Question

The translocation of organic solutes in sieve tube members is supported by-
A. Root pressure and transpiration pull
B. P-proteins
C. Mass flow involving a carrier and ATP
D. Cytoplasmic streaming

Answer 1

Translocation is the process in which the food produced by the leaves transport throughout the body of the plants. Sieve tube and companion cells are responsible for translocation.

Complete answer:
The main organic solute is food prepared by leaves which is transported by sieve tube and companion cells. This process requires lots of metabolic energy.

Option A is Root pressure and transpiration pull. Root pressure and transpiration generally helps in transportation of water from roots to other parts. They do not play any role in transportation of organic material. So, this option is wrong.

Option B is P-proteins. P-protein are phloem proteins found on the wall of the phloem. P-proteins is a recent discovery and its functions are still clear. The function on p-protein is damage control and it may help in translocation but we are still not sure that it helps in transportation or not.

Option is Mass flow involving a carrier and ATP. According to mass flow hypothesis, the food formed in leaves transport very fast than transportation of water in xylem and this food flows in bulk or mass. This requires a lot of energy. They get energy by hydrolysis of ATP. So, we can say that mass flow involving an ATP and carrier helps in translocation of organic food.

Option D is cytoplasmic streaming. Cytoplasmic streaming is movement of cytoplasm inside the cell. By this, every organelle gets nutrients and proteins present in the plant. In certain single-celled organisms, it also gives the cell the ability to move. So, it helps in translocation of cells but only inside the cell.

So, the most appropriate answer is cytoplasmic streaming is what allows nutrients and proteins to move about inside a cell. In certain single-celled organisms, it also gives the cell the ability to move.

Hence, The correct answer is option (C).

Note: Some people confuse between whether p-protein helps in translocation or not. But as we already said its functions are still unclear. Cytoplasmic streaming is also correct but for a cell only, not for a plant. So, Mass flow involving a carrier and ATP is the correct option.