4 Gene Pool and Genetic Diversity

Question 1

population

Answer 1

a group of individuals of the same species occupying a particular habitat and a particular niche within that habitat

Question 2

gene pool

Answer 2

the sum total of all alleles in a population at a given time

Question 3

selection pressure (4)

Answer 3

• the effect of environmental factors that determine whether an organism will be more or less sucessfull at surviving and reproducing
• it drives speciation
• occurs when a change occurs in environment
• also non-random mating, so for example the most attractive bird will attract the most females, this means it is not random mating and is a selection pressure

Question 4

process of natural selection (5)

Answer 4

1. a population has some naturally-occuring genetic variation with new alleles created through mutations
2. a change in the environment causes a change in the selection pressures acting on the population
3. an allele that was previously of no particular advantage now becomes favourable
4. organisms with the allele are more likely to survive, reproduce and so produce offspring
5. their offspring are more likely to have that allele, so it becomes more common in the population

Question 5

formula for allele frequencies for dominant and recessive phenotypes in gene pool of population

Answer 5

p+q= 1
p= frequency of dominant allele
q= frequency of recessive allele

Question 6

The Hardy-Weinberg equilibrium

Answer 6

• used to describe the mathematical relationship between the frequencies of alleles and the genotype within a stable theoretical population that is not evolving
• states that in a population that is not evolving, the allele frequencies in a population will remain stable from one generation to the next

Question 7

Hardy-Weinberg formula

Answer 7

p 2 + 2pq + q 2 = 1
p 2= frequency of homozygous dominant genotype in population
2pq= frequency of heterozygous genotype in population
q 2= frequency of homozygous recessive genotype in population

Question 8

What is needed in a theoretical population for the hardy weinberg equilibrium to work? (5)

Answer 8

• there are no mutations
• there is random mating
• the population is large
• the population is isolated (no immigration or emigration)
• there is no selection pressure (all genotypes are equally fertile/successfull)