Question

1. when a hydrophilic substance crosses the cell membrane from an area of high concentration to low concentration, it is called

a. co - transport
b. active transport
c. passive transport
d. osmosis

Explanation:

• Option a: Co - transport is a type of active transport that involves the simultaneous transport of two substances, and it is not the general term for transport from high to low concentration for hydrophilic substances.
• Option b: Active transport moves substances from low to high concentration (against the gradient) and requires energy, so this is incorrect.
• Option c: Passive transport is the movement of substances from an area of high concentration to low concentration (down the concentration gradient) and does not require energy. Hydrophilic substances can cross the cell membrane via passive transport (e.g., facilitated diffusion for some hydrophilic substances), so this matches the description.
• Option d: Osmosis is the diffusion of water across a selectively permeable membrane, not the general transport of hydrophilic substances (other than water) from high to low concentration.

Answer:

c. Passive transport