After one frog’s heart was stimulated, an extract of fluid from that heart made a second frog’s heart beat slower. What conclusion did Otto Loewi draw from these results?

Which of the following hormones is a peptide?

Which class of hormones will most likely bind to a cytosolic or nuclear receptor?

Why does caffeine exert stimulant actions?

What is the function of acetylcholinesterase (AChE)?

Why does the fovea provide the clearest, most detailed visual information?

What is the function of autoreceptors?

All somatosensory inputs to the spinal cord are __________; and all motor outputs from the spinal cord are __________.

After one of the catecholamine transmitters stimulates the postsynaptic receptor, what happens to most of the transmitter molecules?

Which of the following best describes Mendel’s work with pea plants?