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प्रश्न
Explain the mechanism of closing and opening of the stomata.
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उत्तर
The closing and opening of the stomata depends on the turgidity of the guard cells. Each guard
cell has a thicker wall on the side facing the stoma and a thin wall on the opposite side. Guard cells contain chloroplasts. As a result of the synthesis of glucose during photosynthesis and some other chemical changes, the osmotic pressure of the contents of the guard cells increases and they absorb more water from the neighbouring cells, thus becoming turgid. Due to turgor, the guard cells become more arched outwards and the aperture between them widens, thereby opening the stoma.
At night or when there is shortage of water in the leaf, the guard cells turn flaccid and their inner rigid walls become straight, thus closing the stomatal aperture.
संबंधित प्रश्न
The process by which root hairs absorb water from the soil.
State whether the following statement is true or false. Rewrite the false statement correctly.
Water absorption mainly occurs through the root-hair.
Given below is the diagrammatic representation of the transverse section of a part of a plant. Study it and answer the questions that follow:
(a) Name the part of the plant that is shown
(b) Label the parts 1 to 6
(c) Write the functions of parts 3 and 5
Choose the correct answer:
An example of a selective permeable membrane is __________
The diagram below represents a layer of epidermal cells showing a fully grown root hair. Study the diagram and answer the questions that follow:
The root hair cell is in a turgid state. Name and explain the process that caused this state.
The figure given below is a diagrammatic representation of a part of the cross-section of the root in the root hair zone. Study the same and then answer the questions that follow :
(i) Name the parts indicated by guidelines ‘1’ to ‘5’
(ii) Is the root hair cell unicellular or multi-cellular?
(iii) Draw a labeled diagram of the root hair cell as it would appear if some fertilizer is added to the soil close to it.
(iv) Name the process responsible for the entry of water molecules from the soil into A1 and then A2.
(v) What pressure is responsible for the movement of water in the direction indicated by arrows?
(vi) How is this pressure set up?
Give Technical Term for the following.
Phenomenon of absorption of water by surface attraction.
Most plant cells and tissues constitutes _____ % water.
Draw a neat and labelled diagram of Root hair.
What is peculiarity of epiphytic plants like orchids?
