Paper 3 · November 2023 · Cell Structure and Membranes
At high temperature, cholesterol in a cell surface membrane
Acauses the phospholipid tails to pack more closely together, solidifying the membrane.
Brestricts the movement of phospholipids, reducing membrane fluidity.
Cincreases the membrane's permeability to glucose directly.
Dbreaks down to release extra energy for active transport.
Explanation
At high temperature phospholipids would otherwise move too freely; cholesterol interposed between them restricts this movement and stops the membrane becoming excessively fluid or leaky.
Derived from ZIMSEC Biology 6030/3 Paper 3, November 2023, Q1