Biology

Nervous System and Neurons

1,224 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

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.

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


In the resting state, the axonal membrane is (i)_ with more (ii) charged ions outside than inside. This unequal distribution of ions is due to (1) the selective permeability of the membrane, which forms an almost impenetrable barrier to (iii) and (2) the action of the _(iv), which pumps (v) Na$^+$ out of the neuron for every _(vi) K$^+$ brought in.
Select the option that correctly fills the blanks in the paragraph.

  1. (i) - depolarised, (ii) - positively, (iii) - Na$^+$, (iv) - sodium - potassium pump, (v) - three, (vi) - two
  2. (i) - depolarised, (ii) - negatively, (iii) - Na$^+$, (iv) - sodium - potassium pump, (v) - three, (vi) - two
  3. (i) - polarised, (ii) - negatively, (iii) - Na$^+$, (iv) - sodium - potassium pump, (v) - three, (vi) - two
  4. (i) - polarised, (ii) - positively, (iii) - Na$^+$, (iv) - sodium - potassium pump, (v) - three, (vi) - two
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the resting state, the axonal membrane is polarised with more positively charged ions outside than inside, unequal distribution of ions is due to the selective permeability of the membrane, which forms impermeable barrier to sodium ion and the action of the sodium which pumps three sodium ions out of the neuron for every two potassium ions brought in.

Thus, the correct option is '(i) - polarised, (ii) - positively, (iii) - Na$^+$, (iv) - sodium - potassium pump, (v) - three, (vi) - two.'

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

Sodium potassium pump transports

  1. Na+ and K+ out of the neuron

  2. Na+ and K+ into the neuron

  3. Na+ into the neuron and K+ out of the neuron

  4. K+ into the neuron and Na+ out of the neuron
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The sodium-potassium pump actively transports 3 Na+ ions out of the neuron and 2 K+ ions into the neuron, maintaining the electrochemical gradient.