NEET 2023 Biology Solved Paper Code C4 (Manipur)

The mass flow hypothesis, also known as the pressure-flow hypothesis, is a model used to explain the movement of sap through the phloem in plants.
(A) Mass flow is faster than diffusion - True. Mass flow is faster because it is driven by pressure differences, while diffusion relies on concentration gradients which usually results in slower movement.
(B) Mass flow is the result of pressure difference between the end points - True. According to the mass flow hypothesis, the movement of sap is driven by a pressure gradient between the source (where sugars are produced by photosynthesis) and the sink (where sugars are used).
(C) Different substances involved in mass flow move at different paces - False. In mass flow, all the components of the sap, including sugars, hormones, and minerals, move together at the same pace due to the pressure gradient.
(D) Mass flow can result through either a positive or a negative hydrostatic pressure gradient - True. The flow of sap in phloem can be both upward and downward, depending on where the source and sink are located, meaning it can follow both positive (from high to low pressure) and negative (from low to high pressure, which requires energy) pressure gradients.