Tag: biology

Quizzes (1160) Questions (12174)

Questions Related to biology

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

Primary function of myelin sheath around vertebrate axon is to

  1. Regulate Na-K pump

  2. Increase in size of action potential

  3. Increase in speed of conduction by preventing leakage of nerve impulse

  4. Deactivate the release of neurotransmitter
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The myelin sheath acts as an electrical insulator, preventing ion leakage and allowing saltatory conduction, which significantly increases the speed of nerve impulse transmission.

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

Characteristics of graded potential is

  1. Always followed by a refractory period

  2. Amplitude is always the same

  3. Duration and strength varies

  4. All or none response
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Unlike action potentials, which are 'all-or-none', graded potentials vary in amplitude and duration depending on the strength of the stimulus.