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प्रश्न
How does carbon dioxide return to the atmosphere? Explain.
A student in order to study the importance of certain factors of photosynthesis took a potted plant and kept it in the dark for over 24 hours. Then in the early hours of the morning the student covered one of the leaves with black paper in the centre only. Student placed the potted plant in the sunlight for a few hours, and then tested the leaf which was covered with black paper for starch.
(i) What aspect of photosynthesis was being investigated?
(ii) Is there any control in this experiment? If so, state the name.
(iii) Why was the plant kept in the dark before the experiment?
(iv) Describe step by step how the candidate proceeded to test the leaf for the presence of starch.
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उत्तर
(a) Carbon dioxide is returned back to the atmosphere mainly through the following ways:
(i) Respiration - Animals and plants respire and release carbon dioxide in the atmosphere.
(ii) Decay - Plants and animals decay organic matter with the help of bacteria and fungi and release carbon dioxide.
(iii) Combustion - Plants and animals which got buried under the soil changed into coal and oil and releases carbon dioxide when these are burnt.
(iv) Ocean water - Carbon dioxide occurs in the form of lime stone in molluscan shells and as by product of photosynthesis in marine water.
(b) (i) To show that sunlight is needed for photosynthesis.
(ii) Yes, the uncovered portion of the experimental leaf is the control.
(iii) To destarch the leaf.
(iv) 1. Boil the leaf in alcohol.
2. Wash the leaf in water to make it soft.
3. Add iodine solution on the leaf. The portion uncovered shows blue-black colour and the portion covered shows brown colour. This indicates that sunlight is needed for photosynthesis.
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संबंधित प्रश्न
The diagram below shows two test-tubes A and B. Test-tube A contains a green water plant. Test-tube B contains both a green water plant and a snail. Both testtubes are kept in sunlight. Answer the questions that follow:
(i) Name the physiological process that releases the bubbles of oxygen.
(ii) Explain the physiological process as mentioned above in Q2 (a)(i).
(iii) What is the purpose of keeping a snail in test-tube ‘B’?
(iv) Why does test-tube ‘B’ have more bubbles of oxygen?
(v) Given an example of a water plant that can be used in the above process.
(vi) Write the overall chemical equation for the above process.
Given below is an experiment setup to demonstrate a particualr tropic movement in germinating seeds. Study the diagram and answer the questions that follow :
(ii) Name the tropic movement shown by part 1.
Name the following:
The products that are formed as a result of photosynthesis.
Complete the following food chains by writing the names of appropriate organisms in the blanks:
______ → Mouse ______ → Peacock
Oxygen given out during photosynthesis comes from water. Explain this statement.
Explain, why respiration is said to be a reversed process of photosynthesis?
Name the molecules which are called assimilatory power? Why are they called so?
Fill in the blank by rearranging the letter in the bracket.
Pigment involved in the food synthesis is _________ (phllylochor).
Higher Order Thinking Skill.
Imagine that student A studied the importance of certain factors in photosynthesis. He took a potted plant and kept it in dark for 24 hours. In the early hours of the next morning, he covered one of the leaves with dark paper in the centre only. Then he placed the plant in sunlight for a few hours and tested the leaf which was covered with black paper for starch.
- What aspect of photosynthesis was being investigated?
- Why was the plant kept in the dark before the experiment?
- How will you prove that starch is present in the leaves?
- Name the raw materials needed for photosynthesis.
The source of O2 liberated in photosynthesis is ______.
