Question

Question: Which of the following factors would tend to increase membrane fluidity?

1. a greater proportion of unsaturated phospholipids
2. a greater proportion of saturated phospholipids
3. a lower temperature
4. a relatively high protein content in the membrane

Short answer

1. The statement “a greater proportion of unsaturated phospholipids.” is true.
2. The statement “a greater proportion of saturated phospholipids” is false.
3. The statement “a lower temperature” is false.
4. The statement “a relatively high protein content in the membrane” is false.

Step-by-step solution

Cell membrane

A layer of biological components that surrounds a cell is known as a cell membrane. It needs to have fluid ability to facilitate the transportation of materials across the membrane. Cholesterol is the substance that is responsible for this property.

Explanation of option ‘(A)’ 

Unsaturated phospholipids are lipids that have the presence of one double bond. This presence of double bond is an important property to increase membrane fluidity.

Thus, greater amount of unsaturated phospholipids can increase membrane fluidity.

Therefore, the given statement is true.

Explanation of option ‘(B)’

Saturated phospholipids contain lipids that lack the presence of a double bond. Without a double bond, the saturated phospholipid does alter the membrane fluidity.

Thus, the proportion of saturated fatty acids does not change the fluidity of the membrane.

Therefore, the given statement is false.

Explanation of option ‘(C)’

The membrane fluidity is dependent on the temperature. The increase in temperature can improve the fluidity of the membrane.

The lower temperature does not increase the membrane fluidity. Instead, it decreases membrane fluidity.

Therefore, the given statement is false.

Explanation of option ‘(D)’

Protein is the biological component present in the cell membrane. The fluidity is the property entirely dependent on the length of the fatty acid chain, temperature, and saturation level.

Thus, membrane fluidity is not a property that is determined by the protein.

Therefore, the given statement is false.