AP BIOLOGY

Detailed explanation-1: -The most widely accepted model for plasma membrane structure is the fluid-mosaic model . According to this model, the plasma membrane is made up of a phospholipid bilayer which has proteins embedded in it. These proteins can be extrinsic or external proteins or intrinsic or internal proteins.

Detailed explanation-2: -The correct answer is (C) A flexible lipid double layer. The cell membrane is often referred to as a “fluid mosaic, ” a flexible structure containing phospholipids as well as some proteins and other important molecules.

Detailed explanation-3: -So, the correct answer is ‘Two layers of phospholipids where the outer layer has the hydrophilic heads facing toward the outside of the cell and the inner layer have the hydrophobic tails facing toward the inside of the cell.

Detailed explanation-4: -The phospholipid bilayer is made of two layers of phospholipids. Each phospholipid has a hydrophilic head and a hydrophobic tail. The two layers are arranged so that the tails face inward and the hydrophilic heads face outward toward the extracellular environment or the intracellular cytoplasm.

Detailed explanation-5: -The phospholipids withinside the plasma membrane are organized in layers, referred to as a phospholipid bilayer, with a hydrophobic, or water-hating, indoors and a hydrophilic, or water-loving, exterior . So, the answer is option d) It is a bilayer of phospholipids with associated proteins and carbohydrates.