Question

Cell membrane contains
(A) Alternate layers of phospholipids and coline.
(B) Double layers of phospholipids.
(C) Double layers of phospholipids with polar ends projected outside.
(D) Double layers of phospholipids with polar ends projected inside.

Answer 1

Hint: The plasma membrane is another name for the cell membrane. It separates the interior and exterior of a cell. It enables the cell to have controlled interactions with its surroundings. Lipids, proteins, and carbohydrates make up its composition. These carbohydrates are attached to lipids and proteins. The plant cell also has a cell wall in addition to the cell membrane.

Complete step by step solution:
Two phospholipids layers, placed next to one another, make up the plasma membrane. Phospholipids molecules with a hydrophilic (water-loving) head and a hydrophobic (water-repellent) tail make up each layer. The heads of the phospholipids point outward. One of the layers is exposed to the interior of the cell, while the other layer is exposed to the exterior of the cell. The phosphate group is drawn to the water in the intracellular fluid because it is polar and hydrophilic.

Hence, the cell membrane contains double layers of phospholipids with polar ends projected outside.
Correct Option: (C) Double layers of phospholipids with polar ends projected outside.

Note: Small molecules can only completely pass through the cell membrane because of its semi-permeable nature. Large or highly charged molecules cannot flow through it. If the hydrophobic molecules are small enough, they can readily pass through the plasma membrane because, like the interior of the membrane, they dislike water. However, hydrophilic molecules, which love water like the membrane's surface does, are unable to cross the plasma membrane on their own, at least not without assistance.