other country.
3. What country did you choose?
a. Take a screenshot of the population pyramid for your chosen country and
place it into your extra credit assignment document.
b. Summarize the pattern of growth you see in that population.

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