Evolution
Past Paper Questions
1. Explain the factors that cause a
population to follow the sigmoid ( Sshaped) growth curve. (8 max)
1. Explain the factors that cause a population to
follow the sigmoid ( S-shaped) growth curve. (8 max)
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during exponential growth the population grows at an increasing rate
all / most / many offspring survive / birth rate higher than death rate
all / most / many offspring reproduce
each generation produces more offspring that the last
plateau reached eventually / population levels off / birth rate equals death
rate
when carring capacity of environment is reached
e.g. when no more food / nutrients / resources available
e.g. when no more space for nesting / space for another purpose is
available
e.g. when numbers of predators have increased
e.g. when levels of parasites / diseases have become very high
transitional phase when limits to growth are starting to act
2. Apply the concept of carrying
capacity to the struggle for survival
resulting from overproduction of
offspring. (5 max)
2. Apply the concept of carrying capacity to the
struggle for survival resulting from overproduction of
offspring. (5 max)
• the environment can only support a certain maximum
population
• this population is sometimes exceeded (due to
overproduction of offspring)
• food / space / resources are insufficient / competition
for resources
• some individuals fail to obtain enough
• deaths / failure to reproduce / survival of the fittest
• population falls to carrying capacity
• reference to evolution by natural selection
3. Discuss the definition of the term
species. (8 max)
3. Discuss the definition of the term species. (8 max)
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species is a group of organisms
a species shares a common gene pool
showing similar morphology / characteristics
capable of interbreeding
and producing fertile offspring
but dissimilar organisms sometimes interbreed
mule formed by crossing horse and donkey / other example of
interspecific hybridisation
interspecific hybrids are sometimes fertile
sometimes organisms that are very similar will not interbreed
Drosophila pseudoobscura and persimilis / other example of sibling species
reference to the problem of defining fossil species
reference to the problem of species that only reproduce asexually
reference to the problem of isolated populations gradually diverging
4. Outline two modern examples
where evolution can be observed. 2
marks
4. Outline two modern examples where evolution can
be observed. 2 marks
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change of beak shape in Galapagos finches
resistance to pesticides/antibiotics
bird predation on moths
heavy metal tolerance in plants
melanism in ladybird beetles
5. Outline one modern example of
observed evolution by natural
selection. 2 marks
5. Outline one modern example of observed evolution
by natural selection. 2 marks
• named example
• selective pressure
• Result
example
• beaks of Galapagos finches
• competition for food
• change in numbers/proportion of birds with
different sized beaks
6. Outline five types of evidence
which support the theory of evolution
by natural selection. 6 marks
6. Outline five types of evidence which support the
theory of evolution by natural selection. 6 marks
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geographic distribution
ring species/other evidence from geographical distribution
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biochemistry
cytochrome c/other biochemical evidence
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fossils/paleontological
fossilized horse ancestors/other evidence
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homologous structures
pentadactyl limb/vertebrate embryos/other
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recent observed evolution
resistance to antibiotics/insecticides/heavy metal tolerance/other recent example
7. Explain the evidence from
homologous anatomical structures
that supports the theory of evolution.
6 marks
7. Explain the evidence from homologous anatomical
structures that supports the theory of evolution. 6
marks
• homologous structures are various different structures of
the same basic plan
• derived from a similar embryonic origin
• variations on the basic structure allow different functions
• permitting exploitation of differnt ways of life/adaptive
radiation
• the suggests divergence from a common ancestor
• named example of a homologous structure (e.g.
pentadactyl limb, flower, birds` beaks)
• description of basic structure of this example
• variation related to different functions of this example