Population

Question 1

Explain what is meant by the term population.

Answer 1

• Species exist as one or more populations. Population:
• Group of organisms of same specie
• Occupying a particular space at a particular time
• That can potentially interbreed

Question 2

Gene pool

Answer 2

• Range of alleles that exist in a population

Question 3

Explain what is meant by the term allele frequency.

Answer 3

How often allele occurs in a population

• Usually % or number e.g. 0.35 or 35%

Question 4

What is the Hardy Weinberg principle?

Answer 4

• Mathematical model
• Predicts that the allele frequencies will not change from generation to generation

Question 5

What are the conditions under which the Hardy
Weinberg principle applies?

Answer 5

• Large population
• No immigration /emigration
• No mutations arising
• No natural selection

Question 6

The frequency of alleles, genotypes and phenotypes in a population can be calculated using the
Hardy-Weinberg equation. Give the 2 equations and what each term stands for.

Answer 6

• Frequency of the dominant allele is noted p while that of the recessive allele
  is noted q
  Both must account for the whole population, therefore:
  p + q = 1
• P2 + 2pq + q2 = 1
• p2 = frequency of homozygous dominant genotype
• 2pq = frequency of heterozygous genotype
• q2 = frequency of homozygous recessive genotype