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Patterns of inheritance

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Question 19

Two characteristics in flour beetles (Tribolium castaneum) are body colour and antenna shape.

Body colour is determined by a gene with two alleles:

  • Allele B\text{B}B is dominant and results in a black body.
  • Allele b\text{b}b is recessive and results in a grey body.

Antenna shape is determined by a gene with two alleles:

  • Allele A\text{A}A is dominant and results in clubbed antennae.
  • Allele a\text{a}a is recessive and results in filamentous antennae.

The two genes are located on different chromosomes.

Two beetles are crossed:

  • One parent beetle has a black body and clubbed antennae, and is heterozygous for both genes.
  • One parent beetle has a black body and filamentous antennae, and is heterozygous for the B/b\text{B/b}B/b gene.

Complete the following details to show this genetic cross:

a.

Parental genotypes

[1]
b.

Gametes

[1]
c.

Expected offspring phenotypes

[1]
d.

Expected phenotypic ratio

[1]
Markscheme

Patterns of inheritance Questions

  1. A Level
  2. /Biology
  3. /Patterns of inheritance

32 exam-style questions on OCR A A Level Biology Patterns of inheritance. Each one has a worked solution and a mark scheme showing where the marks go.

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