Genetic Diversity

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

Different versions of a particular gene→ 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 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 new alleles of a gene
2. Advantage - In certain environments, the new allele might benefit its possessor→ organism has a selective advantage
3. Reproduction - 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, allele increases in frequency in the population

Question 7

State 3 types of adaptations.

Answer 7

Anatomical
Physiological
Behavioural.

Question 8

Describe anatomical adaptations.

Answer 8

Structural / physical features that increase chance of survival.

Question 9

Describe physiological adaptations.

Answer 9

Processes / chemical reactions that increase chance of survival

Question 10

Describe behavioural adaptations.

Answer 10

Ways in which an organism acts that increase chance of survival.

Question 11

What are two types of selection?

Answer 11

Directional selection
Stabilising selection

Question 12

What is an example of directional selection?

Answer 12

Antibiotic resistance

Question 13

What is an example of stabilising selection?

Answer 13

Human birth weight

Question 14

What is directional selection?

Answer 14

Organisms with an extreme variation of a trait eg. bacteria with high level of resistance to a particular antibiotic.

Question 15

What is stabilising selection?

Answer 15

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

Question 16

What happens in the environment in directional selection?

Answer 16

Often a change - e.g. antibiotic introduced.

Question 17

What happens in the environment in stabilising selection?

Answer 17

Usually remains stable

Question 18

What effect does directional selection have on population over many generations?

Answer 18

• Increased frequency of organisms with alleles for extreme trait
• Normal distribution curve shifts
  towards extreme trait

Question 19

What effect does stabilising selection have on population over many generations?

Answer 19

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

Question 20

When can natural selection occur?

Answer 20

Natural selection can only occur if there is genetic diversity within a population..

Question 21

What does natural selection lead to?

Answer 21

Evolution in populations