genetic diversity and adaption

Question 1

Define genetic diversity

Answer 1

The number of different alleles of genes in a population

Question 2

what is selection

Answer 2

the process by which organisms better adapted to their environment survive and breed, whilst those who are less adapted die

Question 3

distinguish between stabilising selection and directional selection

Answer 3

directional- extreme phenotypes are favoured, changes characteristics of a population, distribution curve remains same shape but shifts left or right

stabilising- phenotypes around the mean are favoured, preserves characteristics of a population, distribution curve becomes narrower and higher but mean is constant

Question 4

describe the process of natural selection (4)

Answer 4

• random mutation results in new alleles of a gene
• mutations may be harmful but can be advantageous in some environments
• advantageous allele is inherited by members of next generation
• allele frequency increases within the population over many generations

Question 5

Define ‘gene mutation’ and explain how a gene mutation can have:

*        no effect on an individual

*        a positive effect on an individual (6)

Answer 5

1. change to base sequence of DNA
2. results in formation of new allele

no effect
3. genetic code is degenerate
4. change to amino acid but no effect on tertiary structure
5. allele is recessive so no effect on phenotype

positive effect
6. change in polypeptide positively changing properties of protein
7. results in increased survival

Question 6

in Africa most of the human pop today are resistant to malaria caused by
P.vivax.

use your knowledge of natural selection to explain why this resistance is so common (4)

Answer 6

• random mutation caused formation of new allele
• those with allele more likely to survive malaria
• so more likely to reproduce and pass on allele
• allele frequency increases