Question

${ Na }^{ + }/{ K }^{ + }$ pump in a cell is an example of
(a) Osmosis
(b) Diffusion
(c) Passive transport
(d) Active transport

Answer 1

Hint: Sodium potassium pump is an example of energy-dependent and carrier-mediated membrane transport. It occurs with the help of carrier proteins and also with the input of energy.

Complete answer:
Transport of sodium and potassium is an example of primary active transport. The sodium-potassium pump is a type of coupled or co-transport in which the transport of one ion along the concentration gradient is coupled to the transport of another ion against the concentration gradient. Active transport is the energy-dependent and carrier-mediated uphill flow of metabolites against the concentration or electrochemical gradient and osmotic forces. It requires energy for transport. Its energy source is ATP or the ions which exhibit an electrochemical potential. Usually, sodium is present in a higher amount outside the cell, while potassium is present in a high concentration inside the cell. In this process, three sodium ions are exchanged for every two potassium ions.

Additional Information:
- Active transport is the major mechanism by which a cell maintains a constant concentration of ions and molecules inside it, in spite of the marked fluctuations in their concentrations outside.
- Active transport resembles facilitated diffusion in being stereospecific and permease- mediated. Moreover, the rates of both of them show saturation kinetics.
- At the same time, active transport differs from facilitated diffusion in that it is an enzymatic process, operating against concentration and potential gradients and osmotic forces, utilizing metabolic energy.
So, the correct answer is '(d) Active transport'

Note:
- Active transport is of three main kinds; uniport, symport, and antiport.
- Uniport is the unidirectional transport of only one kind of molecules at a time through a membrane channel.
- Symport is the simultaneous unidirectional transport of different kinds of molecules. Antiport is the simultaneous transport of different kinds of molecules in opposite directions.