Question

multiple choice question
increased gas diffusion across the rbc membrane and their ability to pass through small blood vessels can be attributed to

their biconcave shape
increased cholesterol in the plasma membrane
the precipitation of hemoglobin along the plasma membrane
the flexible nuclear membrane

Explanation:

Red - blood cells (RBCs) have a biconcave shape. This shape increases the surface - area to volume ratio, facilitating gas diffusion across the RBC membrane. Also, the biconcave shape allows RBCs to deform and pass through small blood vessels. Cholesterol in the plasma membrane affects membrane fluidity but not gas diffusion and vessel - passing ability in the way described. Hemoglobin is not precipitated along the plasma membrane, and RBCs in mammals lack a nucleus and thus a nuclear membrane.

Answer:

their biconcave shape