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Inheritance

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Question 26

The flower colour of a particular species of plant is determined by a single gene with three alleles that show codominance and simple dominance.

The table below shows the different flower phenotypes and their genotypes:

Flower phenotypeGenotypes
RedCRCR C^R C^R\,CRCR or CRCWC^R C^WCRCW
BlueCBCB C^B C^B\,CBCB or CBCWC^B C^WCBCW
PurpleCRCBC^R C^BCRCB
WhiteCWCWC^W C^WCWCW
a.

Explain what is meant by the term codominance.

[2]
b.

A cross between a red-flowered plant and a blue-flowered plant produces some offspring with white flowers. Use a genetic diagram to show how this is possible. Your diagram should include:

  • Genotypes of the parents
  • Gametes produced by each parent
  • Genotypes of the potential offspring, and their corresponding phenotypes.
[4]

Inheritance Questions

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