Question

According to Munch theory, the cause of flow of soluble substance is

• A. Protoplasmic flow
• B. Mass flow due to reduction in turgor pressure
• C. Diffusion
• D. None of the above

Answer 1

Answer: (B)

Mass flow due to reduction in turgor pressure

At the site of synthesis i.e., leaves, sugars are synthesized, which leads to an increase in osmotic pressure inside leaf mesophyll due to which water from xylem moves inside mesophyll cells. At the site of sugar utilisation, sugars are used up and so water moves from inside the cells to the xylem vessels. The difference in sugar concentration at source and sink creates a pressure gradient and sugars move in bulk from source to sink.