Good vision depends on adequate intake of carotene-rich food. Select the correct combination of statements from the following: (a) Vitamin A derivatives are formed from carotene. (b) The photopigments are embedded in the membrane discs of the inner segment. (c) Retinal is a derivative of vitamin A. (d) Retinal is a light-absorbing part of all the visual photopigments.

The specific receptors for neurotransmitters in a synapse are present on __________.

Succinylcholine acts as a neuromuscular blocker by mimicking which neurotransmitter at the neuromuscular junction?

Which of the following statements about neurons are correct? 1. Myelin sheath increases the speed of nerve impulse propagation. 2. Nodes of Ranvier assist in saltatory conduction. 3. Neurotransmitters are released at axon terminals. 4. Dendrites carry nerve impulses away from the cell body.