Inheritance

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Question 16
Medium

Achromatopsia is an inherited eye condition.

It is caused by a gene mutation that produces a recessive allele.

The condition causes cone cells in the retina to become damaged or non-functional.

a.

Explain the meaning of these genetic terms:

  • Genotype
  • Phenotype
[2]
b.

Two parents who are heterozygous for achromatopsia are expecting a child. Draw a genetic diagram to calculate the probability that the child will have the condition. Use A A\,A for the normal allele and a a\,a for the allele for achromatopsia.

[3]
c.

Individuals with complete achromatopsia have normal vision in dim light but cannot perceive colours. Explain why.

[2]
d.

Explain why stem cells could be used as a treatment for this condition.

[2]
e.

Why is it an advantage to use stem cells harvested from the patient rather than from another person?

[2]

Inheritance Questions

  1. GCSE
  2. /Biology
  3. /Inheritance