All of the following about the cell membranes are true except: a. membrane fluidity decreases with increasing cholesterol content b. cell membrane’s property remains constant and univariable c. membrane’s fluidity depends on the length and saturation of its phospholipids’ fatty acid tails d. cell membrane’s property varies depending the on types and proportions of molecules composing it

The viscosity of a cell membrane's lipid bilayer, commonly known as membrane fluidity, can impact the rotation and diffusion of proteins and other biomolecules inside the membrane, influencing their activities.

Because the cell membrane is made up of a variety of molecules that are dispersed across the membrane, scientists use the fluid mosaic model of the cell membrane to describe how it appears and operates.

These properties do not remain constant and invariable and can be affected by a big number of factors, such as:

Lenght and saturation of the fatty acids that compose the phospholipids present in the membrane: the shorter the chains, the less viscous the membrane. Because double carbon bonds (unsaturated) cannot readily spin, lipid chains containing these are stiffer than lipid chains saturated with hydrogens.
Melting temperature: heating the membrane is one technique to improve its fluidity. When lipids are heated, they gain thermal energy; energetic lipids move about more, randomly organizing and rearranging, making the membrane more fluid.
Cholesterol: the cholesterol keeps the phospholipids together so they don't split too much, allowing undesirable things in, or compress too tightly, limiting mobility across the membrane.

In conclusion, there are several factors involved in the fluidity of the lipid bilayer that do depend on the types, proportions and properties of the molecules composing it.

To learn more about the fluid mosaic model, read here: https://brainly.com/question/14931617