Question 29 – Patterns of inheritance - Questions

In primroses ( $P r im u l a s in e n s i s$ ), flower colour is controlled by two genes, $D / d$ and $B / b$ .

The dominant allele, $D$ , suppresses the synthesis of anthocyanin pigment, resulting in white flowers.
The recessive allele, $d$ , allows pigment synthesis to occur so the flowers develop colour.
The dominant allele, $B$ , controls the production of blue pigment.
Primrose plants homozygous for the recessive allele, $b$ , produce red pigment (in the absence of the dominant inhibiting allele).

A white-flowered primrose plant was cross-pollinated with a blue-flowered primrose plant. All resulting offspring had the genotype $D d B b$ .

Identify the following:

State the type of gene interaction shown by the genes $D / d$ and $B / b$ .

Suggest how the dominant allele $D$ inhibits the expression of allele $B$ .

In primroses ( $P r im u l a s in e n s i s$ ), flower colour is controlled by two genes, $D / d$ and $B / b$ .

The dominant allele, $D$ , suppresses the synthesis of anthocyanin pigment, resulting in white flowers.
The recessive allele, $d$ , allows pigment synthesis to occur so the flowers develop colour.
The dominant allele, $B$ , controls the production of blue pigment.
Primrose plants homozygous for the recessive allele, $b$ , produce red pigment (in the absence of the dominant inhibiting allele).

A white-flowered primrose plant was cross-pollinated with a blue-flowered primrose plant. All resulting offspring had the genotype $D d B b$ .

Identify the following:

State the type of gene interaction shown by the genes $D / d$ and $B / b$ .

Suggest how the dominant allele $D$ inhibits the expression of allele $B$ .

Patterns of inheritance