A population of strawberry plants reproduces asexually by sending out runners that produce new plants. A fungal disease infects one plant in the population. Explain why this disease is likely to destroy the entire population.

Cambridge International IGCSE Biology (0610) — 16.1 Asexual reproduction · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

All offspring are genetically identical (clones) to the parent plant
Therefore all plants have the same lack of resistance / susceptibility to the disease
There is no genetic variation / diversity in the population
So a pathogen / disease that harms one individual will harm all individuals, potentially destroying the whole population

Examiner tips

  • Use the word ‘because’ to link cause and effect clearly
  • Show the chain of reasoning: clone → no variation → same susceptibility → disease spreads to all

Common mistakes

  • Failing to mention that all plants are clones
  • Omitting the link between lack of variation and disease spread

Mark scheme (4 marks)

  1. All offspring are genetically identical (clones) to the parent plant
  2. Therefore all plants have the same lack of resistance / susceptibility to the disease
  3. There is no genetic variation / diversity in the population
  4. So a pathogen / disease that harms one individual will harm all individuals, potentially destroying the whole population

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