Edexcel GCSE Biology

Variation, evolution & classification

Edexcel GCSE Biology revision on Variation, evolution & classification. Aligned to the Pearson Edexcel GCSE Biology 1BI0 specification. This bank has 25 practice questions on this topic.

Sample questions (3 of 25)

  1. Question 1

    Variation in a species comes from...

    • A) Genetic causes only
    • B) Environmental causes only
    • C) Both genetic + environmental causes
    • D) Magic
    Show answer

    Answer: Both genetic + environmental causes

    Genetic variation: comes from MUTATIONS (random changes in DNA) + SEXUAL REPRODUCTION (mixing parental DNA, independent assortment, crossing-over). Environmental variation: diet, exercise, scars, accents. Most traits = both. Identical twins have same genes but turn out slightly different - environment matters.

  2. Question 2

    Charles Darwin's theory of evolution by natural selection states that...

    • A) All species are unrelated
    • B) Individuals best adapted to their environment survive + reproduce, passing on their genes
    • C) Strongest animals always win
    • D) Species don't change
    Show answer

    Answer: Individuals best adapted to their environment survive + reproduce, passing on their genes

    Darwin's 4 key points: (1) Individuals VARY (within a species). (2) MORE offspring than environment can support. (3) Those with USEFUL variations are MORE LIKELY to survive + reproduce. (4) They pass on the useful traits. Over many generations, the useful traits become more common -> species changes. 'Survival of the fittest' is misleading - fittest means 'most adapted', not 'strongest'.

  3. Question 3

    Selective breeding is when humans...

    • A) Cross-breed any animals randomly
    • B) Choose individuals with desirable traits + breed them together over generations
    • C) Genetically modify animals
    • D) Buy pedigree dogs
    Show answer

    Answer: Choose individuals with desirable traits + breed them together over generations

    Examples: dairy cows bred for high milk yield, wheat for big grains + disease resistance, dogs for specific breeds. Pros: faster than natural selection, useful traits. Cons: reduced gene pool (inbreeding), genetic disorders more common, less resilient to disease. Genetic engineering = next step (direct DNA modification).

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