Genetic Info, Variations And Relationships - Natural Selection

Question 1

Give the process of natural selection

Answer 1

1. New alleles for a gene are created by random mutations
2. If new allele increases chances of the individual surviving in that environment they are more likely to survive and reproduce
3. Reproduction passes on advantageous allele to next generation
4. Over many generations, new allele increases in frequency in the new population

Question 2

What are the types of natural selection?

Answer 2

Directional selection and stabilising selection

Question 3

What are the features of directional selection? Give an example.

Answer 3

• when one of the extreme traits has the selective advantage
• occurs when there’s a change in the environment
• the modal trait is what changes

E.g. antibiotic resistance in bacteria

Question 4

Give the features if stabilising selection and give an example.

Answer 4

-the modal traits have a selective advantage
-occurs when there’s no change in the environment
-the modal trait here remains the same
- Standard deviation decreases as individuals with the extreme trait decrease
E.g. human birth weight

Question 5

What is genetic diversity?

Answer 5

The number of different alleles of genes in a population

Question 6

What does genetic diversity allow to occur?

Answer 6

Natural selection

Question 7

How does antibiotic resistance happen?

Answer 7

1. The antibiotic is the selective pressure of the bacteria
2. Genetic variation in the gene pool triggers random mutation
3. Individuals with the mutation that causes resistance triggers selective advantage
4. This increases their likelihood of survival so increases likelihood of reproduction and passing on the advantageous mutation
5. This causes a decrease in the bacteria not resistant to the antibiotic and hence increase frequency of resistance