Gibberellins are plant hormones with several commercial uses. Explain how gibberellins can be used commercially to produce seedless grapes.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Growers can treat grape flowers with gibberellins before fertilisation occurs. The resulting grapes develop without seeds and are larger than untreated grapes.
Model answer (4 marks)
Gibberellins are applied to grape flowers before fertilisation. They stimulate the ovary to grow and develop into fruit even though no pollen has fertilised the ovules. Because fertilisation does not occur, the ovules do not develop into seeds, so the fruit is seedless. Gibberellins also promote cell division and elongation in the fruit, making it larger than untreated fruit. The result is a larger, seedless grape that is more attractive to consumers and therefore has commercial value.
Examiner tips
- Use the word ‘stimulate’ for the hormone’s action on fruit development and cell growth.
- Explain that lack of fertilisation means no seed formation.
- Mention the commercial benefit of larger, seedless fruit.
- Keep the answer concise and use the exact terminology from the mark scheme.
Common mistakes
- Confusing fertilisation with pollination; students say the flowers are pollinated instead of fertilised.
- Failing to state that the fruit is larger, only mentioning seedlessness.
- Using vague terms like ‘helps fruit grow’ instead of ‘stimulates cell division and elongation’.
Mark scheme (4 marks)
- Gibberellins stimulate fruit formation / development of the fruit without fertilisation occurring
- Because no fertilisation occurs, no seeds are produced inside the fruit
- Gibberellins also regulate / stimulate cell growth / elongation so the fruit grows larger
- This has a commercial benefit because seedless, larger fruit is more appealing / sells better / is easier for consumers to eat
Key terms in this question
Related
- Revision notes: Plant hormones →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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