Module 4 : Natural selection

Question 1

What are selection pressures?

Organisms that are …

Answer 1

environmental factors that affect the survival and reproduction of organisms

best adapted to certain selection pressures are more likely to survive and pass on their adaptive traits to future generations

Question 2

An allele is …

Different alleles can result in what?

Answer 2

a different version (variant) of a gene

different observable traits

Question 3

What is genetic diversity a measure of?

Describe how genetic diversity influences natural selection (2 points)

Answer 3

the total number of different alleles in a population

organisms with advantageous alleles are more likely to survive , reproduce and pass on their alleles to offspring , influencing the gene pool
the more successful an organism is at reproducing , the more likely its alleles will be passed on , increasing the allele frequency

Question 4

Describe the 5 key steps in natural selection

Answer 4

1)there is variation in characteristics within a species
2)more genetic variation emerges in a population due to random mutations
3)individuals with alleles coding for traits that are advantageous for survival are more likely to reproduce
4)these advantageous alleles are passed onto offspring
5)overtime these alleles become more common in the population

Question 5

What are 2 modern examples of evolution by natural selection?

Answer 5

antibiotic resistant bacteria
pesticide resistant insects

Question 6

Make 4 points describing how antibiotic resistance emerges through natural selection

Answer 6

1)some bacteria develop random mutations that lead to resistance
2)when antibiotics are used , only resistant ones survive
3)resistant bacteria reproduce , passing on their resistant alleles to offspring
4)overtime the proportion of resistant alleles increases , leading to mostly resistant bacteria

Question 7

Make 4 points describing how pesticide resistance emerges through natural selection

Answer 7

1)some insects randomly mutate which provides resistance to pesticides , so only resistant insects survive while majority are killed
2)resistant insects reproduce , passing on their resistant alleles
3)frequency of resistant alleles increases over generations , increasing the populations overall resistance
4)eventually the pest population evolves to a point where the pesticide is no longer effective