Question

endocytosis and exocytosis are forms of active transport. what is active transport? (1 point) the movement of molecules up a concentration gradient from low to high, using no energy the movement of molecules down a concentration gradient from high to low, using no energy the movement of molecules up a concentration gradient from low to high, using energy the movement of molecules down a concentration gradient from high to low, using energy

Explanation:

To determine the correct definition of active transport, we recall the key characteristics: active transport moves molecules against (up) the concentration gradient (from low to high concentration) and requires energy (usually ATP) because it's working against the natural flow of diffusion.

• The first option is incorrect as it says "using no energy" (active transport needs energy).
• The second option describes passive transport (down gradient, no energy, like diffusion or osmosis).
• The fourth option is also passive transport (down gradient) but incorrectly says it uses energy.
• The third option correctly states movement up the gradient (low to high) and using energy.

Answer:

C. the movement of molecules up a concentration gradient from low to high, using energy