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Cell Physiology

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Role of Osmosis in Organisms

•Absorption of water from the soil-The root hair cell of plants absorbs water from the soil through osmosis. Osmosis also helps in distribution and movement of water from the roots to other parts of the plant.

•Osmosis plays an important role in support in herbaceous plants and young seedlings.When the cells of these plants take in water through osmosis, the cells become firm or rigid and thus gain support.

•Osmosis plays a role in opening and closing of stomata in plants- The guard cells surrounding the stomata synthesize glucose through photosynthesis in the presence of light.

As glucose accumulates in the guard cells, the osmotic pressure of the guard cells increase making them to draw water from adjacent cells through osmosis. When the guard cells become turgid, they bulge outwards leading to opening of the stomata.

Opening of the stomata is crucial as it allows for gaseous exchange in plants. At night,there is no glucose synthesis.

The glucose available in the guard cells is respired on leading to reduction of glucose and consequently reduction in osmotic pressure. The guard cells lose turgidity and close the stomata.

•Osmosis also plays a role in feeding in insectivorous plants- These plants live on nitrogen deficient soils and trap insects from whence they obtain the nutrients.

These plants possess special structures that suddenly change their turgor pressure when disturbed.

The change in turgor pressure enables the special structures to rapidly close thereby trapping the insects.

• Osmosis also plays a role in osmoregulation in animals.

•In kidney tubules of animals, water is withdrawn from the tubules into the body cells through osmosis through the tubular walls. This enables animals to maintain the osmotic pressure of the body fluids.

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