The following diagram shows the different part of a plant. A gas 'B' is required as one of the raw materials in this chemical process. Name it.

Photosynthesis is the process by which green plants, in the presence of chlorophyll and light energy, manufacture carbohydrates from carbon dioxide and water. Here B represents carbon dioxide gas used by the plants during the process of photosynthesis. During the process of photosynthesis, oxygen gas is released. The oxygen is utilised by the living organisms for their survival.

The following diagram shows the different parts of a plant. How would you test the presence of carbon dioxide?

The experiment to show the presence of carbon dioxide during photosynthesis: Materials required: A wide-mouth glass bottle, a potted plant, potassium hydroxide solution, alcohol, water, a bunsen burner, a rubber cork, wire gauze, tripod stand, a beaker, a dropper and iodine solution. Procedure: Take a potted plant having long and narrow leaves and place it in a completely dark room for 2-3 days in order to destarch the leaves. Take a glass bottle having a wide-mouth and put some potassium hydroxide solution in it. Potassium hydroxide solution absorbs the carbon dioxide gas present in the glass bottle. Take a rubber cork that fits tightly to the mouth of the glass bottle and cut it into two halves. Insert one destarched leaf which is still attached to the plant into this glass bottle through the split cork. The upper half of the leaf should remain outside the glass bottle whereas the lower half of the leaf should be inserted in the glass bottle. Keep the potted plant in the sunlight for 3 to 4 days. Pluck the leaf from the plant and take it out from the glass bottle. A decolourised leaf is obtained by removing the chlorophyll from the leaf by boiling it first in water and then in alcohol. Wash the leaf again with water. Add a few drops of iodine over the colourless leaf and observe carefully. Observation: The upper half of the leaf (which was outside the glass bottle) turns blue-black on adding iodine solution whereas the lower half of the leaf (which was inside the glass bottle) does not turn blue-black. Discussion: As starch is not formed in the lower half of the leaf, it does not turn blue-black. The lower half of the leaf was inside the glass bottle where there was no carbon dioxide. As starch is formed on the upper half of the leaf, it turns into blue-black. Therefore, photosynthesis occurred here. Conclusion: This shows that carbon dioxide is necessary for photosynthesis.

The following diagram shows the different parts of a plant. Name the other raw material C, which is essential for the process.

Photosynthesis is a process through which plant can prepare their own food with the help of raw materials like water, carbon dioxide, sunlight. Plants absorb water through their roots and pass to the leaf through the stem.

E M B I B E

WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 11 - Nutrition in Plants>EVALUATE>Q 5

MEDIUM

7th CBSE

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Which organ in the human body has a similar function as that of the stomata in plants?

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Important Questions on Nutrition in Plants

MEDIUM

7th CBSE

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WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 11 - Nutrition in Plants>EVALUATE>Q 1

Explain why can't animals make their own food by using carbon dioxide, water, soil and sunlight. If they can't make their food how do they get the energy to survive?