Plant responses to signals — A/L Biology

How do I practise Plant responses to signals?

1 question with a worked solution

1. Which plant hormone is primarily responsible for inducing stomatal closure during severe drought stress to prevent water loss?
   1. A) Abscisic acid (ABA)
   2. B) Gibberellin (GA₃)
   3. C) Cytokinin
   4. D) Auxin (IAA)
   Check my answer

   Correct answer: A) Abscisic acid (ABA)

   Abscisic acid (ABA) is the major stress hormone synthesized in roots and leaves in response to water deficit; it triggers potassium and anion efflux from guard cells, decreasing turgor and closing stomata.

   Show worked solution

   Step 1: Identify functions of plant hormones: - Auxins promote cell elongation and apical dominance. - Gibberellins promote stem elongation and seed germination. - Cytokinins stimulate cell division. - Abscisic acid acts as stress response signal for stomatal closure. Answer: Abscisic acid (ABA).
   Modelled on: the A/L Biology examination pattern

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Where does Plant responses to signals fit in the syllabus?

Year 1 · Term 3