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प्रश्न
Given below are the diagrams of a certain structure in plants in two conditions.
(i) Name the structure shown.
(ii) Name the parts numbered 1-5.
(iii) What is the most apparent difference between A and B in the structure shown?
(iv) Describe the mechanism which brings about the change in the structure depicted in A and B.
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उत्तर
(i) Stomata surrounded by epidermal cells.
(ii)
- Chloroplast,
- The inner wall of guard cells,
- Nucleus,
- Guard cells,
- Stoma.
(iii) The stoma is open in A and is almost closed in B.
(iv) The opening and dosing mechanism of stomata is regulated by the amount of water and solutes present in the guard cells. The guard cells have a thick inner wall facing the opening and a thin outer wall on the opposite side; their cytoplasm contains chloroplasts. During the day guard cells begin photosynthesis and the sugar produced during the process increases the osmotic pressure which draws in water from the adjoining cells. Hence, the guard cells become turgid and bulge outward due to their thin outer wall, thus widening the stomatal opening lying in between (A). As the stomata open, the diffusion of gases in and out begins to fulfilling the need for photosynthesis and for allowing transpiration. If for any reason the water content of the leaf is falling short, the guard cells fail to remain turgid, they turn flaccid or lose turgidity, thereby closing the stomatal opening (B) and the transpiration stops.
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संबंधित प्रश्न
How do stomata differ from a lenticel?
Differentiate Between Cobalt chloride paper and Goat’s bladder.
Given below is the diagram of an experimental set up to study the process of transpiration in plants. Study the same and then answer the questions that follow:
(i) What is the colour of dry cobalt chloride paper?
(ii) Is the experimental leaf a monocot or a dicot? Give a reason to support your answer.
(iii) Why axe glass slides placed over the dry cobalt chloride papers?
(iv) After about half an hour what change, if any, would you expect to find in the cobalt chloride paper placed on the dorsal and ventral sides of the leaf? Give a reason to support your answer.
(v) Define the term ‘transpiration’.
Given below is an apparatus used to study a particular process in plants. Study the same and answer the questions that follow :
(i) Name the apparatus.
(ii) Mention one limitation of this apparatus.
(iii) Which phenomenon is studied with the help of this apparatus?
(iv) What is the function of the part marked ‘reservoir’?
(v) What is the role of the air bubble in the experiment?
Assertion (A): The loss of excess water from the aerial parts of the plant in the form of water vapor is known as transpiration.
Reason (R): Stomata of the leaf perform transpiration.
Name the following:
The openings on the barks of trees through which transpiration occurs.
The upper layer of mesophyll in a leaf consists of elongated ground tissue called ______.
The given figure represents an experiment:
- Leaf A was coated with grease on both surfaces.
- Leaf B was coated with grease on the lower surface.
- Leaf C was coated with grease on the upper surface.
- Leaf D was left without any application of grease. All four leaves A, B, C and D were left in a room for about 24 hours.
- Which leaf dries first? Give reason.
- Which leaf dries last? Give reason.
