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IB Biology HL B3.3.4 Hl Motor Units Questions

Explore how amino-acid R-group chemistry changes solubility, interactions, folding and protein function in IB Biology HL B1.2.6.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Identify a motor unit as a motor neuron and the skeletal muscle fibres it controls, joined at neuromuscular junctions.
  • Explain that acetylcholine released at the motor end plate after a motor-neuron action potential excites the muscle-fibre sarcolemma.
  • Trace excitation from the motor end plate to calcium-ion release from the sarcoplasmic reticulum, initiating skeletal-muscle contraction.

IB Biology HL B3.3.4 Hl Motor Units Questions question 1

[Maximum number: 1]

What happens when an action potential reaches motor end plates?

A

Calcium ions are absorbed by the muscle fibres.

B

The sarcomeres relax.

C

Neurotransmitter is released.

D

Action potential is passed to the neuron.

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