For questions 1-10, fill in the blank with the letter of the description that best matches the term.

descriptions

a. a type of neuron that sends information away from the central nervous system to muscles or glands
b. a type of neuron that sends information from the sensory receptors toward the central nervous system
c. long fibers that carry signals away from the cell body
d. the fatty material surrounding some axons
e. short, highly branched fibers that carry signals toward the cell body
f. gaps in the myelin sheath
g. the space between two cells
h. a type of neuron that sends information between sensory and motor neurons
i. the reversal of the electrical potential in the plasma membrane of a neuron
j. a type of chemical released from the tip of an axon into the synaptic cleft when a nerve impulse arrives

1. axon (1 point)

2. dendrite (1 point)

3. synaptic cleft (1 point)

4. efferent neuron (1 point)

5. myelin sheath (1 point)

6. neurotransmitter (1 point)

7. afferent neuron (1 point)

8. node of ranvier (1 point)

9. action potential (1 point)

10. interneuron (1 point)

The correct answers are:

1. Axon                    ⇔ (C)
2. Dendrite              ⇔ (E)
3. Synaptic cleft      ⇔ (G) 
4. Efferent neuron   ⇔ (A) 
5. Myelin sheath     ⇔ (D) 
6. Neurotransmitter ⇔ (J)
7. Afferent neuron   ⇔ (B)
8. Node of Ranvier  ⇔ (F)
9. Action potential    ⇔ (I)
10. Interneuron        ⇔ (H)

Explanations:
(1) In a neuron, Axon is the long thread-like part (fiber) of a nerve cell along which impulses are conducted/passed from the cell body to other cells (neurons). Therefore, from the options given, the best suited sentence is "Long fibers that carry signals away from the cell body." (C)
Hence, 1. Axon ⇔ (C) Long fibers that carry signals away from the cell body

(2) In a neuron, Dendrite is a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body. Therefore, from the options given, the best suited sentence is "Short, highly branched fibers that carry signals toward the cell body." (E)
Hence, 2. Dendrite ⇔ (E) Short, highly branched fibers that carry signals toward the cell body.

(3) Synaptic cleft is the space between neurons at a nerve synapse across which a nerve impulse is transmitted by a neurotransmitter. It is also called synaptic gap. Therefore, from the options given, the best suited sentence is "The space between two cells." (G)
Hence, 3. Synaptic cleft ⇔ (G) The space between two cells.

(4) Efferent neuron is a neuron that conducts impulses outwards from the brain or the spinal cord to the muscles or organs throughout the body. Therefore, from the options given, the best suited sentence is "A type of neuron that sends information away from the central nervous system to muscles or glands." (A)
Hence, 4. Efferent neuron ⇔ (A) A type of neuron that sends information away from the central nervous system to muscles or glands.

(5) Myelin sheath is the fatty, insulating covering that surrounds an axon with multiple spiral layers of myelin. The main purpose of a myelin sheath is to increase the speed at which impulses propagate along the myelinated fiber. Therefore, from the options given, the best suited sentence is "The fatty material surrounding some axons." (D)
Hence, 5. Myelin sheath ⇔ (D) The fatty material surrounding some axons.

(6) Neurotransmitter is a chemical substance which is released at the end of a nerve fibre by the arrival of a nerve impulse and, by diffusing across the synapse or junction, effects the transfer of the impulse to another nerve fibre, a muscle fibre, or some other structure. Therefore, from the options given, the best suited sentence is "A type of chemical released from the tip of an axon into the synaptic cleft when a nerve impulse arrives." (J)
Hence, 6. Neurotransmitter ⇔ (J) A type of chemical released from the tip of an axon into the synaptic cleft when a nerve impulse arrives.

(7) Afferent neuron is a neuron conducting impulses inwards to the brain or spinal cord from muscles or organs throughout the body. Therefore, from the options given, the best suited sentence is "A type of neuron that sends information from the sensory receptors toward the central nervous system." (B)
Hence, 7. Afferent neuron ⇔ (B) A type of neuron that sends information from the sensory receptors toward the central nervous system.

(8) Node of Ranvier, in a neuron, is a gap in the myelin sheath of a nerve, between adjacent Schwann cells. Therefore, from the options given, the best suited sentence is "Gaps in the myelin sheath." (F)
Hence, 8. Node of Ranvier ⇔ (F) Gaps in the myelin sheath.

(9) Action potential is the change in electrical potential associated with the passage of an impulse along the membrane of a nerve cell or a muscle cell. Therefore, from the options given, the best suited sentence is "The reversal of the electrical potential in the plasma membrane of a neuron." (I)
Hence, 9. Action potential ⇔ (I) The reversal of the electrical potential in the plasma membrane of a neuron.

(10) Interneuron is neuron that transmits impulses between sensory neurons and the motor neurons. It, itself, is neither a motor neuron nor a sensory neuron. Therefore, from the options given, the best suited sentence is "A type of neuron that sends information between sensory and motor neurons." (H)
Hence, 10. Interneuron ⇔ (H) A type of neuron that sends information between sensory and motor neurons.