Evolution

Question 1

What is evolution?

Answer 1

The changes in organisms over generations as a result of genomic variation.

Question 2

What is meant by vertical gene transfer?

Answer 2

Transfer of genetic information from parents to offspring by sexual or asexual reproduction.

Question 3

What is meant by horizontal gene transfer?

Answer 3

Transfer of genetic information between individuals.

Question 4

Which type of gene transfer leads to rapid evolutionary change?

Answer 4

Horizontal Gene Transfer

Question 5

Which organisms only transfer genetic material by vertical gene transfer?

Answer 5

Eukaryotes

Question 6

Which organisms can transfer genetic information by both vertical and horizontal gene transfer?

Answer 6

Prokaryotes

Question 7

Which organisms can horizontally transfer genetic information into the genome of eukaryotes?

Answer 7

Viruses and bacteria

Question 8

What is Natural Selection?

Answer 8

The non-random increase in the frequency of DNA sequences which increase survival.

Question 9

What is Sexual Selection?

Answer 9

The non-random increase in frequency of DNA sequences which increase reproductive success.

Question 10

What is meant by ‘stabilising selection’?

Answer 10

Favours an intermediate trait.

Question 11

What is meant by ‘disruptive selection’?

Answer 11

Favours the extreme versions of a trait and splits the population into two groups with their own mean values.

Question 12

What is meant by ‘directional selection’?

Answer 12

Favours a less common version of a trait until it becomes the most popular.

Question 13

Summarise natural selection.

Answer 13

Organisms who are better adapted to their environment are more likely to survive to pass on their genes.

Question 14

What are the two types of selection that lead to a non-random change in the frequencies of alleles?

Answer 14

Natural and Sexual selection.

Question 15

What is ‘Genetic Drift’?

Answer 15

The random increase and decrease in the frequency of sequences particularly in small populations.

Question 16

What is meant by the founder effect?

Answer 16

When a small group of organisms is separated from its population and starts a new population.

Question 17

How can the founder effect lead to the loss of genetic variation?

Answer 17

The frequency and range of alleles are unrepresentative of the original population so some alleles may disappear.

Question 18

Which type of mutation can change the frequency of alleles?

Answer 18

Neutral mutations

Question 19

Which two factors things can lead to genetic drift?

Answer 19

Founder effect, neutral mutations.

Question 20

What is the definition of a species?

Answer 20

Organisms which can interbreed to produce fertile offspring.

Question 21

What is speciation?

Answer 21

The formation of new species brought about by isolation, mutation and selection.

Question 22

What is meant by allopatric speciation?

Answer 22

Speciation brought about by geographical barriers e.g. River, sea, mountain range.

Question 23

What is meant by sympatric speciation?

Answer 23

Speciation brought about by a behavioural or ecological barrier e.g. Different breeding seasons, different mating rituals.

Question 24

What is meant by a hybrid zone?

Answer 24

A region occupied by several populations which can interbreed.

Question 25

What can happen if a hybrid zone disappears?

Answer 25

Members of the original population may no longer be able to interbreed and speciation could occur.

Question 26

How do you know if organisms have undergone speciation?

Answer 26

They can no longer interbreed to produce fertile offspring.

Question 27

Which evolutionary mechanism is described as non-random?

Answer 27

Genetic Drift

Question 28

What is meant by “gene pool”?

Answer 28

All of the different alleles present in a population.