Questions: How are the phospholipids arranged to form the plasma membrane? Multiple Choice Single layer with hydrophilic heads outward Double layer with hydrophobic tails facing inward toward each other Double layer with hydrophilic heads facing inward toward each other Double layer with phospholipids on the outside and proteins on the

The answer is the second one: Double layer with hydrophobic tails facing inward toward each other.

Explanation for each option:

1. Single layer with hydrophilic heads outward: This is incorrect. The plasma membrane is not a single layer but a bilayer (double layer) structure.

2. Double layer with hydrophobic tails facing inward toward each other: This is correct. The plasma membrane is composed of a phospholipid bilayer where the hydrophobic (water-fearing) tails face inward, shielded from water, while the hydrophilic (water-loving) heads face outward towards the aqueous environment inside and outside the cell.

3. Double layer with hydrophilic heads facing inward toward each other: This is incorrect. If the hydrophilic heads faced inward toward each other, the hydrophobic tails would be exposed to the aqueous environment, which is energetically unfavorable.

4. Double layer with phospholipids on the outside and proteins on the: This is incomplete and incorrect. While proteins are indeed embedded within or associated with the phospholipid bilayer, the description does not accurately represent the arrangement of the phospholipids themselves.

Summary: The phospholipids in the plasma membrane are arranged in a double layer with the hydrophobic tails facing inward toward each other, forming a bilayer that provides a stable barrier between the interior and exterior of the cell.