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 refers to the movement of water molecules across a selectively permeable membrane. This process is vital for maintaining homeostasis within cells and organisms. In osmosis, water moves from an area where it is in higher concentration (more water molecules, fewer solute particles) to an area where it is in lower concentration (fewer water molecules, more solute particles). This movement occurs to balance the concentration of solutes on both sides of the membrane.
The selectively permeable membrane allows water molecules to pass through while restricting the movement of solutes. This differential permeability is essential because it helps cells regulate their internal environment. For example, when a cell is placed in a hypertonic solution (higher solute concentration outside the cell), water will move out of the cell, causing it to shrink. Conversely, in a hypotonic solution (lower solute concentration outside), water will enter the cell, potentially leading to swelling and even bursting if too much water enters.
Osmosis is driven by the principle of diffusion, where substances tend to move from regions of high concentration to low concentration until equilibrium is reached. This process does not require energy (ATP) because it relies on the natural kinetic energy of water molecules. Understanding osmosis is crucial in fields such as biology and medicine, as it affects processes like nutrient absorption, waste removal, and overall cellular function. For example, in medical treatments like IV fluid administration, the osmotic balance is critical to ensure proper hydration and nutrient delivery to cells.