Question

multiple choice question
during ____, molecules are moved across a plasma membrane against the molecules’ concentration gradient.

• osmosis
• filtration
• diffusion
• passive transport
• active transport

Explanation:

• Osmosis is the movement of water across a semipermeable membrane down its concentration gradient (from high to low water concentration, or low to high solute concentration), so it's passive and not against the gradient.
• Filtration is the movement of substances due to hydrostatic pressure, usually down a pressure gradient, not against a concentration gradient.
• Diffusion is the movement of molecules from an area of high concentration to low concentration (down the concentration gradient), so it's passive.
• Passive transport includes processes like diffusion, osmosis, and filtration, all of which move substances down their concentration or pressure gradients, not against.
• Active transport requires energy (like ATP) and moves molecules across the plasma membrane against their concentration gradient (from low to high concentration).

Answer:

E. active transport