Question

The transport of water through xylem and transport of organic substances through phloem are achieved respectively by

• A. negative hydrostatic pressure as in the working of a garden hose and positive hydrostatic pressure as a suction through a straw
• B. positive hydrostatic pressure as in the working of a garden hose and negative hydrostatic pressure gradient as a suction through a straw
• C. positive hydrostatic pressure as a suction through a straw and negative hydrostatic pressure as the working of a garden hose
• D. negative hydrostatic pressure gradient as a suction through a straw and positive hydrostatic pressure gradient as the working of a garden hose.

Answer 1

The correct option is D negative hydrostatic pressure gradient as a suction through a straw and positive hydrostatic pressure gradient as the working of a garden hose.

The positive hydrostatic pressure gradient: In plants, the leaves have a large amount of stored food in the form of sugar or we can say the source has a high solute concentration. As a result, water moves from neighbouring cells into the leaves. This creates a pressure gradient and the water moves out of the source along with sugars thereby transporting sugars to the rest of the plants.

The negative hydrostatic pressure gradient: In plants, roots absorb water and minerals from the soil. This means that soil has a high solute concentration still the water enters into the root hairs along with minerals.