The cell membrane is composed of .........

The plasma membrane and the membranes of organelles are primarily composed of which substance?

$A$ boy is studying the transport of a certain type of molecule into a cell. He finds that the transport slows down when the cells are poisoned with a chemical that inhibits energy production. Under normal circumstances,the molecules studied by the boy are probably transported by

Assertion : $A$ cell membrane shows fluid behaviour.
Reason : $A$ membrane is a mosaic or composite of diverse lipids and proteins.

Identify the structures marked as $A, B, C$ and $D$ with respect to the fluid mosaic model of the plasma membrane.

What is true about the fluid-mosaic model of the cell membrane?