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 organisms of the same species in a particular space at a particular time
● That can (potentially) interbreed (to produce fertile offspring

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. Random gene mutations can result in [named] new alleles of a gene
2. In certain environments, the new allele might benefit its possessor
   → organism has a selective advantage
3. Possessors are more likely to survive and have increased reproductive success
4. Advantageous allele is inherited by members of the next generation (offspring)
5. 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 surviv

Question 8

Directional selection

Answer 8

Example-Antibiotic resistance in bacteria

Key feature:

Organisms with an extreme variation of a
trait eg. bacteria with high level of
resistance to a particular antibiotic
Often a change in the environment, eg. antibiotic introduced

Effect:
● Increased frequency of organisms with
/ alleles for extreme trait
● Normal distribution curve shifts
towards extreme trait

Question 9

Stabilising selection

Answer 9

Example:Human birth weight

Organisms with an average / modal
variation of a trait eg. babies with an
average weight

Usually stable environment

● Increased frequency of organisms
with / alleles for average trait
● Normal distribution curve similar, less
variation around the mean