Colloids are primarily composed of which substances?

• A. Dissolved salts
• B. Proteins
• C. Carbohydrates
• D. Water

Answer: (B)

Colloids are mixtures where the dispersed particles are relatively large and stay suspended in the surrounding fluid. In many biological contexts, the dispersed phase that creates colloids is made up mainly of proteins—things like albumin, globulins, and fibrinogen. Water is simply the solvent, and dissolved salts form true solutions rather than colloidal particles. Carbohydrates can be part of larger molecules but aren’t the primary colloidal material in this setting. So, the best answer is proteins, since they are the primary components that give colloids their characteristic suspended particles and functional role in things like maintaining vascular oncotic pressure.