One of a variety of molecules within axon terminals that are released into the synaptic cleft in response to a nerve impulse and that change the membrane potential of the postsynaptic neuron.

Correct Answer: B

Rationale: A neurotransmitter is released from axon terminals into the synaptic cleft, altering postsynaptic membrane potential. Epinephrine is a hormone, neurology is a field, and sympathetic is a system.

Correct Answer: B

Rationale: A hyperpolarizing graded potential (e.g., IPSP) makes the membrane more negative, reducing the likelihood of an action potential. Depolarizing is excitatory, others are incorrect terms.

Correct Answer: C

Rationale: Effectors are tissues that respond to neural signals, such as glands (secreting hormones) and muscles. Cranial nerves and spinal cord are neural, and the brain is CNS.

Correct Answer: A

Rationale: Organs are like chapters, each a major functional unit contributing to the organism (book). Cells are words, tissues are sentences, and organ systems are sections.

Correct Answer: B

Rationale: Nissl bodies are rough endoplasmic reticulum in neurons, synthesizing proteins. Mitochondria produce energy, lysosomes degrade waste, and Golgi processes proteins.