2.4.3 Natural Selection

Question 0

What does ‘survival of the fittest’ mean?

Answer 0

Survival of the fittest is the mechanism by which organisms change over time as they adapt to their changing surrounding environment

Question 1

What is natural selection?

Answer 1

Natural selection is the mechanism by which organisms change over time as they adapt to their changing environments

Question 2

What is ‘evolution’?

Answer 2

Evolution is defined as ‘a change in allele frequency in a population over time’

Question 3

What is the process of evolution by natural selection?

Answer 3

• random mutations cause genetic variation
• a change in the environment causes selection pressure
• the allele change is favourable
• organisms with this allele are more likely to survive and reproduce
• their offspring are likely to have the allele, so it becomes more common in the population

Question 4

When does natural selection occur?

Answer 4

Natural selection is always occurring, but it is slow and difficult to observe over a human lifetime

Question 5

Describe the natural selection that happens with bacteria?

Answer 5

The use of antibiotics is leading to evolution of resistant forms of bacteria

Question 6

What does the ability of a population to adapt depend on?

Answer 6

• the strength of the selection pressure
• the size of the gene pool
• the reproductive rate of the organisms

Question 7

What does a gene pool consist of?

Answer 7

A gene pool consists of all the alleles of all the genes present in a population

Question 8

What can be said about populations with larger gene pools?

Answer 8

Populations with larger gene pools are said to have greater biodiversity