Mechanism of Muscle Contraction — NEET Biology MCQs with Solutions
Free NEET Biology Mechanism of Muscle Contraction MCQs with step-by-step solutions (6 questions). Part of Locomotion and Movement. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Mechanism of Muscle Contraction · easy · theory
The ion whose release from the sarcoplasmic reticulum triggers muscle contraction is:
A. Calcium (Ca²⁺) ✓ Correct
B. Sodium (Na⁺)
C. Potassium (K⁺)
D. Chloride (Cl⁻)
Solution: A nerve impulse causes Ca²⁺ release, which initiates the contraction cycle by exposing actin binding sites.
Q2 — Mechanism of Muscle Contraction · easy · theory
The neurotransmitter released at the neuromuscular junction to stimulate a muscle fibre is:
A. Insulin
B. Acetylcholine ✓ Correct
C. Adrenaline
D. Dopamine
Solution: Acetylcholine released at the motor end-plate depolarises the sarcolemma, initiating contraction.
Q3 — Mechanism of Muscle Contraction · medium · theory
Ca²⁺ initiates contraction by binding to ______, which moves ______ to expose the myosin-binding sites on actin:
A. Tropomyosin; troponin
B. Actin; myoglobin
C. Troponin; tropomyosin ✓ Correct
D. Myosin; actin
Solution: Ca²⁺ binds troponin, shifting tropomyosin away from actin's binding sites so cross-bridges can form.
Q4 — Mechanism of Muscle Contraction · medium · theory
The energy for the sliding of filaments (breaking of the actin-myosin cross-bridge) comes from:
A. Hydrolysis of ATP ✓ Correct
B. Lactic acid
C. Ca²⁺ binding alone
D. Oxygen alone
Solution: ATP binds the myosin head to release it from actin; its hydrolysis re-cocks the head for the next stroke.
Q5 — Mechanism of Muscle Contraction · hard · theory
The reddish muscle fibres that resist fatigue contain abundant ______ and rely on ______ respiration:
A. Actin only; anaerobic
B. Glycogen only; anaerobic
C. Myoglobin/mitochondria; aerobic ✓ Correct
D. Calcium; fermentation
Solution: Red (type I) fibres have plentiful myoglobin and mitochondria, favouring aerobic respiration and endurance.
Q6 — Mechanism of Muscle Contraction · hard · theory
The rigor mortis (stiffening of muscles after death) occurs because:
A. Muscles keep contracting with energy
B. ATP is no longer available to detach the myosin heads from actin ✓ Correct
C. Calcium is completely removed
D. Too much ATP is present
Solution: Without ATP, cross-bridges cannot detach, so actin and myosin remain locked — causing rigor mortis.