Lesson 2 - Natural selection in action

Question 1

meaning industrial melanism

Answer 1

the evolution of dark-coloured individuals in a habitat that has been made darker by industrial pollution e.g. soot

Question 2

meaning selection pressure

Answer 2

the pressure exerted by a changed environment or niche on individuals in a population, causing changes in the population as a result of natural selection

Question 3

meaning directional selection

Answer 3

the natural selection showing a change from on dominant phenotype to another in response to a change in the environment

Question 4

meaning gene pool

Answer 4

all of the alleles of all of the genes in a population

Question 5

explain the process of natural selection

Answer 5

if the niche occupied by an organism changes due to changes in environment, different characteristics may make an individual more successful. Natural selection will favour the survival of individuals with those different characteristics, so the selection pressure has changed. This results in evolution within a species, eventually resulting in speciation.

Question 6

explain the natural selection of the black peppered moths during the industrial revolution

Answer 6

Before the industrial revolution, selection pressure meant that the frequency of the dark allele in the population of the black peppered moth remained low. This was because black moths were more visible against the white tree barks, thus didn’t have enough time to reproduce.
During the industrial revolution, soot from the factories coloured the tree barks black. As a result, the black moths were at a selective advantage, thus were able to pass on their advantageous alleles and increased in frequency.