[5 Mark Question Answer]

Question 15 Marks

The diagram alongside represents a structure found in a leaf. Study the same and answer the questions that follow:
(i) Name the parts labeled A and B.
(ii) What is the biological term for the above structure?
(iii) What is the function of the part labeled A?
(iv) Mention two structural features of A, which help in the function mentioned in (iii) above?
(v) Where is this structure likely to be found in a leaf?
(vi) The structure (fig.5.22) helps in the process of transpiration. Explain the term transpiration.
(vii) How many other cells are found surrounding this structure as seen in the diagram?

Answer

(i) A = Guard cell
B = Stomatal aperture
(ii) Stomata
(iii) The function of the guard cells are that they help to regulate the rate of transpiration by opening and closing the stomata thus preventing excessive water loss.
(iv) The two structural features of guard cells are :
1.The guard cells have thin outer wall and thick inner wall.
2. Guard cells contain chloroplast in their cytoplasm.
(v) These are present on the lower surface of the dorsiventral leaf.
(vi) Transpiration is the loss of water in the form of water vapour from aerial parts of the plant.
(vii) Five

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Question 25 Marks

Describe an experiment to prove that transpiration occurs more from the lower surface of a leaf.

Answer

An experiment to prove that transpiration occurs more from the lower surface of a leaf :

Take a potted plant.
Place two Cobalt chloride papers on either side of a leaf of the potted plant with the help of two glass slides .
Keep the plant in sunlight.
After sometime it is observed that the cobalt chloride paper on the lower side of the leaf changed its colour to pinkish than the upper side . This shows that rate of transpiration is more on the lower surface of a leaf .

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Question 35 Marks

Differentiate between guttation and bleeding in plants.

Answer

Guttation	Bleeding
It is the removal of excess water from the plants because of excess water buildup in the plant.	It is the removal of water from the plant because of injury.
Water escapes from specialised structures called hydathodes.	Water escapes in the form of sap from the injured part of the plant.
It occurs from edges of leaves.	It occurs from cuts found in plants.
It happens due to the pressure presents in the xylem.	It happens due to pressure in sieve tubes.

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Biology [5 Mark Question Answer]

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