Most signal molecules
A) bind to specific sites on receptor proteins in a membrane.
B) are water-soluble.
C) are able to pass through the plasma membrane by active transport.
D) A and B only
E) A, B, and C
Answer: D
Most signal molecules
A) bind to specific sites on receptor proteins in a membrane.
B) are water-soluble.
C) are able to pass through the plasma membrane by active transport.
D) A and B only
E) A, B, and C
Answer: D