ib biology 10.2 polygenic inheritance

Pea seeds can be either green or yellow. It is reasonable to suggest that seed colour is

• an example of polygenic inheritance.

• determined by the combination of alleles for a single gene.

• an example of continuous variation.

• due to the effect of multiple alleles.

The image shows variation in human height. What can explain the variation?

• one pair of alleles and age

• polygenic inheritance and nutrition

• nutrition and age

• autosomal inheritance only

The graph shows the frequencies of blood type in an isolated Alaskan population. From the graph is it reasonable to conclude that

• B blood type must be recessive

• blood type comes in three phenotypes

• blood type must be controlled by two different genes

• blood type is an example of discrete variation

Polygenic inheritance

• involves a single gene that has more than two different alleles.

• is responsible for a limited number of phenotypes.

• tends to show continuous variation.

• is only found in humans.

Fur colour is controlled by a single gene with a dominant allele B (black) and a recessive allele b (brown). The number of possible genotypes and phenotypes respectively is

• 2 and 3

• 3 and 3

• 3 and 2

• 2 and 2