Question

which of the following statements regarding selective permeability of the plasma membrane defines its full meaning? select an answer a. a process that allows some substances to cross with or without help from transport proteins, while other substances are excluded from crossing altogether b. a process that allows all substances to cross with or without help from transport proteins c. a process that only allows substances to cross with help from transport proteins d. a process that requires energy input and active transport to allow substances to cross

Explanation:

Selective permeability of the plasma membrane means that it allows certain substances to pass through, either with or without the aid of transport proteins, while preventing other substances from crossing. This is a fundamental property of the plasma - membrane that helps maintain cellular homeostasis. Option B is incorrect as not all substances can cross. Option C is wrong because some substances can cross without transport proteins (e.g., small non - polar molecules by simple diffusion). Option D is inaccurate as not all selective permeability requires energy input (passive transport processes like simple and facilitated diffusion don't require energy).

Answer:

A. a process that allows some substances to cross with or without help from transport proteins, while other substances are excluded from crossing altogether