Variation, Selection & Evolution - exam practice

Selection pressure can affect homozygous individuals. The effect can be investigated using a model gene pool.

Why is a large gene pool necessary?

A number of events occur for a new species to emerge in a population.

Which statement(s) correspond(s) to events that are involved in the formation of a new species?

1 - gene mutation

2 - selection pressure

3 - a change in the environment

The adult wandering albatross, Diomedea exulans, has wingspans that range from 2.5 m to 3.5 m.

What describes the variation in wingspan of the wandering albatross?

What is not associated with the use of artificial selection in farm animals?

The ability to roll one’s tongue is under the control of a single gene. The gene has two alleles R and r.

People who can roll their tongues can have the genotypes RR or Rr. People who cannot roll their tongues have the genotype rr.

A survey by a student showed that 12% of the population in a single school cannot roll their tongues.

The student then used the Hardy-Weinberg principle to calculate the number of heterozygous individuals in the school.

What is the percentage of heterozygous individuals at the student’s school?

Use the equations: p + q = 1 and p² +2pq + q² = 1

The two histograms represent the frequency distribution for the two different types of variation.

Which statement about characteristic Q is correct?

There are four different human blood groups: A, B, AB, and O.

This is because there are three different alleles coding for different proteins in red blood cells.

What describes this form of variation?

What is the likely outcome when a mutation results in a trait that improves an organism's survival and reproduction?

What does stabilising selection typically do to a population's characteristics?

What are characteristics that are influenced by more than one gene are called?

Which type of selection favours individuals that vary in one direction from the mean of the characteristic?

What type of selection could lead to antibiotic resistance in bacteria?

What is an example of a characteristic that may be selected for by directional selection in a changing environment?

What change occurs in a population's normal distribution curve during directional selection?

What is/are the primary source(s) of genetic variation in sexually reproducing organisms?

What type of selection favours phenotypes that vary in one direction from the mean of the population?

What does disruptive selection typically result in?

What describes the situation when two distinct forms of a species survive and reproduce more successfully than intermediates?

Which process results in allopatric speciation?

Which process directly results in sympatric speciation?