Question

multiple choice question which of the following is a defining feature of biological membranes? the presence of two phospholipid sheets the presence of a single phospholipid sheet the presence of one phospholipid sheet and one protein sheet the presence of two protein sheets

Explanation:

Biological membranes (like cell membranes) are mainly composed of a phospholipid bilayer, which means two phospholipid sheets (layers) with their hydrophobic tails facing inward and hydrophilic heads facing outward. The other options are incorrect: a single phospholipid sheet is not the structure, and protein sheets are not the defining lipid - based structural feature of biological membranes.

Answer:

A. The presence of two phospholipid sheets