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 coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

Depolarisation of nerve cell involves

  1. Influx of $K^+$
  2. Influx of N$a^+$
  3. Influx of C$a^{2+}$ and Cl
  4. Efflux of N$a^{2+}$
  5. Efflux of C$a^{2+}$ and Cl
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Depolarization occurs when the resting membrane potential becomes less negative. This is primarily caused by the rapid opening of voltage-gated sodium channels, allowing Na+ to rush into the cell.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

In resting stage of neuron, diffusion due to concentration gradient will drive

  1. $K^+$ into cell
  2. $K^+$and N$a^+$ out of cell
  3. N$a^+$ into cell
  4. N$a^+$ out of cell
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the resting state, there is a high concentration of Na+ outside the cell and a low concentration inside. Due to the concentration gradient, Na+ ions have a natural tendency to diffuse into the cell, though the membrane is relatively impermeable to them at rest.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

At resting stage nerve cell has

  1. Low $K^+$ outside and high N$a^+$ inside
  2. High $K^+$ inside and high N$a^+$ outside
  3. High $K^+$ inside and low N$a^+$ outside
  4. High $K^+$ outside and low N$a^+$ inside
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

At resting stage, the Na-K pump maintains a high concentration of K+ inside the neuron and a high concentration of Na+ outside the neuron.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

A polarised neuron is the one that is

  1. Conducting stimulus

  2. At resting potential

  3. Having action potential

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

A polarized neuron is one that is at its resting potential, meaning there is a stable difference in electrical charge across the membrane (negative inside, positive outside).

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

During conduction of nerve impulse

  1. N$a^+$ moves out of axoplasm
  2. N$a^+$ moves into axoplasm
  3. $K^+$ moves into axoplasm
  4. C$a^{2+}$ moves into axoplasm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During the depolarization phase of a nerve impulse, voltage-gated sodium channels open, allowing Na+ to move down its concentration gradient into the axoplasm.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

The processes that occur during repolarisation of nerve fibres are 
(i) Open N$a^+$ channels 
(ii) Closed N$a^+$ channels 
(iii) Closed $K^+$ channels 
(iv) Open $K^+$ channels

  1. (ii) and (iii)

  2. (i) and (ii)

  3. (ii) and (iv)

  4. (i) and (iii)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Repolarization occurs when sodium channels close and potassium channels open, allowing K+ to flow out of the cell to restore the negative resting potential.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

Choose the correct statements

  1. Nonmyelinated nerve fibres are found in spinal and cranial nerves

  2. Retina has multipolar neurons

  3. Electrical synapses are commonly present in humans

  4. Impulse transmission across an electrical synapse is faster than across a chemical synapse

  5. In resting neuron, axoplasm inside the axon contains high concentration of sodium ion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electrical synapses allow for direct ion flow between neurons via gap junctions, making transmission significantly faster than the chemical process of releasing and binding neurotransmitters.

Multiple choice biology coordination generation and conduction of nerve impulse generation of nerve impulse neurons and synapses

Which is wrong regarding conduction of nerve impulse

  1. In a resting neuron, the axonal membrane is more permeable to $K^+$ ions and nearly impermeable to N$a^+$ ions
  2. Fluid outside the axon has a high concentration of N$a^+$ and low concentration of $K^+$, in a resting neuron

  3. Resting potential is the electrical potential difference across the resting membrane

  4. A neuron is polarised only when the outer surface of axonal membrane possesses a negative charge and inner surface is positively charged
  5. Ionic gradients are maintained by Na-K pumps across the resting membrane which transports 3 N$a^+$ ions outwards for 2$K^+$ ions into the cell
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A polarized neuron has a positive charge on the outer surface and a negative charge on the inner surface. Option D incorrectly states the reverse.