Question

Question: Based on Figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?

1. decreasing extracellular sucrose concentration
2. decreasing extracellular pH
3. decreasing cytoplasmic pH
4. Adding a substance that makes the membrane more permeable to hydrogen ions

Short answer

1. The statement “decreasing extracellular sucrose concentration” is false.
2. The statement “decreasing extracellular pH” is true.
3. The statement “decreasing cytoplasmic pH” is false.
4. The statement “Adding a substance that makes the membrane more permeable to hydrogen ions” is false.

Step-by-step solution

Co-transport

Cotransport is the mechanism that involves the movement of a substance towards the concentration gradient and another molecule against the concentration gradient. There are two types in it such as symport and antiport.

Explanation of option ‘(A)’

The exchange of sucrose happens in return for the exchange of hydrogen ions. The reduction in sucrose concentration cannot speed up this reaction.

Thus, decreasing the extracellular concentration of sucrose cannot increase the transport of sucrose into the plant cell.

Therefore, the given statement is false.

Explanation of option ‘(B)’

The extracellular pH is the influencing factor in the sucrose transporter activities in plant cells. The transport process increases with a decrease in extracellular pH.

Thus, the sucrose transport mechanism depends on the decrease in the pH present outside the plant cells.

Therefore, the given statement is true.

Explanation of option ‘(C)’

The changes in criteria such as extracellular pH, redox property, and oxidizing compounds determine the plant sucrose transporters.

Thus, the cytoplasmic pH does not facilitate the transport of sucrose into the plant cell.

Therefore, the given statement is false.

Explanation of option ‘(D)’

The presence of an appropriate level of hydrogen is the reason for the facilitation of sucrose transport. The necessity of additional substance is unnecessary in this mechanism.

Thus, there is no need to increase the permeability of the membrane by using additional substances.

Therefore, the given statement is false.