Kaplan Ch. 8 - Membranes

Question 1

When does simple diffusion occur?

Answer 1

ONLY when molecules flow down concentration gradients directly across the membrane, meaning they must be able to freely cross the membrane for passive diffusion to occur.

Question 2

What is facilitated diffusion?

Answer 2

Simple diffusion down a concentration gradient for molecules that are IMPERMEABLE to the membrane, requires membrane transport or channel proteins

Question 3

Primary active transport

Answer 3

Uses ATP or other source of energy to directly power the transport of molecules across a membrane

Question 4

Secondary active transport

Answer 4

Couples transport

Uses energy to transport molecules across a membrane but there is no direct coupling to ATP hydrolysis. Instead energy released from one molecule moving down its concentration gradient is used to drive another molecule up its concentration gradient.