Question

Question: Which of the following processes includes all the others?

1. osmosis.
2. diffusion of a solute across a membrane.
3. passive transport
4. transport of an ion down its electrochemical gradient

Short answer

1. The statement “osmosis” is false.
2. The statement “diffusion of a solute across a membrane” is false.
3. The statement “passive transport” is true.
4. The statement “transport of an ion down its electrochemical gradient” is false.

Step-by-step solution

Transport across membrane

The process of moving materials across the cells takes place with a specific mechanism of action. There are two types in which the transportation mechanism proceeds such as active and passive transport.

Explanation of option ‘(A)’

The mechanism of diffusion that takes place via the semi-permeable membrane is known as osmosis. It occurs from higher water potential to lower water potential.

Thus, osmosis is a special diffusion that does not require energy to drive the process. So, it comes under the category of passive transport.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The movement of molecules from the high concentration region to the low concentration region is known as diffusion.

Thus, the diffusion process happens in concentration, requiring additional energy to drive the process. So, it is also a passive mechanism.

Therefore, the given statement is false.

Explanation of option ‘(C)’

Passive transport mechanism does not require energy for the process. The passive transport mechanism includes osmosis, diffusion, and transport of ions down the electrochemical gradient.

Thus, all the other given mechanisms, such as osmosis, diffusion, and movement of ions, come under passive transport.

Therefore, the given statement is true.

Explanation of option ‘(D)’

The movement of ions down the electrochemical gradient happens in voltage-gated channels. This process does not occur against the gradient.

Thus, the transport of ions facilitates without any additional energy requirement. So, the transport of ions is the phenomenon of passive transport.

Therefore, the given statement is false.