Give reasons for the following:
(a) If you sprinkle some common salt on grass growing on a lawn,it is killed at that spot.
(b) If you uproot a plant from the soil,its leaves soon wilt.
(c) It is better to transplant seedlings in a flower-bed in the evening and not in the morning.
(d) A plant cell when kept in a hypertonic salt solution for about 30 minutes turns flaccid.
(e) Potato cubes when placed in water become firm and increase in size.
Give reasons for the following:
(a) If you sprinkle some common salt on grass growing on a lawn,it is killed at that spot.
(b) If you uproot a plant from the soil,its leaves soon wilt.
(c) It is better to transplant seedlings in a flower-bed in the evening and not in the morning.
(d) A plant cell when kept in a hypertonic salt solution for about 30 minutes turns flaccid.
(e) Potato cubes when placed in water become firm and increase in size.
(a) Common salt, when sprinkled on the grass, causes the Plasmolysis of grass cell ultimately leading them to death. Hence, if we sprinkle some common salt on grass growing on a lawn, it is killed at the spot.
(b) If a plant is uprooted, the leaves continue losing water by transpiration, but there is no more water absorbed the roots. This does not allow the compensation for the loss of water by transpiration; hence the leaves of the uprooted plant wilt soon.
(c) Transplantation causes stress to the seedlings. If the seedlings are transplanted in the morning, they would have to immediately bear the additional stress of excessive transpiration occurring during the hot afternoon. Transplantation in the evening helps the seedlings to adjust for a longer time during the night (cooler temperatures) because the quantity of water absorbed exceeds the loss of water through transpiration. Therefore, it is better to transplant seedling in a flower bed in the evening and not in the morning.
(d) In a hypertonic solution, the solution outside the cell has a higher solute concentration than the fluids inside the cell. Therefore, water flows out from the plant cell due to exosmosis. The cytoplasm shrinks and the plasma membrane withdraws away from the cell wall and this the cell becomes flaccid. Hence a plant cell when kept in a hypertonic salt solution for about 30 minutes turns flaccid.
Potato cubes contain an excess of salts and sugars as compared to the water in which the cubes are placed. Hence, due to endosmosis, water from the surrounding enters the potato cubes making them firm and increasing their size.
(a) Common salt, when sprinkled on the grass, causes the Plasmolysis of grass cell ultimately leading them to death. Hence, if we sprinkle some common salt on grass growing on a lawn, it is killed at the spot.
(b) If a plant is uprooted, the leaves continue losing water by transpiration, but there is no more water absorbed the roots. This does not allow the compensation for the loss of water by transpiration; hence the leaves of the uprooted plant wilt soon.
(c) Transplantation causes stress to the seedlings. If the seedlings are transplanted in the morning, they would have to immediately bear the additional stress of excessive transpiration occurring during the hot afternoon. Transplantation in the evening helps the seedlings to adjust for a longer time during the night (cooler temperatures) because the quantity of water absorbed exceeds the loss of water through transpiration. Therefore, it is better to transplant seedling in a flower bed in the evening and not in the morning.
(d) In a hypertonic solution, the solution outside the cell has a higher solute concentration than the fluids inside the cell. Therefore, water flows out from the plant cell due to exosmosis. The cytoplasm shrinks and the plasma membrane withdraws away from the cell wall and this the cell becomes flaccid. Hence a plant cell when kept in a hypertonic salt solution for about 30 minutes turns flaccid.
Potato cubes contain an excess of salts and sugars as compared to the water in which the cubes are placed. Hence, due to endosmosis, water from the surrounding enters the potato cubes making them firm and increasing their size.
