A-Level UK (AQA, Edexcel, OCR) · Biology

Genetics and variation

8 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 8 questions

  1. In a population in Hardy-Weinberg equilibrium, 4% of people have a recessive condition. What percentage are carriers?
  2. Two parents are both heterozygous carriers of cystic fibrosis (Ff). What is the probability that a child is an unaffected carrier?
  3. A woman who is a carrier for haemophilia (X-linked recessive) has children with an unaffected man. What is the probability that a son has haemophilia?
  4. A man with blood group A (genotype I^A I^O) and a woman with group B (I^B I^O) have a child. What is the probability that the child has group O?
  5. A monohybrid cross produces 200 offspring: 160 with the dominant phenotype and 40 with the recessive. A 3:1 ratio is expected. What is the chi-squared value and conclusion at p = 0.05 (critical value…
  6. Which two processes in meiosis produce genetic variation between gametes?
  7. A cross between two heterozygous individuals (AaBb x AaBb) produces 160 offspring. How many are expected to show both recessive characteristics (aabb) if the genes assort independently?
  8. The deletion of a single base from the middle of a gene is likely to have a more severe effect than a base substitution. Why?

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