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Question
A potted plant was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours. One of the leaves was covered with black paper in the centre. The potted plant was then placed in sunlight for a few hours.
Why was the plant placed in the dark before beginning the experiment?
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Solution
Before beginning the experiment, the plant was kept in dark in order to destarch it, i.e. to remove the pre-existing starch from the storage organs.
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The diagram alongside refers to an experiment in which the apparatus was set up with the light source 10 cm away from the plant. After 15 minutes the number of bubbles evolved per minute from the cut stem was recorded. The light source was moved to 20 cm away from the plant, left for 15 minutes and the number of bubbles evolved per minute was again recorded. The experiment was repeated with the light source at distances of 40, 60, 80 and 100 cm away from the plant. Plot a graph for the results obtained and answer the following questions.
(i) From the graph it seems likely that the rate of bubbling per minute at 50 cm would have been
(a) 2.0 (b) 2.5 (c) 3.0 (d) 3.5
(ii) The gas produced by the plant during the experiment was
(a) air (b) oxygen (c) carbon dioxide (d) nitrogen (e) hydrogen
(iii) The gas collected comes due to the breakdown of
(a) glucose (b) starch (c) water (d) air (e) ATP
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(b) Increase because more water is added.
(c) Decrease because the temperature drops.
(d) Decrease because water freezes.
(e) Cannot tell from the information given.
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(a) Increases because more respiration occurs.
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(c) Increases because the gas becomes less soluble.
(d) Decreases because carbon dioxide acts as a limiting factor.
(e) Decreases because respiration decreases.
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Photosynthesis in green plants is directly and indirectly dependent on so many plant structures.
Explain briefly the role of the following structures in this process is Cuticle.
Given below is a schematic diagram to illustrate some aspects of photosynthesis.
- Fill up the gaps, in blank spaces (1-4), by writing the names of the correct items.
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Given below is the representation of a certain phenomenon in nature. With four organisms 1-4.
- Name the phenomenon represented.
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A potted plant was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours. One of the leaves was covered with black paper in the centre. The potted plant was then placed in sunlight for a few hours.
During the starch test, why was the leaf
(1) boiled in water
(2) boiled in methylated spirit
Differentiate Between:
Light reaction and Dark reaction.
Name the following:
The site of light reaction in the cell of a leaf.
Match the terms given in column A with column B:
| Column A | Column B | ||
| (a) | Chlorophyll | (i) | Removes/absorbs CO2 |
| (b) | Methylated spirit | (ii) | Tests presence of starch |
| (c) | Potassium hydroxide | (iii) | Traps solar energy |
| (d) | Iodine solution | (iv) | Produces oxygen |
| (e) | Water | (v) | Bleaches chlorophyll |
Give reasons/explain:
During the starch test, the leaf is boiled in methylated spirit.
