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प्रश्न
Will the ascent of sap be possible without the cohesion and adhesion of the water molecules? Explain.
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उत्तर
In plants, the ascent of sap involves factors like root pressure, capillary action, adhesion-cohesion and transpiration. The movement of water up to the base of the stem is resulted only by root pressure. Water can raise only a few centimetres by capillary action so it is effective only in herbs. When there is a water column underneath which is to be pulled only then transpiration pull works. Hence, without adhesion-cohesion of water molecules ascent of sap is not possible.
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संबंधित प्रश्न
What are stomata?
Briefly explain, how transpiration helps in upward conduction of water in plants?
How does transpiration help the roots absorb water and minerals from the soil?
(a) State whether the following statement are True or False.
(b) Rewrite the false statement in the correct form by changing either the first or the last word only.
Most transpiration occurs at midnight.
Give suitable explanation for the following:
Cork and bark of trees help in preventing loss of water
Given alongside is the diagram of an experimental set-up to demonstrate a certain phenomenon in plants.
Name the phenomenon being demonstrated.
The diagram given alongside is an apparatus used to study a particular phenomenon in plants.
(i) Name the apparatus.
(ii) What is it used for?
(iii) What is the role played by the air bubble in this experiment?
(iv) Of what use is the reservoir?
Give a reason.
What happens to the movement of the air-bubble if the apparatus shown above is kept in dark.
Litmus paper is used to demonstrate transpiration from the leaves of the green plant.
A well watered healthy potted plant with variegated leaves was kept in darkness for about 24 hours. It was then set up as shown in the diagram and exposed to light for about 12 hours. At the end of this time, leaf x and y were tested for starch. Study the diagram and answer the questions that follow:
(i) Why was the plant initially kept in darkness for 24 hours?
(ii) What is the function of sodium hydroxide solution in the flask?
(iii) Select the correct leaf from the five available choices shown in the diagram as a, b, c, d and e. Rewrite the correct answer by filling in the appropriate letter for the questions that follow:
1. After the starch test, leaf x would look like ______.
2. After the starch test, leaf y would look like ______.
(iv) The experiment with leaf y shows that photosynthesis requires the presence of certain factors. Mention any one factor.
The figure given below represents an experimental setup with a weighing machine to demonstrate a particular process in plants. The experimental setup was placed in bright sunlight. Study the diagram and answer the following questions.
Name the process intended for study.
An apparatus as shown below was set up to investigate a physiological process in plants. The setup was kept in sunlight for two hours. Droplets of water were then seen inside the bell jar. Answer the questions that follow:
Mention two ways in which this process is beneficial to plants.
What causes the opening and closing of guard cells of stomata during transpiration?
Transpiration is a necessary evil in plants. Explain.
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A root hair is derived from ______ cell.
