Question

What is hydrostatic pressure (positive and negative with every day examples) and its role in bulk transport?

Answer 1

The pressure exerted by a fluid (gas or liquid) at equilibrium due to the force of gravity is called hydrostatic pressure. The hydrostatic pressure existing in roots which push the water up in xylem vessels. Hydrostatic pressure increases with depth because of the increasing weight of fluid exerting downward force from above. This change in hydrostatic pressure with depth is known as hydrostatic pressure gradient.

The positive hydrostatic pressure gradient: In plants, the leaves have large amount of stored food in the form of sugar or we can say the source has 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 rest of the plants.

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

The toilet in your house: The buoy inside it is attached to a watervalve to stop water when the toilet is full.