Which class of lipids is primarily found in cell membranes?

• A. Waxes
• B. Phospholipids
• C. Steroids
• D. Triglycerides

Answer: (B)

Verified step by step guidance

1. Understand the structure and function of cell membranes: Cell membranes are primarily composed of a bilayer that acts as a barrier and regulates the movement of substances in and out of the cell.
2. Identify the key lipid class involved in forming the bilayer: Phospholipids are amphipathic molecules, meaning they have both hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails, which are essential for forming the bilayer structure.
3. Compare the other lipid classes: Waxes are primarily used for waterproofing and protection, steroids are involved in signaling and structural roles (e.g., cholesterol), and triglycerides are used for energy storage. None of these are primarily involved in forming cell membranes.
4. Recognize the unique role of phospholipids: The hydrophilic heads face outward toward the aqueous environment, while the hydrophobic tails face inward, creating the selective permeability of the membrane.
5. Conclude that phospholipids are the primary lipid class found in cell membranes due to their structural and functional properties.