Evolution

Question 1

What is evolution?

Answer 1

Evolution is the change over time in the proportion of individuals in a population differing in one or more inherited genes.

Question 2

State the two non- random process involved in evolution.

Answer 2

Natural and sexual selection.

Question 3

State a random process of evolution.

Answer 3

Genetic drift

Question 4

What is the original source of new sequences of DNA?

Answer 4

Mutation

Question 5

What is selection?

Answer 5

Selection results in the non-random increase in the frequency of advantageous alleles and the non-random decrease in the frequency of deleterious alleles.

Question 6

What is sexual selection?

Answer 6

Sexual selection is the non-random process involving the selection of alleles that increase the individuals chances of mating and producing offspring.

Question 7

What is sexual dimorphism?

Answer 7

When sexual selection leads to a difference in from between male and female individuals.

Question 8

State the two parts that sexual selection is due to.

Answer 8

Male-male rivalry

Female choice

Question 9

What is involved in male-male rivalry?

Answer 9

Large size or weaponry that increase access to females through success in conflict.

Question 10

What does female choice involve?

Answer 10

Involves females assessing the fitness of males.

Question 11

What are selection pressures?

Answer 11

The environmental factors that influence which individuals in a population pass on their alleles.

Question 12

State the two types of selection pressures and give examples of each.

Answer 12

• biotic, examples include; competition, predation, disease and parasitism
• abiotic, examples include; temperature, light, humidity, pH and salinity

Question 13

When selection pressures are strong, what is the rate of evolution?

Answer 13

Rapid

Question 14

What does the Hardy- Weinberg Principle state?

Answer 14

In the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations.

Question 15

State the Hardy-Weinberg equation.

Answer 15

P^2 + 2pq + q^2 = 1

Question 16

What does the p^2 in the Hardy-Weinberg equation mean?

Answer 16

The frequency of homologous dominant genotypes.

Question 17

What does 2pq in the Hardy-Weinberg equation mean?

Answer 17

The frequency of heterozygous genotype.

Question 18

What does q^2 in the Hardy-Weinberg equation mean.

Answer 18

The frequency of homozygous recessive genotype.

Question 19

When is genetic drift more common?

Answer 19

In smaller populations. (Alleles are more likely to be lost from the gene pool)

Question 20

Explain an example of genetic drift.

Answer 20

The population bottleneck effect is an example of genetic drift that can occur when a population size is reduced for at least one generation.

Question 21

How is the gene pool altered?

Answer 21

By genetic drift because certain alleles may be under-represented or over-represented, and so allele frequencies change.

Question 22

Explain what is meant by fitness.

Answer 22

Fitness is an indication of an individual’s ability to be successful at surviving and reproducing. Fitness is a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species.

Question 23

What is meant by absolute fitness?

Answer 23

Absolute fitness is the ratio between the frequency of individuals of a particular genotype after selection, to those before selection.

Question 24

What does an absolute fitness of 1 indicate.

Answer 24

The frequency of that genotype is stable.

Question 25

Explain what is meant by relative fitness.

Answer 25

Relative fitness is the ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype.

Question 26

What is co-evolution?

Answer 26

Co-evolution is the process by which two or more species evolve in response to selection pressures imposed by each other. A change in the traits of one species acts as a selection pressure on the other species.

Question 27

Explain what is meant by symbiosis.

Answer 27

Symbiosis is a co-evolved intimate relationship between members of two different species.

Question 28

Explain what mutualism is.

Answer 28

Mutualism is a symbiotic relationship in which the species in the interaction are interdependent on each other for resources or other services and since both species gain, the interaction is (+/+).

Question 29

Explain what commensalism is.

Answer 29

Commensalism is a symbiotic relationship in which only one of the species substantially benefits and, for the other, the relationship is neither substantially positive or negative, so is neutral (+/0).

Question 30

Explain what parasitism is.

Answer 30

Parasitism is a symbiotic relationship in which the parasite species benefit in terms of energy or nutrients while the host species is harmed by the loss of these resources (+/-).

Question 31

What does the Red Queen Hypothesis State?

Answer 31

That in a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species, which must adapt to avoid extinction.