Describe (or draw) an example of diffusion down a concentration gradient.

Verified step by step guidance

1. Step 1: Understand the concept of diffusion as the passive movement of molecules from an area of higher concentration to an area of lower concentration, driven by the concentration gradient.
2. Step 2: Consider a simple example such as oxygen molecules moving from the air inside the lungs (where oxygen concentration is high) into the blood (where oxygen concentration is lower).
3. Step 3: Visualize or describe the process where oxygen molecules naturally spread out, moving across the thin membrane of the alveoli into the bloodstream without the need for energy input.
4. Step 4: Note that this movement continues until equilibrium is reached, meaning the concentration of oxygen is equal on both sides of the membrane.
5. Step 5: Emphasize that diffusion is crucial in many biological processes, such as gas exchange in respiration and nutrient absorption in cells.

Key Concepts

Diffusion

Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, driven by the concentration gradient. It does not require energy and continues until equilibrium is reached.

Concentration Gradient

A concentration gradient exists when there is a difference in the concentration of a substance between two regions. Molecules naturally move down this gradient, from high to low concentration, to balance the distribution.

Examples of Diffusion in Biological Systems

Common examples include oxygen moving from the lungs into the blood and carbon dioxide moving out, or nutrients diffusing into cells. These illustrate how diffusion facilitates essential exchanges in living organisms.