Filtration is defined as

Filtration is defined as

• A. Transport of a solution through a filter, provided the membrane is permeable to water
• B. Movement of water against its gradient
• C. Absorption of nutrients by capillaries
• D. Secretion of plasma into tissue

Answer: (A)

Filtration is the transport of a solution through a filter, provided the membrane is permeable to water. This means fluid is driven through a porous barrier by a pressure difference, allowing water and small solutes that can pass through the pores to move along with the flow. It relies on the barrier’s permeability to water and on pressure, not on solute concentration gradients. The other descriptions refer to separate processes: moving water against its gradient isn’t filtration, absorption by capillaries is uptake into the bloodstream, and secretion into tissue describes a distinct transport/secretion process rather than the general filtration mechanism.

Filtration is the transport of a solution through a filter, provided the membrane is permeable to water. This means fluid is driven through a porous barrier by a pressure difference, allowing water and small solutes that can pass through the pores to move along with the flow. It relies on the barrier’s permeability to water and on pressure, not on solute concentration gradients. The other descriptions refer to separate processes: moving water against its gradient isn’t filtration, absorption by capillaries is uptake into the bloodstream, and secretion into tissue describes a distinct transport/secretion process rather than the general filtration mechanism.