3.4.4 - Genetic diversity and adaptation

Question 1

Define genetic diversity - explain how genetic diversity enables natural selection

Answer 1

the number of different alleles of genes in a population - enables natural selection to occur - more genetic diversity = more likely some individuals in the population will survive environmental change

Question 2

Explain how reproductive success impacts allele frequency in a gene pool ?

Answer 2

1. gene pool contains a large frequency of alleles
   2.** random mutations result in new alleles **of a gene
2. depending on the environment this could be beneficial - individuals more likely to outcompete others for resources
3. higher chance of successfully reproducing and passing alleles to the next generation -** so advantageous allele is most likely to be passed on**
4. over many generations the number of individuals with the advantageous allele will increase -** increases in frequency**

Question 3

Define selection

Answer 3

organisms that are best adapted to their environment will survive and breed - different environmental conditions favour different characteristics

Question 4

Define directional selection

Answer 4

favours individuals at the extremes (phenotype at one extreme is selected for)
- changes the overall characteristics of the population
- occurs when environmental conditions change

Question 5

Define stabilising selection

Answer 5

favours average individuals (phenotypes around the mean are selected for and those at both extremes are selected against)
- preserves characteristics of the population
- occurs when environmental conditions remain stable

Question 6

How do bacteria show directional selection?

Answer 6

1. mutation occurs in the allele of a bacteria - new protein is able to break down the antibiotic penicilin
   2.** bacteria with the mutation is able to survive** while the rest die
2. bacteria divides by** binary fission **- more resistant bacteria
3. frequency of the mutated allele increased
4. **normal distribution shifted **in the direction of increased penicilin resistance

Question 7

Give three types of adaptations an organism can aquire to increase chances of survival

Answer 7

• anatomical
• physiological
• behavioural