Certain prokaryotes and eukaryotes adapt to changing environments by changing the unsaturated hydrocarbon tails of the plasma membrane.
a. true
b. false

True

Explanation:

Many organisms like bacteria and animals can adapt to cold environments by changing the proportion of unsaturated fatty acids, avoiding freeze the plasma membrane.

The plasma membrane has the function to protect the cells from their surroundings. It is composed of a phospholipid bilayer with embedded carbohydrates, proteins and in animals’ cells cholesterol, giving a fluid characteristic. This fluidity is given for the characteristics of the phospholipids. Saturated fatty acids have one bond between atoms making a rigid structure in cold temperatures, making saturated fatty acids solidify and the membrane gest rigid and is susceptible to rupture. Phospholipids with unsaturated fatty acids have double bonds between atoms, making the membrane more flexible and in cold temperatures, the unsaturated fatty acids don´t freeze, maintaining the fluidity of the membrane.