Neural Control and Coordination – Neuron as Structural and Functional Unit of Neural System: NEET MCQs with Answers

15 free questions on Neural Control and Coordination – Neuron as Structural and Functional Unit of Neural System for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Neuron as Structural and Functional Unit of Neural System

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Question 1

Previous-year question
Match List-I with List-II. [Re-NEET 2024]
List-I:
A. Schwann cells
B. Synaptic knob
C. Bipolar neurons
D. Multipolar neurons
List-II:
I. Neurotransmitter
II. Cerebral cortex
III. Myelin sheath
IV. Retina
  1. A-III, B-I, C-IV, D-II
  2. A-I, B-IV, C-II, D-III
  3. A-IV, B-III, C-II, D-I
  4. A-II, B-III, C-I, D-IV
Show answer
Answer: (A) A-III, B-I, C-IV, D-II
Explanation: Schwann cells form the myelin sheath around axons in the PNS (A-III). Synaptic knobs at axon terminals contain synaptic vesicles filled with neurotransmitter (B-I). Bipolar neurons are found in the retina of the eye (C-IV), and multipolar neurons in the cerebral cortex (D-II).

Question 2

Previous-year question
Match the items in List-I with those in List-II. [Re-NEET 2022]
List-I:
(a) Multipolar neuron
(b) Bipolar neuron
(c) Myelinated nerve fibre
(d) Unmyelinated nerve fibre
List-II:
(i) Somatic neural system
(ii) Cerebral cortex
(iii) Retina of eye
(iv) Spinal nerves
  1. (a) – (iii), (b) – (i), (c) – (iv), (d) – (ii)
  2. (a) – (ii), (b) – (iv), (c) – (iii), (d) – (i)
  3. (a) – (ii), (b) – (iii), (c) – (i), (d) – (iv)
  4. (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)
Show answer
Answer: (D) (a) – (ii), (b) – (iii), (c) – (iv), (d) – (i)
Explanation: Multipolar neurons are found in the cerebral cortex and bipolar neurons in the retina of the eye. Myelinated nerve fibres occur in spinal and cranial nerves, whereas unmyelinated fibres are commonly found in the autonomous and somatic neural systems. Hence (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i).

Question 3

Previous-year question
The junction between the axon of one neuron and the dendrite of the next is called [AIPMT 1999]
  1. a junction point
  2. a synapse
  3. a joint
  4. a constant bridge
Show answer
Answer: (B) a synapse
Explanation: The end-to-end position of the axon of one neuron and the dendrites of another neuron is called the synapse. It is formed by the membranes of a pre-synaptic and a post-synaptic neuron, which do not actually touch — the minute separating gap between them is the synaptic cleft.

Question 4

Previous-year question
Which of the following is regarded as a unit of nervous tissue? [AIPMT 1999]
  1. Myelin sheath
  2. Axons
  3. Dendrites
  4. Neurons
Show answer
Answer: (D) Neurons
Explanation: Nervous tissue is made up of nerve cells, the repeating units, which are also called neurons. Each neuron has a cell body or cyton and two kinds of cell process — dendrons, which come out from the cyton, and the axon, an elongated nerve fibre.

Question 5

Previous-year question
An action potential in the nerve fibre is produced when positive and negative charges on the outside and the inside of the axon membrane are reversed, because [AIPMT 2000]
  1. more potassium ions enter the axon as compared to sodium ions leaving it
  2. more sodium ions enter the axon as compared to potassium ions leaving it
  3. all potassium ions leave the axon
  4. all sodium ions enter the axon
Show answer
Answer: (B) more sodium ions enter the axon as compared to potassium ions leaving it
Explanation: When a nerve fibre is stimulated, its membrane becomes more permeable to sodium ions, so more sodium ions enter the axon than potassium ions leave it. As a result, the positive and negative charges on the outside and inside of the membrane are reversed, and the membrane with reversed polarity is said to be depolarised.

Question 6

Previous-year question
Which cells do NOT form a layer and remain structurally separate? [AIPMT 2001]
  1. Epithelial cells
  2. Muscle cells
  3. Nerve cells
  4. Gland cells
Show answer
Answer: (C) Nerve cells
Explanation: Nerve cells do not form layers and also remain structurally separate from each other, though they communicate with one another through synapses. Nerve cells or neurons are the cells specialised to conduct an electrochemical current, and nerve tissue is made up of these cells together with supporting cells.

Question 7

Previous-year question
Which of the following statements is correct about the node of Ranvier? [AIPMT 2002]
  1. Axolemma is discontinuous
  2. Myelin sheath is discontinuous
  3. Both neurilemma and myelin sheath are discontinuous
  4. Covered by myelin sheath
Show answer
Answer: (B) Myelin sheath is discontinuous
Explanation: An ordinary neuron has a soma or cyton and a long thread called the axon, which is enclosed in a multilayered myelin sheath. The myelin sheath is interrupted at the spaces between Schwann cells to form gaps, and these gaps are called nodes of Ranvier; they create the condition that speeds up nerve impulses (saltatory conduction).
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Question 8

Previous-year question
What used to be described as Nissl's granules in a nerve cell is now identified as [AIPMT 2003]
  1. ribosomes
  2. mitochondria
  3. cell metabolites
  4. fat granules
Show answer
Answer: (A) ribosomes
Explanation: The main cell body of a neuron is called the cyton or soma. It contains a large, centrally located nucleus, mitochondria, Golgi bodies, rough endoplasmic reticulum, lysosomes and fat globules, and also Nissl's granules or neurofibrils. These are masses of ribosomes and rough endoplasmic reticulum, and are engaged in protein synthesis.

Question 9

Previous-year question
In the resting state of the neural membrane, diffusion due to concentration gradients, if allowed, would drive [AIPMT 2004]
  1. K⁺ into the cell
  2. K⁺ and Na⁺ out of the cell
  3. Na⁺ into the cell
  4. Na⁺ out of the cell
Show answer
Answer: (C) Na⁺ into the cell
Explanation: In the resting nerve fibre, the cytoplasm inside the axon has a high concentration of K⁺ and a low concentration of Na⁺, in contrast to the fluid outside the axon. Therefore, if diffusion were to occur along the concentration gradient, Na⁺ would enter the fibre.

Question 10

Previous-year question
Parkinson's disease (characterised by tremors and progressive rigidity of limbs) is caused by degeneration of brain neurons that are involved in movement control and make use of the neurotransmitter [AIPMT 2005]
  1. acetylcholine
  2. norepinephrine
  3. dopamine
  4. GABA
Show answer
Answer: (C) dopamine
Explanation: The abnormal release of the neurotransmitter dopamine leads to Parkinson's disease in humans. It is caused by the degeneration of those brain neurons that are involved in the control of movement.

Question 11

Previous-year question
Four healthy people in their twenties got involved in injuries resulting in damage and death of a few cells of the following. Which of the cells are least likely to be replaced by new cells? [AIPMT 2005]
  1. Osteocytes
  2. Malpighian layer of the skin
  3. Liver cells
  4. Neurons
Show answer
Answer: (D) Neurons
Explanation: Neuron cells are least likely to be replaced by new cells. These cells are specialised to conduct an electrochemical current, and they lack the capability of division because they are arrested at the G₀ phase of the cell cycle.

Question 12

Previous-year question
Which one of the following does NOT act as a neurotransmitter? [AIPMT 2006]
  1. Acetylcholine
  2. Epinephrine
  3. Norepinephrine
  4. Cortisone
Show answer
Answer: (D) Cortisone
Explanation: Cortisone does not act as a neurotransmitter; it is a corticosteroid, itself biologically inactive, formed naturally in the adrenal cortex from the active hormone cortisol. Acetylcholine is secreted from nerve endings, while epinephrine and norepinephrine are secreted from the adrenal medulla and also act as neurotransmitters.

Question 13

Previous-year question
Which one of the following pairs of structures distinguishes a nerve cell from other types of cell? [AIPMT 2007]
  1. Perikaryon and dendrites
  2. Vacuoles and fibres
  3. Flagellum and medullary sheath
  4. Nucleus and mitochondria
Show answer
Answer: (A) Perikaryon and dendrites
Explanation: A nerve cell consists of a cell body (perikaryon) containing the nucleus, Nissl's granules and dendrites, together with an axon. These are highly specialised cells, and it is the perikaryon-with-dendrites combination that distinguishes them from other cell types.

Question 14

Previous-year question
During the transmission of a nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has which type of electric charge? [AIPMT 2007]
  1. First negative, then positive and again back to negative
  2. First positive, then negative and continue to be negative
  3. First negative, then positive and continue to be positive
  4. First positive, then negative and again back to positive
Show answer
Answer: (A) First negative, then positive and again back to negative
Explanation: During the transmission of a nerve impulse, the potential on the inner side of the plasma membrane is first negative (resting state), then becomes positive as depolarisation occurs, and then returns to negative again by repolarisation.

Question 15

Previous-year question
During the propagation of a nerve impulse, the action potential results from the movement of [AIPMT 2008]
  1. K⁺ ions from extracellular fluid to intracellular fluid
  2. Na⁺ ions from intracellular fluid to extracellular fluid
  3. K⁺ ions from intracellular fluid to extracellular fluid
  4. Na⁺ ions from extracellular fluid to intracellular fluid
Show answer
Answer: (D) Na⁺ ions from extracellular fluid to intracellular fluid
Explanation: When a stimulus of adequate strength is applied to a polarised membrane, the permeability of the membrane to Na⁺ increases at that point. The sodium ion channels then permit the influx of Na⁺ by diffusion, from the extracellular fluid into the intracellular fluid.

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