Osmosis – Class 11 | Chapter – 11 | Biology Short Notes Series PDF

Osmosis: It is the spontaneous gross diffusion or movement of solvent molecules via a selectively permeable membrane from an area of high water potential to a region of lower water potential in the direction which has a tendency for equalizing concentrations of solute on both sides. It can be described as a physical phenomena wherein any solvent moves through a selectively permeable membrane which separates two solutions of varying concentrations.

Features of Osmosis

  • It is a process by which plants maintain their water content despite the constant water loss due to transpiration.
  • This process controls the cell to cell diffusion of water.
  • It induces cell turgor which regulates the movement of plants and plant parts.
  • It also controls the dehiscence of fruits and sporangia.
  • Higher osmotic pressure protects the plants against drought injury.
  • It influences the transport of nutrients and the release of metabolic waste products.
  • It is responsible for the absorption of water from the soil and conducting it to the upper parts of the plant through the xylem.
  • It stabilizes the internal environment of a living organism by maintaining the balance between water and intercellular fluid levels.
  • It maintains the turgidity of cells.

Types of Osmosis

  • Endosmosis: When a substance is placed in a hypotonic solution, water moves inside the cell making it swell or plasmolyze.
  • Exosmosis: When a substance is placed in a hypertonic solution, the water inside the cell moves outside, and thus the cell plasmolysis (becomes flaccid).

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By Team Learning Mantras