Explain how sexual reproduction produces offspring with greater genetic variation than asexual reproduction.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Sexual reproduction involves the fusion of two gametes (fertilisation) – two parents contribute genetic material.
Gametes each contain half the chromosome number, so each parent contributes one allele from each pair.
The combination of alleles from both parents gives the offspring a unique genotype, producing variation in phenotype.
Asexual reproduction uses only one parent and produces genetically identical offspring (clones), so there is no variation in genotype.
Gametes each contain half the chromosome number, so each parent contributes one allele from each pair.
The combination of alleles from both parents gives the offspring a unique genotype, producing variation in phenotype.
Asexual reproduction uses only one parent and produces genetically identical offspring (clones), so there is no variation in genotype.
Examiner tips
- Use the word ‘fusion’ or ‘fertilisation’ to show you know the process.
- Mention ‘half the chromosome number’ to justify allele mixing.
- Show that the offspring’s genotype is unique, linking to phenotype variation.
- Contrast with asexual reproduction producing clones.
Mark scheme (4 marks)
- Sexual reproduction involves the fusion of two gametes (fertilisation) / two parents contribute genetic material
- Gametes each contain half the chromosome number / one allele from each pair, so offspring receive a different combination of alleles from each parent
- This means offspring have a unique combination of alleles / genotype, leading to variation in phenotype
- Asexual reproduction involves only one parent and produces genetically identical offspring (clones), so there is no variation in genotype
Key terms in this question
sexual reproduction · asexual reproduction
Related
- All WJEC GCSE Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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