Genes & Inheritance 2

Question 1

Define allele.

Answer 1

Different forms of a gene.

Question 2

Define heterogeneous and homogeneous.

Answer 2

Heterogeneous - homologous chromosomes carry different alleles of a gene.
Homogeneous - homologous chromosomes carry the same alleles of a gene.

Question 3

Define additive alleles.

Answer 3

alleles are not completely dominant or recessive - their effects blend together or mix.

Question 4

Define co-dominance alleles.

Answer 4

Co-dominant alleles are ones whose effects can both be seen together in the phenotype e.g. human ABO blood group system.

Question 5

Define polygenic inheritance.

Answer 5

Traits are influences by several genes together.

Question 6

Define penetrance.

Answer 6

The proportion of individuals carrying the allele that actually show in the phenotype

Question 7

Define epistasis.

Answer 7

When the expression of a gene can be conditional on the allele of another gene.