Question

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(i) Cover the middle part of a healthy leaf with strips of black paper and fasten it with clips.

(ii) Keep the potted plant under bright sunshine.

(iii) Destarch the potted plant.

The correct sequence of procedure for experiment to study light is essential for photosynthesis should be?

• A. (i), (ii), (iii)
• B. (ii), (i), (iii)
• C. (iii), (i), (ii)
• D. (i), (iii), (ii)

Answer 1

The correct option is C

(iii), (i), (ii)

The correct option is (C)

Explanation for the correct option:

1. To study the importance of light for photosynthesis, an experiment with black paper strips can be conducted.
2. The sequence of steps for the experiment includes; placing the plant in the dark for destarch, covering the leaves at some places with black paper strips, and placing the plant in sunlight.
3. Covering the leaves leads to no photosynthesis in those regions due to the absence of sunlight.
4. The uncovered regions of the leaves receive sunlight and produce starch by photosynthesis.
5. Iodine, when added to the leaves, will turn the uncovered regions blue-black due to the reaction with starch.
6. The covered regions do not change color due to the absence of starch.
7. Thus, sunlight is essential to conduct photosynthesis.

Explanation for incorrect options:

Option (A)

1. To know whether sunlight will lead to the starch formation in leaves, the stored starch from the plant should be removed. This is called destarching.
2. Thus, destarching the plant is the first step in the experiment to study the light effect in photosynthesis.

Option (B)

1. After destarching, the plant leaves are covered with black paper strips using clips.
2. Thus, covering the leaves with black paper is the second step.

Option (D)

1. After covering the leaf areas with black paper strips, the plant is kept under sunlight.
2. Thus, placing the plant in the Sun is the third step.

The correct sequence of steps is; placing the plant in the dark for destarch, covering the leaves at dome places with black paper strips, and placing the plant in sunlight.