Plant Responses Quiz - CBSE Class 12 Biology

Free practice quiz: Plant Responses (CBSE Class 12 Biology). 20 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. Which plant hormone primarily mediates the phototropic response?

   1. Auxin
   2. Gibberellin
   3. Cytokinin
   4. Abscisic acid
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   Answer: A. Auxin

   Auxin accumulates on the shaded side of a plant stem, promoting cell elongation and causing the stem to bend towards the light source.

2. How does the concentration of auxin influence the direction of plant growth in phototropism?

   1. Higher concentration on shaded side causes bending towards light
   2. Higher concentration on illuminated side causes bending towards light
   3. Equal concentration on both sides causes no bending
   4. Concentration is irrelevant to bending
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   Answer: A. Higher concentration on shaded side causes bending towards light

   The higher concentration of auxin on the shaded side stimulates cell elongation, causing the plant to bend towards the light source.

3. Describe the phenomenon of nastic movements in plants and provide an example.

   1. Growth response to light
   2. Growth response to gravity
   3. Non-directional response to stimuli
   4. Growth response to touch
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   Answer: C. Non-directional response to stimuli

   Nastic movements are non-directional responses to stimuli, such as the opening and closing of mimosa leaves in response to touch.

4. Compare and contrast the mechanisms of action of different plant hormones in regulating plant responses to environmental cues.

   1. All plant hormones have identical mechanisms
   2. Mechanisms are similar for all hormones
   3. Mechanisms are unique to each hormone, but show similarities
   4. Mechanisms are entirely different for all hormones
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   Answer: C. Mechanisms are unique to each hormone, but show similarities

   While each plant hormone has a unique primary mechanism of action, there are often overlaps and interactions between their signaling pathways.

5. Design an experiment to investigate the role of a specific plant hormone in mediating a particular plant response. Include details on experimental design, controls, and data analysis.

   1. No suitable design possible
   2. A simple design suffices
   3. A complex multifactorial design is necessary
   4. Any design will suffice
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   Answer: C. A complex multifactorial design is necessary

   Investigating hormone roles requires careful experimental design to control for confounding factors and accurately measure the effects of the hormone.

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