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प्रश्न
Two healthy green plants were placed in the dark for 24 hours. They were then set up, as shown in the figure, for 4 hours. Then a leaf was taken from each plant and
the chlorophyll was removed from the leaves:
( i) What is the next and final step in this experiment?
( ii ) What would be the results of the final step?
( iii ) Why was it necessary to grease the glass sheet?
( iv ) What hypothesis is being tested in this experiment?
उत्तर
(i) The leaf is then treated with iodine solution.
(ii) The leaf from first plant will not show starch test while the leaf from second plant will become blue-black showing the presence of starch.
(iii) It is necessary to grease the glass sheet to prevent the entry of air containing CO2.
(iv) The hypothesis that CO2 is necessary for photosynthesis is being tested in this experiment.
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संबंधित प्रश्न
An experiment was set up as shown in the figure given below . The twig in the diagram was intact on the plant and it was as such in sunlight for a few hours .
(i) What is the aim of the above experiment ?
(ii) Why was potassium hydroxide placed inside the conical flask ?
(iii) What test would you perform on the leaf inside the flask?
(iv) What is the expected result of the above test ?
(v) Is it necessary to similarly test on outer leaf also ? Giva a reason .
Fill in the blank:
Land plants obtain their carbon dioxide from the ______.
Name the following:
The source of carbon dioxide for aquatic plants.
Why is it not possible to demonstrate respiration in a green plant kept in sunlight?
All life owes its existence to chlorophyll. Give reason.
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.
Draw a neat diagram of a chloroplast and label its parts.
Write the overall chemical equation for photosynthesis.
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.
Given below is the diagram of an experimental set-up (final stage). Study the same and answer the following questions:
- What is the main aim of the experiment?
- Oxygen gas shown in the experiment is released from which of the raw materials?
- How would you confirm the presence of oxygen gas?
- Name the chemical substance which can be added in water to enhance the process/rate of release of oxygen gas.
- Draw a neat and labelled diagram of the same experiment for its initial stage.
