Question

Explain pressure flow hypothesis of translocation of sugars in plants.

Answer 1

According to the pressure flow hypothesis, food is prepared in the plant leaves in the form of glucose. Before moving into the source cells present in the phloem, the prepared food is converted into sucrose. Water moves from the xylem vessels into the adjacent phloem, thereby increasing the hydrostatic pressure in the phloem. Consequently, the sucrose moves through the sieve cells of the phloem. The sucrose already present in the sink region is converted into starch or cellulose, thereby reducing the hydrostatic pressure in the sink cells. Hence, the pressure difference created between the source and the sink cells allows sugars to be translocated from the former to the latter. This starch or cellulose is finally removed from the sink cells through active transport.

Hope this will help you..... ✌

Answer 2

Pressure flow hypothesis states that the sugars that are produced in the leaves are translocated along the pressure gradient through the phloem.

Explanation:

• The production of sugars as a result of photosynthesis in the leaves results in the high pressure at the source .i.e. the leave.
• Consumption of sugars by the cells at other parts where photosynthesis doesn't takes place results in lower pressure at the sink .ie. non photosynthetic parts.
• The food or the sugar produced in the source move from the source to the sink along the pressure gradient i.e. from the region of higher pressure to the region of lower pressure.
• This Hypothesis clearly explains the mechanism of translocation of sugar from the leaves to other distant parts of the plant through phloem.