Which of the following describes the process of osmosis?
A.
Movement of substances from an area of high concentration to an area of low concentration.
B.
Movement of substances against a concentration gradient with the help of transport proteins.
C.
Movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane.
D.
Movement of substances into a cell by engulfing them with the plasma membrane.
The correct answer and Explanation is :
The correct answer is C: Movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane.
Explanation:
Osmosis is a specific type of passive transport that involves the movement of water across a selectively permeable membrane. This process is fundamental to maintaining cellular function and homeostasis.
- Selectively Permeable Membrane: The selectively permeable membrane refers to a barrier that allows certain substances to pass through while blocking others. In the context of osmosis, the membrane is usually permeable to water but not to solutes (e.g., salts, sugars).
- High to Low Concentration: Osmosis involves water molecules moving from a region where they are in higher concentration (i.e., where there is less solute) to a region where they are in lower concentration (i.e., where there is more solute). This movement aims to equalize the solute concentration on either side of the membrane.
- Passive Transport: Unlike active transport processes that require energy input, osmosis does not require energy. It relies on the natural tendency of water molecules to move toward areas of higher solute concentration, which balances the concentration gradients.
- Importance: Osmosis is crucial for various physiological processes, such as regulating blood pressure, maintaining cell turgor in plants, and ensuring proper fluid balance in the body. For example, in animal cells, osmotic balance helps prevent cells from becoming too swollen or shriveled.
In summary, osmosis is the diffusion of water through a selectively permeable membrane from an area of high water concentration (or low solute concentration) to an area of low water concentration (or high solute concentration), aiming to achieve equilibrium. This process is vital for maintaining the appropriate hydration and solute balance within cells and across tissues.