Advertisements
Advertisements
प्रश्न
Explain the mechanism of closing and opening of the stomata.
Advertisements
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
Which one of the following is a characteristic NOT related with the suitability of the roots for absorbing water?
Concentration of mineral nutrient elements is higher inside the root hairs than in the surrounding soil. How do roots take them in from the soil?
The diagram given below represents a plant cell after being placed in a strong sugar solution. Guidelines 1 to 5 indicate the following:
1. Strong sugar solution
2. Cell wall
3. Protoplasm
4. Large vacuole
5. Nucleus
Study the diagram and answer the questions that follow:
(i) What is the state of the cell shown in the diagram?
(ii) Name the structure which acts as a selectively permeable membrane.
(iii) If the cell had been placed in distilled water instead of strong sugar solution which feature would not have been present?
(iv) If the cell in the diagram possessed chloroplasts where would these be present?
(v) Name any one feature of this plant cell which is not present in animal cells.
Name the following:
The kind of cells that constitute the cortex of a root.
Give Technical Term for the following.
Tissue which transports manufactured food from leaves to other parts of the plant.
Give Technical Term for the following.
The tissue responsible for the ascent of sap in plants.
Water which is absorbed by roots is transported to aerial parts of the plant through ______
Minerals cannot be passively absorbed by the roots.
____________plants like orchids absorb water vapours from air with the help of epiphytic roots having special tissue called velamen.
What is peculiarity of epiphytic plants like orchids?
