SB3i Multiple And Missing Alleles

Question 1

ABO blood group

Answer 1

Blood group system in humans which produces four phenotypes: blood groups A, B, AB and O.

Question 2

Carrier

Answer 2

An individual that has inherited a recessive allele but does not show the phenotype caused by that allele. For example, a woman who has one allele for a sex-linked genetic disorder and one ‘healthy’ allele will not suffer from the disorder but can pass it on to a son.

Question 3

Codominant

Answer 3

Two alleles that both affect the phenotype. For example a person with the blood group alleles IA and IB has blood group AB.

Question 4

Sex-linked genetic disorder

Answer 4

A disorder caused by genes that are inherited differently in males and females because they are carried on the sex chromosomes. An example is red–green colour blindness, which is more common in men than in women.