Answer
D. Polar bear
Work Step by Step
Polar bears live in very cold environments, where their cell membranes may become too rigid if they have too many unsaturated phospholipids. As a result, polar bears are more likely to have a higher proportion of saturated phospholipids in their cell membranes to maintain their structure and function at low temperatures. because they are sea mammals, polar bears eat a lot of fatty foods, especially fish. Omega-3 fatty acids, which are known to be abundant in fish and can integrate into cell membranes, are unsaturated fatty acids. Yet, polar bears have evolved to store a lot of fat in their bodies to withstand extended fasting periods, and the fat they do so contains a lot of saturated fatty acids. Hence, it is more likely than not that polar bears' cell membranes have a higher proportion of saturated phospholipids than unsaturated phospholipids.
