A ____ is an extracellular signaling molecule that exerts its effect at very low concentrations.
A) statolith
B) protein receptor
C) plant hormone
D) cytochrome
E) phytochrome

Question

A ____ is an extracellular signaling molecule that exerts its effect at very low concentrations.  
A) statolith
B) protein receptor
C) plant hormone
D) cytochrome
E) phytochrome

Quizplus · Accepted Answer

The description given matches that of a plant hormone. Plant hormones are extracellular signaling molecules that exert their effects in very low concentrations, sometimes in parts per million or parts per billion.

A ____ Is an Extracellular Signaling Molecule That Exerts Its