Evolution 1.7

Question 1

What is evolution?

Answer 1

Evolution — the changes in organisms
over generations as a result of genomic
variations.

Question 2

What is natural selection?

Answer 2

Natural selection is the non-random
increase in frequency of DNA sequences
that increase survival and the non-random
reduction in the frequency of deleterious
sequences.

Question 3

What are the three types of selection that can change the phenotype frequency?

Answer 3

The changes in phenotype frequency as a
result of stabilising, directional and
disruptive selection.

Question 4

What happens in stabilising selection?

Answer 4

In stabilising selection, an average
phenotype is selected for and extremes of
the phenotype range are selected against.

Question 5

What happens in directional selection?

Answer 5

In directional selection, one extreme of the
phenotype range is selected for.

Question 6

What happens in disruptive selection?

Answer 6

In disruptive selection, two or more
phenotypes are selected for.

Question 7

What is horizontal gene transfer?

Answer 7

Horizontal gene transfer is where genes
are transferred between individuals in the
same generation.

Question 8

What organism is natural selection fastest in and why?

Answer 8

Natural selection is more rapid in
prokaryotes. Prokaryotes can exchange
genetic material horizontally, resulting in
faster evolutionary change than in
organisms that only use vertical transfer.

Question 9

What is vertical gene transfer?

Answer 9

Vertical gene transfer is where genes are
transferred from parent to offspring as a
result of sexual or asexual reproduction.

Question 10

What is speciation?

Answer 10

Speciation is the generation of new
biological species by evolution as a result
of isolation, mutation and selection.

Question 11

What is a species?

Answer 11

A species is a group of organisms capable
of interbreeding and producing fertile
offspring, and which does not normally
breed with other groups.

Question 12

Why are isolation barriers important during speciation?

Answer 12

isolation barriers are important in preventing gene flow between subpopulations during speciation.

Question 13

What is the difference between allopatric and sympatric speciation?

Answer 13

Geographical barriers lead to allopatric
speciation and behavioural or ecological
barriers lead to sympatric speciation.