AP BIOLOGY

Detailed explanation-1: -Mass flow or bulk flow is the movement down a pressure gradient ( a pressure gradient in plants is observed due to variations in solute concentration) or temperature gradient of substances in bulk or in masses. Xylem and phloem in plants play a similar role as veins and arteries in animals.

Detailed explanation-2: -In general, bulk flow in plant biology typically refers to the movement of water from the soil up through the plant to the leaf tissue through xylem, but can also be applied to the transport of larger solutes (e.g. sucrose) through the phloem.

Detailed explanation-3: -Assertion : Mass or bulk flow is the movement of substance en masse from one point to another, as a result of pressure difference between the two points. Reason: It can be achieved only through positive hydrostatic pressure.

Detailed explanation-4: -This phenomenon is also referred to as the mass flow hypothesis. It is the process of water movement via xylem tissue from the soil to the leaves and other parts of the plant. Mass flow term can also be used in reference to the flow of bulky materials like sucrose through the phloem.

Detailed explanation-5: -Water and minerals, and food are generally moved by a mass or bulk flow system.