Question

which type of transport requires energy to move molecules against the concentration gradient?
a) osmosis
b) facilitated diffusion
c) diffusion
d) active transport

Explanation:

• Option A (Osmosis): Osmosis is the diffusion of water across a semi - permeable membrane, moving from an area of lower solute concentration to higher solute concentration (or along the water concentration gradient). It is a passive process and does not require energy.
• Option B (Facilitated Diffusion): Facilitated diffusion is a type of passive transport where molecules move across the cell membrane with the help of transport proteins, but still along the concentration gradient (from high to low concentration). No energy is required.
• Option C (Diffusion): Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration (along the concentration gradient) and is a passive process that does not need energy input.
• Option D (Active Transport): Active transport is defined as the movement of molecules across a cell membrane from an area of lower concentration to an area of higher concentration (against the concentration gradient). This process requires energy (usually in the form of ATP) to occur.

Answer:

D) Active Transport