Final answer:
Biological membranes are described as fluid and selectively permeable, allowing them to control substance movement while their components move freely. The correct option is C.
Step-by-step explanation:
The structure of a biological membrane can be best described as fluid and selectively permeable. A biological membrane, such as the cell membrane, is composed of a phospholipid bilayer that allows for the fluidity of the membrane. The phospholipids have hydrophilic heads and hydrophobic tails, resulting in a self-assembling structure.
The fluid and selectively permeable nature of the membrane allows for the movement of molecules and ions through passive diffusion, facilitated diffusion, or active transport.The structure of a biological membrane is best described as fluid and selectively permeable. This means that while the components of the membrane move around freely, like a fluid, the membrane still controls what can enter or leave the cell, allowing only certain substances to pass through. The fluid nature is due to the phospholipid bilayer, which has a 'sea' of proteins that float around and perform various functions. Membranes are also made up of cholesterol, carbohydrates, and other lipids that contribute to its fluidity and selective permeability.