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5.1 Inheritance

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Question 23
H

Siamese cats have pale fur on most of their body and dark fur on their ears, face, paws and tail.

  • The dark pigment in fur is made by an enzyme.
  • Siamese cats have a variant of the gene for this enzyme.
  • The enzyme made from this variant is inactive at temperatures above about 33 ∘C33\ ^\circ\text{C}33 ∘C.
  • The ears, face, paws and tail are cooler than the rest of the body.
  • When fur is shaved from a Siamese cat's body and an ice pack is kept on the skin, the fur grows back dark.

Explain how the genome and the environment interact to produce the fur pattern of a Siamese cat.

In your answer, include how the variant arose and how it affects the enzyme.

[6]
Markscheme

5.1 Inheritance Questions

  1. GCSE
  2. /Biology
  3. /5.1 Inheritance

186 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.

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