Flashcards - Topic 7.2 Populations - AQA Biology A-level

Question 1

Define species.

Answer 1

A group of organisms that can interbreed to produce fertile offspring.

Question 2

Define population.

Answer 2

All the organisms of a particular species that live in the same place.

Question 3

Define gene pool.

Answer 3

The range of different alleles existing for a particular locus within a population.

Question 4

Define allele frequency.

Answer 4

The proportion of a certain allele within a gene pool, expressed as a decimal or percentage.

Question 5

What is the Hardy-Weinberg principle?

Answer 5

Allows us to estimate the frequency of alleles in a population, as well as if allele frequency is changing over time.

Question 6

Give the assumptions made by the Hardy-Weinberg principle.

Answer 6

? No mutations occur to create new alleles.
? No migration in or out of the population.
? No selection, so alleles are all equally passed on to the next generation.
? Random mating.
? Large population.

Question 7

Explain the Hardy-Weinberg equation for calculating allele frequency.

Answer 7

The frequencies of each allele for a characteristic must add up to 1.0. The equation is therefore; p + q = 1
Where p= frequency of the dominant allele, and q= frequency of the recessive allele.

Question 8

Explain the Hardy-Weinberg equation for calculating genotype frequency.

Answer 8

The frequencies of each genotype for a characteristic must add up to 1.0. The equation is therefore; p2 + 2pq + q2 = 1
Where p2= frequency of homozygous dominant,
2pq= frequency of heterozygous, and q2= frequency of homozygous recessive.