Question

1. which phrase best describes the structure of a cell membrane? a. porous protein sheet b. water - filled, rigid tubules c. an impenetrable carbohydrate matrix d. flexible, semipermeable bilayer of phospholipids

Explanation:

The cell - membrane is composed of a phospholipid bilayer. It is flexible and semi - permeable, allowing certain substances to pass through while restricting others. It is not a porous protein sheet, water - filled rigid tubules, or an impenetrable carbohydrate matrix.

Answer:

d. flexible, semipermeable bilayer of phospholipids