Question

Assertion: The plasma membrane is selectively permeable.
Reason: It allows some solute to pass through it readily along with the solvents.
(a)Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
(b)Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
(c) Assertion is correct but Reason is incorrect.
(d) Both Assertion and Reason are incorrect.

Answer 1

Plasma membrane for the cell membrane is a semi-permeable membrane of a cell that is surrounded by cytoplasm and nucleoplasm. It separates the cell from the surrounding interstitial fluid from the main components of the extracellular fluid.

Complete answer:
The plasma membrane or Cell membrane is the outer covering of the cells and is present below the cell wall in plant cells. it constitutes a phospholipid bilayer structure that is embedded with proteins and gives a mosaic-like appearance. It is a selectively permeable membrane which means half permeable, that is, it allows free transport of solvent like water across it and does not allow the free transport of solute particles through the plasma membrane. The movement of the particles across the membrane is either passive which occurs without the input of cellular energy or activity which is required by the cells to expend energy in transport.

Additional information:
Plasma membrane constitutes A leopard bilayer which includes cholesterol that maintains their fluidity at various temperatures. It contains membrane proteins which include integral proteins that serve as a membrane transporter and the peripheral proteins that attach to the outer side of the cell membrane loosely and act as an enzyme in shaping the cell. It controls the movement of substances in and out of the cells and is selectively permeable to ions and organic molecules. They help in various cellular processes such as ion conductivity, cell signaling, and cell division which serve as the attachment for several extracellular structures which include the cell wall and the carbohydrate layer known as the glycocalyx.

So, the correct answer is 'Both Assertion and Reason are correct and Reason is the correct explanation for Assertion'.

Note: The plasma membrane is made up of a double layer of phospholipids that helps in the separation of the cell from the outside world and contains a protein that provides several critical functions. To describe the structure of a cell membrane Singer and Nicolson's fluid mosaic model is preferred.