Essential Biology 5.4 Evolution
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Complete the self-assessment rubric before submitting.
You should complete the reader ‘Evolution and Darwin’ before this Essential Biology worksheet.
1. Define evolution.
Evolution is when there is a change to the population of a species to suit its
environment or situation.
2. Populations tend to produce more offspring than the environment can support.
a. Explain how the following lead to a ‘struggle for survival’

Competition for food
This leads to a struggle for survival because animals have reach their prey before the
other animals, and they have to catch their prey.

Competition for mates
There will be a competition of attracting mates. Animals will fight over mates, and there
will be less mates to choose from. They will also need to provide for their mate and
offspring.

Competition for space
With so many animals, there will be less room to rest, and have shelter, as well as less
room to reproduce.

Parasitism
Parasites will target the populous area, invading it. Animals will have to avoid the
parasites, remove them, or simply try and tolerate them.

Disease
In such a highly populated area, diseases tend to appear and spread rapidly. Like
parasites, animals will need to avoid, remove, or tolerate the diseases when they
appear.

Predation
With so many animals, there will be a lot less prey. Animals will have to fight for food to
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Essential Biology 5.4 Evolution
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stay alive. To survive, prey must be able to avoid or escape their predators.
b. Explain the significance of variation within a species in relation to survival.
Variation between species is important in relation to survival because if a species has a trait
that helps protect it from predators, for example a different colored body which will
camouflage it, they stand a better chance in evading predation than other animals of their
species.
c. Outline how the following aspects of sexual reproduction contribute to variation within a
species:
Meiosis: Meiosis contributes to variation within a species by recombination and the
crossing over of chromosomes.
Random fertilization: Random fertilization contributes to variation within a species
because each zygote formed from fertilization is unique.
Mutation: Mutation contributes to variation within a species by DNA replication and viral
infection.
d. State which of the above is the main source of variation within genes.
Random fertilization is the main source of variation within genes.
e. Explain the term descent with modification.
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Essential Biology 5.4 Evolution
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Descent with modification was the term used by Charles Darwin instead of the term
evolution. It means that with each generation of a population that passes, there is a
change, which becomes more evident each generation.
f.
Describe how the struggle for survival lead to natural selection.
The struggle for survival led to natural selection by: the animal gets an advantageous
variation selected for survival. Therefore, that animal is more likely to reproduce and pass
on genes. Gene frequency then increases, and the population evolves to adjust to the
environment.
3. Antibiotic resistance in bacteria is an example of evolution.
a. What is Staphylococcus aureus?
The common name for Staphylococcus aureus is ‘golden cluster seed’.
b. Distinguish between MRSA and MSSA.
The difference between MRSA and MSSA is that MRSA is resistant to many antibiotics
while MSSA responds well to antibiotics.
c. Use the key terms environmental change, variation, survival, reproduction to annotate
this diagram, explaining how antibiotic resistance has evolved.
Original population:
Source of variation:
Environmental change:
Effect on population:
Selection for:
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Inheritance:
''........can we doubt (remembering that many more individuals are born than can possible survive) that
individuals having any advantage, however slight, over others, would have the best chance of surviving
and procreating their kind? On the other hand, we may feel sure that any variation in the least injurious
would be rigidly destroyed. This preservation of favourable variations and the rejection of injurious
variations, I call Natural Selection' Darwin C. (1859) The Origin of Species
4. Explain one other example of evolution of a species, in response to environmental change.
(Galapagos finches or pepper moths)
One other example of evolution of a species in response to environmental change is
5. Research Another reliable source of evidence to support the theory of evolution by natural
selection is the fossil record—paleontologists have been uncovering fossilized remains of
species from sedimentary rock deposits and using this information to create timelines of
changes in the earth and development of species.
a. Outline formation of sedimentary rock.
The formation of sedimentary rock involves weathering, deposition, erosion,
lithification, and compaction.
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Essential Biology 5.4 Evolution
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b. Describe how the position of a fossil in sedimentary rock give a clue to its position in
time.
The position of a fossil in sedimentary rock gives a clue to its position in time because
generally the deeper the fossil is underground, the older the fossil is.
c. State some other methods used to confirm the age of fossils.
Other methods used to confirm the age of fossils are the age of rocks around a fossil,
mathematical calculations, the state of decay, carbon-14 and isotopes figure in
calculations and tree of life relationships.
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Essential Biology 5.4 Evolution
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6. Homologous structures
a. Define homologous
Homologous means having the same origin of evolution but not necessarily the same
function.
b. One of the most obvious examples of homologous structures in animals is the
pentadactyl limb.
Define pentadactyl.
Pentadactyl means having 5 fingers or toes on one hand or foot.
c. Homologous structures has evolved through ‘adaptive radiation’. Explain this term.
source: http://en.wikipedia.org/wiki/File:Evolution_pl.png
Adaptive radiation means the development of many different forms from a group of
organisms that were originally homogeneous.
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Essential Biology 5.4 Evolution
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Darwin described structures such as these as having a ‘unity of type’ - although they look different, on
closer inspection they share features. In this case, the bones are the same, though differently shaped.
7. Selective breeding of domesticated animals
a. State the purpose of selective breeding
The purpose of selective breeding is to develop livestock whose beneficial traits have
components that make them easier to be inherited and can be propagated.
b. Describe why selective breeding is also known as artificial selection.
Selective breeding is also known as artificial selection because the animal is bred with
man choosing what it will breed with, instead of letting it choose its own mate.
Artificial selection, like natural selection, can work in two ways. State examples of each:
c. Selection for
Examples of selection for are: fast racehorses, god-natured domestic animals, and
strong bulls.
d. Selection against
Examples of selection against are: diseased pets, lazy horses and domestic animals that
have an extremely violent personalities.
ToK AoK: “It’s only a theory.” Explain, using the scientific method, why evolution is described as a theory
and why this represents a high level of certainty in science. What is the linguistic confusion that leads
some non-scientists to question the validity of evolution as scientific truth?
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Essential Biology 5.4 Evolution
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Works Cited
1. Allott, Andrew. IB Study Guide: Biology for the IB Diploma. s.l. : Oxford University Press, 2007. 978-019-915143-1.
Self Assessment:
Essential Biology
Criterion
Assessment
Complete (2)
Partially complete (1)
Self
Presentation &
Organisation
NA
File names sensible, work complete and wellpresented. Sentences are complete and include
vocabulary. All command terms highlighted or
underlined.
1
Academic
Honesty
NA
Sources cited using mla method, with Works Cited
section complete and correct.
1
Objective 1
understanding
Objective 2
understanding
Objective3
understanding
Logic, notation,
mathematical
working
Further research
All answers for the following command terms
correct:
Define
Draw
Label
Most answers for the following command terms
correct:
List
Measure State
Most answers for the following command terms
All answers for the following command terms correct:
correct:
Annotate Apply
Calculate Describe Distinguish Estimate Identify
Outline
Most answers for the following command terms
All answers for the following command terms correct:
correct:
Analyse Comment Compare Construct Deduce Derive Design Determine Discuss
Evaluate
Explain Predict
Show Solve
Sketch Suggest
Answers are presented in a logical and concise
manner. SI units used most times, with correct
NA
unit symbols and definitions of terms. All
mathematical working shown.
Evidence is apparent of research and reading
beyond the textbook and presentations to find
correct answers to challenging questions. If any
NA
questions are unanswered, this criterion scores
zero.
Total (max 10):
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2
1
2
1
0
8
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