Final answer:
Membranes in cold environments contain higher proportions of unsaturated fatty acids to maintain fluidity, while membranes in hot environments have more saturated fatty acids to maintain stability.
Step-by-step explanation:
The fatty acid composition of cell membranes is crucial for maintaining the appropriate fluidity, which is particularly important for the function and survival of cells in different temperatures. In cold environments, the saturation levels of membrane fatty acids in plants and other organisms like fish are expected to be lower.
This is because membranes with a higher proportion of unsaturated fatty acids maintain fluidity even when temperatures drop. The kinks in unsaturated fatty acid tails create space between phospholipid molecules, preventing the membrane from becoming too dense and rigid.
In contrast, in hot environments, you would expect organisms to have a higher proportion of saturated fatty acids in their membranes. This is because saturated fatty acids with their straight tails pack more tightly together, which helps to stabilize the membrane structure in higher temperatures, where too much fluidity might be detrimental.
Therefore, the adaptation strategy involves varying the ratio of unsaturated to saturated fatty acids in the membrane to maintain the necessary membrane fluidity for proper cellular function in the given environment.