The plasma membrane of a cell and the membrane boundaries of organelles,such as mitochondria and chloroplasts,serve similar functions.What is one of the main functions of the membranes of both cells and organelles?
A) They keep reactants near each other to speed biological reactions.
B) They allow external chemicals to diffuse freely into and out of the cell.
C) They encourage cellular respiration at the membrane boundaries.
D) They keep water out of the cell and organelle interiors.

Question

Quizplus · Accepted Answer

Both cell and organelle membranes compartmentalize the cell and organelles, keeping reactants near each other to speed up biological reactions. This is essential for efficient cellular and metabolic processes. Option B is incorrect because membranes control the movement of molecules in and out of the cell or organelle, not allowing them to freely diffuse. Option C is incorrect because while mitochondrial membranes are important for cellular respiration, chloroplast membranes are important for photosynthesis rather than respiration. Option D is incorrect because membranes are selectively permeable, allowing water and other necessary molecules to pass through them.

The Plasma Membrane of a Cell and the Membrane Boundaries