Question
Which of the following is correct? a. Lipids form channels in the cell membrane. b. The plasma membrane is a single layer of phospholipid c. Hydrophobic tails of phospholipids in the cell membrane contact the cytoplasm. d. Hydrophilic heads of phospholipids in the cell membrane contact the cytoplasm.
Answer
3.4
(299 Votes)
Anna
Master · Tutor for 5 years
Answer
D
Explanation
The phospholipids in the cell membrane are arranged in two layers, known as a phospholipid bilayer. Each molecule has a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic heads are attracted to the aqueous cytoplasm and the extracellular fluid while the hydrophobic tails face each other. 1. Option A is incorrect because the channels within the cell membrane are typically made of proteins, not lipids.2. Option B is wrong because the plasma membrane is not composed of a single layer, but instead is double-layered structure (bilayer) of phospholipids.3. Option C is also wrong as The hydrophobic tails of phospholipids face towards each other, not towards the cytoplasm.4. Option D is correct as The hydrophilic heads of phospholipids, because being 'water-loving', face outwards and come into contact with the watery environments both outside the cell (extracellular fluid) and inside the cell (cytoplasm).