Membrane lipids in tissue samples obtained from different parts of a reindeer's leg have different fatty acid compositions. Membrane lipids from tissue near the hooves contain a larger proportion of unsaturated fatty acids than those from tissue in the upper leg. What is the significance of this observation?

At lower temperature, membranes maintain fluidity by having a higher percentage of unsaturated fatty acids.

Explanation:

The fluidity of the membranes is affected by temperature. At lower temperature conditions, tight packing of saturated fatty acids makes the membranes more rigid. Therefore, membranes incorporate a higher proportion of unsaturated fatty acids to maintain the required fluidity. This is why the membrane lipids from the tissue near the hooves have a higher proportion of unsaturated fatty acids as the temperature of the tissues of a reindeer near extremities is lower than that of the tissues from the upper leg.