Question

The structure labeled ‘A’ is composed of

A. lipids.
B. carbohydrates.
C. proteins.
D. all of the above.


Which of the following is NOT true about the structure labeled 'D'?
A. It allows any molecule to pass.
B. It extends through the membrane.
C. It is a transport protein.
D. It moves substances across the cell membrane.

Answer 1

The structure labeled 'A' is composed of proteins. The structure labeled 'D' does not allow any molecule to pass through the membrane.

Step-by-step explanation:

The structure labeled 'A' in the question is composed of proteins. The cell membrane, or plasma membrane, is composed of a bilayer of phospholipids with proteins embedded in it. The proteins perform various functions, including transport of materials across the membrane.

The structure labeled 'D' in the second question that is NOT true about it is A. It allows any molecule to pass. The membrane is selectively permeable and only allows certain substances to pass through, while others are excluded based on their size, polarity, and charge.