Q1. Answer the following questions:
- (a)) What are the various constituents of cell membrane? Describe the modes by which cell membrane controls the transport of ingoing and outgoing molecules. (200 words)
- (b)) Describe the classification of carbohydrates giving examples for each class. (200 words)
Key Points:
- Cell membrane comprises phospholipids, proteins, cholesterol, and carbohydrates forming a fluid mosaic model.
- Passive transport moves molecules down gradient without energy via diffusion, facilitated diffusion, or osmosis.
- Active transport uses ATP to move molecules against gradient (e.g., Na⁺/K⁺ pump) or electrochemical gradients.
- Carbohydrates are classified as monosaccharides, oligosaccharides, and polysaccharides based on unit count.
Answer: The cell membrane is a dynamic, selectively permeable barrier composed mainly of a phospholipid bilayer, integral and peripheral proteins, cholesterol, and carbohydrates. Phospholipids form the foundational double layer, defining the cell's boundaries due to their amphipathic nature. Proteins embedded within or associated with the membrane perform critical functions, including acting as channels, carriers, receptors, and enzymes. Cholesterol, found in animal cell membranes, modulates fluidity a...