Question

Where are ion carriers located?
A. Nucleus
B. Cell wall
C. Cellular space
D. Plasma membrane

Answer 1

Hint: Ion carriers are proteins that help in the transportation of ions. They help in maintaining the ionic concentration in the cell. They usually transport ions across their respective gradients. In a plant cell, this layer is present below the cell wall.

Complete answer: The plasma membrane is a living membrane. Due to this, it is selective in nature. It means that it allows all solvent and only some solutes to pass through it. According to the Fluid mosaic model, the plasma membrane is made up of bilayered phospholipids. This phospholipid layer has two types of proteins over it. These proteins are tunnel proteins and Integral proteins. The tunnel proteins help in passive transportation. The active transportation occurs through integral proteins. The integral proteins are also known as intrinsic proteins. They are the movable ion carrier proteins. These proteins form a protein-ion complex with the ion and then, they transport them against the concentration gradient with the help of ATP. In this way, the plasma membrane is able to selectively reabsorb ions and transport them. The nucleus or the nuclear membrane does not have any ion carriers. The cell wall is a dead and fully permeable membrane. There are no ion carriers in the cellular space as well.
Hence, the correct answer is option D.

Note: The plasma membrane is the outermost layer of the animal cell. It is made up of proteins and lipids. It is also present in plant cells, but it is not an outermost layer. The plasma membrane in a plant cell is surrounded by another membrane called the cell wall.