The term used for diffusion of solvent through a semipermeable membrane is known as: (a) Osmosis (b) Plasmolysis (c) Diffusion (d) Active absorption

A semipermeable membrane, sometimes called a selectively permeable or partially permeable membrane, acts like a gatekeeper in biological systems. It allows certain substances, typically small molecules like water, to pass through while blocking others, such as larger molecules or ions. This biological feature is critical in the process of osmosis.

Imagine a fine sieve that can separate finer grains from coarser ones; similarly, a semipermeable membrane can distinguish between particles based on size, charge, or other properties. Cell membranes are classic examples of semipermeable membranes—they allow nutrients into the cell while keeping out toxins.

Importance in Living Organisms

These membranes are essential for maintaining homeostasis in cells. Without this selective permeability, cells couldn't regulate their internal environments, leading to potential harm or dysfunction.

Imagine you're adding a spoon of sugar to your tea and watching it dissolve. This process of one substance spreading out to uniformly occupy a space is known as diffusion. Solvent diffusion specifically refers to the movement of the solvent molecules, like water, across a semipermeable membrane.

When it comes to osmosis, this movement is driven by the desire to reach equilibrium—the solvent naturally moves from an area where it is more concentrated to where it is less so. In biological contexts, this usually means water molecules moving in and out of cells to balance concentration across the membrane.

Role in Homeostasis

Through solvent diffusion, organisms can regulate water content within their cells and tissues, which is vital for processes like nutrient absorption and waste removal.

The concentration gradient refers to the difference in the concentration of a substance between two regions. Molecules will move from an area of higher concentration to one of lower concentration until the concentration becomes equal in both areas—this is driven by the random motion of particles and is a form of passive transport.

In the context of osmosis, a concentration gradient would exist across a semipermeable membrane whenever there is a difference in solute concentration between the inside and outside of a cell. The solvent (often water) moves to balance these concentrations, which naturally aligns with the flow from high to low water concentration, thus reducing the gradient.

Effects on Cellular Function

A strong concentration gradient can lead to rapid water movement into or out of cells, which can cause cells to swell and possibly burst, or to shrivel and die—both scenarios that can disrupt biological functions.