Genetic information - ADAPTATION AND NATURAL SELECTION

Question 1

What is genetic diversity?

Answer 1

The number of different alleles of genes in a population

Question 2

What is an allele?

Answer 2

Different forms of the same gene

Question 3

What is the allele frequency?

Answer 3

How often a particular allele occurs within a population

Question 4

What is the gene pool?

Answer 4

Gene pool is the set of all genes, or genetic information, in any population, usually of a particular species

Question 5

What is a population?

Answer 5

A group of individuals of the same species that live in the same place and can interbreed

Question 6

Why would increased genetic diversity lead to an increased chance of surviving in an environmental change? (4 marks)

Answer 6

• The greater the genetic diversity, the more likely that some individuals in a population will survive an environmental change
• Greater diversity means wider range of alleles and therefore wider range of characteristics
• Greater probability that some individuals will possess a characteristic that suits it to the new environmental condition
• Genetic diversity is a factor that enable natural selection to occur

Question 7

Suggest an explanation in the change in coloured moths after the industrial revolution (6 marks)

Answer 7

• Variation in a population due to random, rare population
• Due to trees blackening, white moths were more easily visible
• Predators were more able to see the white moths, hence population of white moths decreased
• Black moths were more able to hide, hence more likely to survive
• Black moths more likely to reproduce and pass on mutant allele
• Frequency of mutant allele increases in gene pool

Question 8

What is selection pressure?

Answer 8

• A change in the environment which causes mutation to occur
• Selection pressure determines which traits are successful

Question 9

What are the 3 types of selection?

Answer 9

• Disruptive
• Stabilising
• Directional

Question 10

What is directional selection?

Answer 10

• Favours individuals at one side of the mean
• Individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce

Question 11

What is stabilising selection?

Answer 11

• Favours the most common phenotype
• Individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
• Does not occur in a stable environment

Question 12

What is disruptive selection?

Answer 12

• Favours extreme individuals at either side of the mean

Question 13

What are the 3 types of adaptation that are not genetic

Answer 13

Behavioural adaptation - These increase the organisms chance of survival
Physiological adaptation - Metabolic processes inside an organisms body that increase its chance of survival
Anatomical adaptation - These are structural features that help the animals survive

Question 14

What type of selection is bacterial resistance to penicillin?

Answer 14

Directional selection

Question 15

How does bacteria become resistant to antibiotics?

Answer 15

• Spontaneous mutation in a bacteria’s gene which results in a new allele leading to the production of a new protein, enabling bacteria to break down penicillin
• Bacteria exposed to penicillin, those with the new allele have an advantage and are more likely to survive
• Bacterium reproduces and passes on advantageous allele to next generation
• Over many generations, bacteria becomes resistant to penicillin