Question

question simple diffusion is best described as substances ________. answer

• moving actively against a concentration gradient
• moving actively down a concentration gradient
• moving passively down a concentration gradient
• moving passively against a concentration gradient
• i dont know yet

Explanation:

To solve this, we recall the concept of simple diffusion: it is a passive transport process (no energy required) where substances move from an area of higher concentration to lower concentration (down the concentration gradient).

• "moving actively against a concentration gradient" is incorrect as active transport (not simple diffusion) uses energy and moves against the gradient.
• "moving actively down a concentration gradient" is incorrect because simple diffusion is passive, not active.
• "moving passively down a concentration gradient" matches the definition of simple diffusion (passive, down the concentration gradient).
• "moving passively against a concentration gradient" is incorrect as passive processes don't move against the gradient (that requires energy, active transport).

Answer:

C. moving passively down a concentration gradient