Experiment: To examine phototropism, seedlings were grown with a unidirectional light source. One set had light from above; another from the side.Observation: Seedlings with side light bent toward the light source, while vertical light resulted in straight growth.Question: What can be concluded?
Correct answer: C. Auxins accumulate on the shaded side, causing cell elongation.
- A. Light destroys hormones on the light-facing side.
- B. Plants always grow straight regardless of light direction.
- C. Auxins accumulate on the shaded side, causing cell elongation.
- D. Light inhibits all types of plant growth.
Explanation
In the experiment described, the observation that seedlings with side light bent towards the light source indicates phototropism, a plant's response to light. This response is mediated by the hormone auxin, which accumulates on the shaded side of the plant, causing cell elongation and bending towards the light. Option A and B are incorrect as they do not explain the observed phenomenon. Option D is incorrect as light does not inhibit all types of plant growth, only specific responses like phototropism.
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About Scientific Reasoning
Scientific reasoning evaluates hypotheses through observations, variables, controls, measurements and experimental results. Questions involve identifying independent and dependent variables, recognising a fair test, interpreting tables or graphs, distinguishing evidence from opinion, and deciding whether data supports, rejects or leaves a hypothesis unresolved.
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