What happens to the phospholipid bilayer as temperature increases?

As temperature increases, the phospholipid bilayer becomes more fluid. This occurs because the increased kinetic energy causes the phospholipid molecules to move more rapidly, resulting in greater space between the molecules. The fluidity of the bilayer is essential for various cellular functions, such as the movement of proteins within the membrane and the ability of the cell to transport substances in and out through vesicular transport. A more fluid bilayer allows for easier adjustments to the membrane's composition and an improved capacity for cellular signaling.

In contrast, a compact bilayer would limit mobility and flexibility, which is not supportive of the dynamic nature of cell membranes. Therefore, as the temperature rises, the ability of lipids to move about increases, making the bilayer more fluid and enhancing its functional capabilities.