3.2

Question 1

what is Stabilising Selection

Answer 1

Occurs when a particular phenotype coincides with optimal conditions
e.g. eggs, a larger number of eggs = malnourished chicks, smaller number = no viable offspring, 4 egg perfect

Question 2

what is Directional Selection

Answer 2

Occurs with gradually changing environments

e.g. moth colour

Question 3

what is Disruptive/Diversifying Selection

Answer 3

Occurs when fluctuating conditions favour the presence of more than one phenotype.
e.g. rabbit colours are white and grey and grey is better suited to a rocky environment than fully white.

Question 4

what is gene flow

Answer 4

Gene flow is the transfer of genes between populations. Restricting gene flow results in speciation or in very fragmented populations, and lower genetic diversity.

Question 5

explain what the term ‘genetic drift’ means.

Answer 5

Genetic drift is a mechanism of evolution characterized by random fluctuations in the frequency of a particular version of a gene (allele) in a population.

Question 6

what is the Bottleneck effect

Answer 6

A bottleneck effect is when there is a very noticeable reduction in population size for a minimum of one generation time.

Question 7

what is the Founder effect

Answer 7

A founder effect is when a few individuals move to a new region and start a new colony of limited genetic variation

Question 8

Explain the difference between abiotic and biotic factors

Answer 8

The biotic factors refer to all the living beings present in an ecosystem, and the abiotic factors refer to all the non-living components like physical conditions (temperature, pH, humidity, salinity, sunlight, etc.) and chemical agents (different gases and mineral nutrients present in the air, water, soil, etc.)