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Senior High School
General Biology 2
Quarter 1- - Module 2
GENERAL BIOLOGY 2
Department of Education ● Republic of the Philippines
Lesso n Evidences of Evolution
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What I need to know
Learning Competency
The learners explain evidences of evolution (e.g. fossil record, biogeography,
DNA/ protein sequences, homology and embryology (STEM_BIO11/12-IIIc- g-
12)
Specific Learning Outcomes
At the end of the lesson, the learners will be able to:
• describe the evidences to support evolution and
• explain some modern evidences of evolution
What I know
PRIOR KNOWLEDGE: Definition of Terms
1. Homologous 6. Genetic code
2. Analogous 7. Biogeography
3. Molecular Biology 8. Fossils
4. Transcription 9. Evolution
5. Translation 10. Modification
What’s new
PRE-ACTIVITY: Video
1. List down 5 evidences of evolution.
2. Fossils & Evidence for Evolution:
https://www.youtube.com/watch?v=iYr3sYS9e0w
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What’s is it
Introduction:
The Evidence for Evolution Anatomy and embryology Darwin thought
of evolution as "descent with modification," a process in which species
change and give rise to new species over many generations. He proposed
that the evolutionary history of life forms a branching tree with many
levels, in which all species can be traced back to an ancient common
ancestor.
Homologous features If two or more species share a unique physical
feature, such as a complex bone structure or a body plan, they may all
have inherited this feature from a common ancestor. Physical features
shared due to evolutionary history (a common ancestor) are said to be
homologous.
Analogous features To make things a little more interesting and
complicated, not all physical features that look alike are marks of
common ancestry. Instead, some physical similarities are analogous:
they evolved independently in different organisms because the
organisms lived in similar environments or experienced similar selective
pressures. This process is called convergent evolution. (To converge
means to come together, like two lines meeting at a point.)
Determining relationships from similar features In general,
biologists don't draw conclusions about how species are related on the
basis of any single feature they think is homologous. Instead, they study
a large collection of features (often, both physical features and DNA
sequences) and draw conclusions about relatedness based on these
features as a group. We will explore this idea further when we examine
phylogenetic trees.
Molecular biology Like structural homologies, similarities between
biological molecules can reflect shared evolutionary ancestry. At the
most basic level, all living organisms share:
The same genetic material (DNA)
The same, or highly similar, genetic codes
The same basic process of gene expression (transcription and
translation)
The same molecular building blocks, such as amino acids
Biogeography The geographic distribution of organisms on Earth
follows patterns that are best explained by evolution, in combination
with the movement of tectonic plates over geological time.
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Fossil record Fossils are the preserved remains of previously living
organisms or their traces, dating from the distant past. The fossil record
is not, alas, complete or unbroken: most organisms never fossilize, and
even the organisms that do fossilize are rarely found by humans.
What’s more
ACTIVITY:
Identify the evidence shown by the picture and explain how it supports evolution.
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5
Lesson
Evolutionary Relationships of
Organisms
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What I need to know
Learning Competency
The learners should be able to infer evolutionary relationships among
organisms using the evidences of evolution (STEM_BIO11/12-IIIc-g-13)
Specific Learning Outcomes
At the end of the lesson, the learners will be able to:
• recognize how comparisons of similarities and differences can suggest
evolutionary relationships;
• explain the significance of using multiple lines of evidence to identify
evolutionary relationships;
• infer the degree of relationships among organisms based on the amino acid
sequence in the cytochrome c molecule;
• compare four species of horses by measuring structures in their hind legs;
and
• differentiate various hominids by describing their physical features.
What I know
PRIOR KNOWLEDGE: Definition of Terms
1. Phylogeny 6. Polytomy
2. Phylogenetic Tree 7. Taxonomy
3. Branch Point 8. Binomial Nomenclature
4. Basal Taxon
5. Sister Taxa
6
What’s new
PRE-ACTIVITY:
1. Recall and Write the evidences of Evolution.
What’s is it
Introduction:
INFERRING RELATIONSHIPS FROM EVIDENCES OF EVOLUTION
Living things share some biomolecules which may be used to prove
relationships. These chemicals include DNA and proteins. The building blocks
of these chemicals may be analyzed to show similarities and differences
among organisms. The more similarities, the closer the relationships.
One of these is the protein cytochrome-c, an important enzyme found in
virtually all organisms. It is a highly conserved protein which functions in the
electron transport chain system of the mitochondria which is needed for the
release of energy from food. It also performs a role in apoptosis (programmed
cell death) by being released into the cytosol activating the events of cell death.
There are 104 amino acids in the human cytochrome c, 37 of which have been
found at the same position in every cytochrome c that has been sequenced.
The molecules are assumed to have descended from a primitive microbial
cytochrome that existed over two billion years ago.
A cladogram is a diagram used to represent a hypothetical relationship
between groups of animals, called a phylogeny. A cladogram is used by a
scientist studying phylogenetic systematics to visualize the groups of
organisms being compared, how they are related, and their most common
ancestors.
A phylogeny is a hypothetical relationship between groups of organisms being
compared. A phylogeny is often depicted using a phylogenetic tree.
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A phylogenetic tree is a diagram used to reflect evolutionary relationships
among organisms or groups of organisms. Scientists consider phylogenetic
trees to be a hypothesis of the evolutionary past since one cannot go back to
confirm the proposed relationships. In other words, a “tree of life” can be
constructed to illustrate when different organisms evolved and to show the
relationships among different organisms
a phylogenetic tree can be read like a map of evolutionary history. Many
phylogenetic trees have a single lineage at the base representing a common
ancestor.
Scientists call such trees rooted, which means there is a single ancestral
lineage (typically drawn from the bottom or left) to which all organisms
represented in the diagram relate. Notice in the rooted phylogenetic tree that
the three domains— Bacteria, Archaea, and Eukarya—diverge from a single
point and branch off. The small branch that plants and animals (including
humans) occupy in this diagram shows how recent and miniscule these
groups are compared with other organisms. Unrooted trees don’t show a
common ancestor but do show relationships among species.
In a rooted tree, the branching indicates evolutionary relationships (Figure 3).
The point where a split occurs, called a branch point, represents where a
single lineage evolved into a distinct new one. A lineage that evolved early from
the root and remains unbranched is called basal taxon. When two lineages
stem from the same branch point, they are called sister taxa. A branch with
more than two lineages is called a polytomy and serves to illustrate where
scientists have not definitively determined all of the relationships. It is
important to note that although sister taxa and polytomy do share an
ancestor, it does not mean that the groups of organisms split or evolved from
each other. Organisms in two taxa may have split apart at a specific branch
point, but neither taxa gave rise to the other.
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https://courses.lumenlearning.com/suny-wmopen-biology2/chapter/phylogenies-
and-the-
historyoflife/#:~:text=In%20scientific%20terms%2C%20the%20evolutionary,closel
y%20related%2C%20and% 20so%20forth.
What’s more
ACTIVITY: Phylogenetic Tree
1. Illustrate the Phylogenic Tree of Human Ancestors.
What’s I’ve learned
POST QUIZ: Amino Acid Sequences of in Cytochrome-c
Animals Amino acid Sequence
Horse
Chicken
Frog
Human
Shark
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