Which of the following describes the tails of a phospholipid bilayer?

The tails of a phospholipid bilayer are characterized as hydrophobic and non-polar. This feature is crucial because it explains how phospholipids behave in an aqueous environment. The hydrophobic tails are composed of long fatty acid chains that do not interact favorably with water. Instead, they tend to associate with each other, minimizing their exposure to water and maintaining a stable structure.

In contrast, the hydrophilic heads of phospholipids are polar and interact well with water, creating a barrier that separates the contents of the cell from the external environment. This amphipathic nature of phospholipids—having both hydrophobic tails and hydrophilic heads—results in the formation of a bilayer, which is fundamental to cell membrane structure and function.

Understanding this property is essential for comprehending how cell membranes regulate the passage of substances in and out of cells, contributing to the overall homeostasis and functionality of the cell.