genetic diversity and adaptation

Question 1

What is genetic diversity?

Answer 1

Number of different alleles of genes in a population

Question 2

What are alleles and how do they arise?

Answer 2

● Variations of a particular gene (same locus) → different DNA base sequence
● Arise by mutation

Question 3

What is a population?

Answer 3

A group of interbreeding individuals of the same species

Question 4

Explain the importance of genetic diversity

Answer 4

● Enables natural selection to occur
● As in certain environments, a new allele of a gene might benefit its possessor
● By resulting in a change in the polypeptide (protein) coded for that positively changes its properties
● Giving possessor a selective advantage (increased chances of survival and reproductive success)

Question 5

What is evolution?

Answer 5

● Change in allele frequency (how common an allele is) over many generations in a population
● Occurring through the process of natural selection

Question 6

Explain the principles of natural selection in the evolution of populations

Answer 6

1. Mutation
   Random gene mutations can result in [named] new alleles of a gene
2. Advantage
   In certain [named] environments, the new allele might benefit its possessor [explain why] → organism has a selective advantage
3. Reproductive success Possessors are more likely to survive and have increased reproductive success
4. Inheritance Advantageous allele is inherited by members of the next generation (offspring)
5. Allele frequency
   Over many generations, [named] allele increases in frequency in the population

Question 7

Describe 3 types of adaptations

Answer 7

● Anatomical - structural / physical features that increase chance of survival

● Physiological - processes / chemical reactions that increase chance of survival

● Behavioural - ways in which an organism acts that increase chance of survival

Question 8

Explain two types of selection, with examples

Answer 8

Directional selection
- eg. Antibiotic resistance in bacteria
- selective advantage to organisms with an extreme variation of
a trait eg. bacteria with high level of
resistance to a particular antibiotic
- change in environment Yes, usually eg. antibiotic introduced
- Increased frequency of organisms
with / alleles for extreme trait
- Normal distribution curve shifts
towards extreme trait

Stabilising selection
- eg. Human birth weight
- selective advantage to organisms with an average / modal variation of a trait eg. babies with an
average weight
- change in environment No, usually stable
- Increased frequency of organisms
with / alleles for average trait
- Normal distribution curve similar,
less variation around the mean