A population of aphids (small insects) reproduces asexually during summer when food is plentiful, but switches to sexual reproduction in autumn when conditions become harsh. Explain why asexual reproduction is beneficial during summer but why the population is at risk if it relies only on asexual reproduction.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Asexual reproduction allows rapid production of large numbers of offspring, which is beneficial when conditions are favourable.
It takes less energy and is more efficient than sexual reproduction.
All offspring are genetically identical, so a single pathogen or disease can destroy the entire population.
Because the offspring are clones, they cannot adapt to environmental changes, so if conditions become harsh the population may not survive.
It takes less energy and is more efficient than sexual reproduction.
All offspring are genetically identical, so a single pathogen or disease can destroy the entire population.
Because the offspring are clones, they cannot adapt to environmental changes, so if conditions become harsh the population may not survive.
Examiner tips
- Use the exact wording from the mark scheme; mention rapid production, energy efficiency, genetic identity, and vulnerability to disease and change.
- Show the link between favourable conditions and rapid growth, and between harsh conditions and lack of variation.
Common mistakes
- Mixing up the benefits of sexual reproduction; forgetting to mention energy efficiency.
- Failing to state that identical offspring cannot adapt to change.
Mark scheme (4 marks)
- Asexual reproduction allows rapid production of large numbers of offspring, which is beneficial when conditions are favourable
- Asexual reproduction takes less energy / is more efficient than sexual reproduction
- All offspring are genetically identical / clones, so a single pathogen or disease can destroy the entire population
- Genetically identical offspring cannot adapt to environmental changes, so if conditions become harsh the population may not survive
Key terms in this question
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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