AQA GCSE Biology

Inheritance & Punnett squares

AQA GCSE Biology revision on Inheritance & Punnett squares. Aligned to the AQA GCSE Biology 8461 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Why does a homozygous recessive individual only express the recessive phenotype?

    • A) They carry two dominant alleles
    • B) No dominant allele is present
    • C) The recessive allele is stronger
    • D) Both alleles are mutated genes
    Show answer

    Answer: No dominant allele is present

    A dominant allele will always express its characteristic if present in the genotype. Therefore, the recessive phenotype can only be observed when an individual inherits two recessive alleles, meaning no dominant allele is available to override the recessive trait.

  2. Question 2

    Which term describes the physical appearance of an organism resulting from its inherited alleles?

    • A) Genotype
    • B) Phenotype
    • C) Gamete
    • D) Mutation
    Show answer

    Answer: Phenotype

    The genotype is the specific genetic makeup or set of alleles an organism possesses. In contrast, the phenotype refers to the observable physical or biochemical characteristics, which are determined by the interaction between the genotype and the environment.

  3. Question 3

    What is the probability of a heterozygous parent and a homozygous recessive parent producing an offspring that is homozygous recessive?

    • A) Twenty-five percent chance
    • B) Fifty percent probability
    • C) Seventy-five percent odds
    • D) One hundred percent chance
    Show answer

    Answer: Fifty percent probability

    When crossing a heterozygous individual (Aa) with a homozygous recessive individual (aa), the possible offspring are Aa, aa, Aa, and aa. This results in a 50% chance for the genotype to be heterozygous and a 50% chance for it to be homozygous recessive.

Want to test yourself on the remaining cards for this topic?

22 more questions on Inheritance & Punnett squares — plus mistakes tracking and spaced repetition across the whole Biology spec.

Start a free session → Already have an account? Log in

More AQA Biology topics