Topic 8

Question 1

Explain why in areas with low populations of orangutans, many of the orangutans have
deformities and health problems.

Answer 1

Genetic bottleneck Genetic diversity is lowered, increasing recessive allele frequency in both parents.

Question 2

Pure breeding

Answer 2

homozygous for both alleles eg AABB or aabb

Question 3

Explain the difference between the expected ratio and the number shown in the table.

Answer 3

Genes BR and br are linked and are carried on the same chromosome, like BbRr. Other phenotypes like Bbrr, BBrr (black smooth) and white rough (bbRr or bbRR) have come about through crossing over and recombination.

Question 4

codominant alleles

Answer 4

Both alleles are expressed / shown (in the phenotype).

Question 5

one gene two alleles

Answer 5

monohybrid cross

Question 6

two genes two alleles

Answer 6

dihybrid cross