Biology

Nervous System and Neurons

1,164 Questions

The nervous system and neurons section covers the structural and functional aspects of the human nervous system. Topics include nerve fibers, the myelin sheath, and sympathetic nervous system functions. This material is crucial for general science preparation in various competitive exams.

Neuron structureMyelin sheath productionSympathetic nervous systemCranial and spinal nervesParasympathetic functions

Nervous System and Neurons Questions

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

On nerve fibres, to prevent leakage of an impulse, a layer of ...... is found.

  1. Rod cells

  2. Neurilemma

  3. Axons

  4. Myelin sheath
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Myelin is an insulating layer, or sheath, that forms around nerves. It is made up of protein and fatty substances. The fat helps to insulate the axons from electrically charged atoms and molecules. The purpose of the myelin sheath is to allow electrical impulses to transmit quickly and efficiently along the nerve cells.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Which one is absent in neurons ?

  1. Neurilemma

  2. Axon

  3. Sareolemma

  4. Dendrites
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sareolemma appears to be a misspelling of sarcolemma, which is the cell membrane of muscle fibres, NOT neurons. Neurons DO have neurilemma (Schwann cell membrane), axon, dendrites. The spelling error makes option C the correct answer as the absent structure.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

In axon of a neuron, the impulse is generated by exchange of

  1. Sodium and chlorine

  2. Magnesium and chlorine

  3. Calcium and potassium

  4. Sodium and potassium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The generation and propagation of an action potential in an axon are primarily driven by the rapid influx of sodium ions and the subsequent efflux of potassium ions.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Myelin sheath is derived from

  1. Neuroglial cells

  2. Schwann cells

  3. Nerve cells

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Myelin sheath is formed by oligodendrocytes in the CNS and by Schwann cells in the peripheral nervous system. 
  • These cells wrap layer upon layer of their own plasma membrane in a tight spiral around axon. 
  • The insulating layer checks the leakage of charge and lesser stoppage points (nodes of Ranvier) leading to acceleration of the conduction and conservation of the metabolic energy.
So, the correct option is 'Schwann cells'.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

End plate junction is present between

  1. Neuron and striated muscle

  2. Neuron and neuron

  3. Muscle and muscle

  4. Both (b) and (c)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • The site of chemical communication between a nerve fibre and a muscle cell is called the end plate junction or neuromuscular junction.
  • The neuromuscular junction is analogous to the synapse between two neurons. 
  • A nerve fibre divides into many terminal branches; each terminal ends on a region of muscle fibre called the end plate. Embedded in the end plate are thousands of receptors. 
  • So, the correct option is 'Neuron and Striated muscle'.
Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

The myelin sheath around the axon is produced by which type of neurogical cells?

  1. Satellite glial cells

  2. Radial glial cells

  3. Dendrocytes

  4. Schwann cells
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation


  1. Myelin sheath is formed by oligodendrocytes in the central nervous system and by Schwann cells in the peripheral nervous system. 
  2. These cells wrap layer upon layer of their own plasma membrane in a tight spiral around axon. 
  3. The insulating layer checks the leakage of charge and lesser stoppage points (nodes of Ranvier) leading to acceleration of the conduction and conservation of the metabolic energy.
So, the correct option is 'Schwann cells'.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

During depolarisation of neuron

  1. $K^+$ channels remain open
  2. N$a^+$ gets inside through ion channels
  3. N$a^+$ gets outside through ion channels

  4. All the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During depolarization, voltage-gated sodium channels open, allowing sodium ions to rush into the neuron, which makes the interior less negative.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Synaptic vesicles are

  1. at the ends of dendrites and axons

  2. at the ends of axons only

  3. along the length of all long fibres

  4. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In a neuron, synaptic vesicles store various neurotransmitter that is released at the synapse. The release is regulated by a voltage-dependent calcium channel. Vesicles are essential for propagation nerve impulses between neurons and are constantly recreated by the cell.

So, the correct option is 'at the ends of axons only'.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Assertion : Myelinated nerve fibre are enveloped with Schwann cells, which form a myelin sheath around the axon
Reason : Unmyelinated nerve fibre is not enclosed by a Shwann cell and hence does not form a myelin sheath around the axon

  1. If both assertion and reason are true and the reason is the correct explanation of the assertion

  2. If both assertion and reason are true but reason is not the correct explanation of the assertion

  3. If assertion is true but reason is false

  4. If both assertion and reason are false
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The myelinated nerve fibers contain a myelin sheath surrounding the axons of nerve cells. While in unmyelinated nerve fibre is not enclosed by a Schwann cell and hence does not form a myelin sheath around the axon.

So the correct option is "Both Assertion and Reason are correct but the reason is not the correct explanation of assertion".

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

The .................... of the neuron secretes the substance named neurotransmitter.

  1. Axon

  2. Dendron

  3. Schwann cell

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The axon of the neuron secretes the substance named neurotransmitter to communicate with next dendrite.

Neurotransmitters are the brain chemicals that communicate information throughout our brain and body.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

The role of the axon is to

  1. Integrate signals from the dendrites

  2. Release neurotransmitter

  3. Conduct the impulse to the synaptic terminal

  4. Synthesize cellular components
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
An axon also known as a nerve fibre, is a long, slender projection of a nerve cell, or neuron, that typically conducts electrical impulses away from the neuron's cell body. The function of the axon is to transmit information to different neurons, muscles and glands. The space between two neuron is known as synapse. The nerve impulse is transmitted towards the synaptic terminal from the dendron.
Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

In comparison with other cells, nerve cells show a higher degree of

  1. Metabolism

  2. Growth

  3. Contractility

  4. Irritability
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Irritability or excitability is the ability of nerve cells to respond to environmental stimulus. Primary function of nerve cells is to generate sensory input in response to external and internal stimuli followed by integration of sensory information to generate motor output. Thus, nerve cells exhibit higher rate of irritability as compared to other cell types. 

Therefore, the correct answer is option D.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Statements (A, B, C, D) in List I have to be matched with statements (p, q, r, s) in List II.

List I List II
A Cyton p  The body of the nerve cell that contains the organelles.
B Dendrite q Receives the stimuli sent from another nerve or the outside environment.
C Axon r A fatty substance that covers the axon of the nerve cell and speeds.
D Myelin sheath s The long, thin section of the nerve cell where the impulse is transmitted across.

  1. A- p, B- q, C- s, D- r

  2. A- r, B- q, C- s, D- p

  3. A- r, B- s, C- q, D- p

  4. A- r, B- s, C- p, D- q
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cyton is the cell body of the neuron. It contains the nucleus.

Dendrites are the cellular extension from the cyton. They receive stimulus, which may be physical, chemical, mechanical or electrical, and pass it on to the cyton.
Axons are also known as nerve fibres which are a projection of a nerve cell, or neuron, that typically conducts electrical impulses away from the neuron's cell body.
Myelin sheath is also known as the medullary sheath. It is the envelope of myelin that surrounds the core of a nerve fiber or axon and that facilitates the transmission of nerve impulses, formed from the cell membrane of the Schwann cell in the peripheral nervous system and from oligodendroglia cells. 
So, the correct answer is option C.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Nerve cells possess
(a) Dendrites
(b) Axon
(c) Sarcolemma
(d) Neurilemma

  1. a, b

  2. a, b, c

  3. a, b, d

  4. a, b, c, d
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Each mammalian neuron consists of a cell body, dendrites, and an axon. The cell body contains the nucleus and cytoplasm. The axon extends from the cell body and often gives rise to many smaller branches before ending at nerve terminals. Dendrites extend from the neuron cell body and receive messages from other neurons. 

The dendrites are covered with synapses formed by the ends of axons from other neurons. 
Neurilemma is the outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron. 
The sarcolemma also called the myolemma, is the cell membrane of a striated muscle fiber cell. It is not present in the nerve cells.

Multiple choice biology plant and animal tissues nervous system in animals structure of neuron structure and function of neuron

Nissl granules are mostly present in 

  1. Axon

  2. Cyton

  3. Dendron

  4. Schwann cells
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A Nissl body is a large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes and are the site of protein synthesis. These are present in cyton of the nerve cell.

So, the correct answer is option B.