What is most likely to happen to an animal's target cells that lack receptors for local regulators?

A) They might compensate by receiving nutrients via a factor. B) They could develop normally in response to neurotransmitters instead. C) They could divide but never reach full size. D) They might not be able to multiply in response to growth factors from nearby cells. E) Hormones would not be able to interact with target cells.

Which of the following is characterized by a cell releasing a signal molecule into the environment, followed by a number of cells in the immediate vicinity responding?

A) hormonal signaling B) autocrine signaling C) paracrine signaling D) endocrine signaling E) synaptic signaling

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

A) the active site of an allosteric enzyme that binds to a specific substrate. B) tRNA specifying which amino acids are in a polypeptide. C) a metabolic pathway operating within a specific organelle. D) an enzyme having an optimum pH and temperature for activity. E) an antibody in the immune system.