Part 4: Muscle Twitch and Fatigue – Types of Muscles, Rigor Mortis, Differences
Part 4 (25 MCQs) on Muscle Twitch and Fatigue – Types of Muscles, Rigor Mortis, Differences from Chapter 20: Locomotion and Movement (NCERT Class 11 + NEET UG level).
Part 4: Muscle Twitch and Fatigue – Types of Muscles, Rigor Mortis, Differences
Q1. A single short contraction and relaxation of a muscle fiber is called:
a) Muscle fatigue
b) Muscle twitch
c) Tetanus
d) Rigor mortis
Answer: b) Muscle twitch
Explanation:
- ✅ (b) A twitch = brief contraction + relaxation after a single stimulus.
- (a) Fatigue = reduced efficiency.
- (c) Tetanus = sustained contraction.
- (d) Rigor mortis = post-mortem stiffness.
Q2. A typical muscle twitch has three phases:
a) Contraction, relaxation, fatigue
b) Latent period, contraction, relaxation
c) Latent, fatigue, rigor
d) Rest, contraction, fatigue
Answer: b) Latent period, contraction, relaxation
Explanation:
- ✅ (b) Muscle twitch = latent period → contraction → relaxation.
Q3. Muscle fatigue is mainly caused by accumulation of:
a) Lactic acid
b) Urea
c) Carbon dioxide
d) Ammonia
Answer: a) Lactic acid
Explanation:
- ✅ (a) Anaerobic glycolysis → lactic acid → fatigue.
Q4. Rigor mortis sets in after death due to:
a) Accumulation of lactic acid
b) Depletion of ATP
c) Excess oxygen
d) Loss of calcium
Answer: b) Depletion of ATP
Explanation:
- ✅ (b) No ATP → actin-myosin remain bound → stiffness.
Q5. Which type of muscle is multinucleated and voluntary?
a) Cardiac muscle
b) Skeletal muscle
c) Smooth muscle
d) None
Answer: b) Skeletal muscle
Explanation:
- ✅ (b) Skeletal muscles = striated, multinucleated, voluntary.
Q6. Which muscle is striated but involuntary?
a) Skeletal muscle
b) Cardiac muscle
c) Smooth muscle
d) Intestinal muscle
Answer: b) Cardiac muscle
Explanation:
- ✅ (b) Cardiac → striated, branched, involuntary.
Q7. Smooth muscles are:
a) Striated and voluntary
b) Non-striated and involuntary
c) Striated and involuntary
d) Non-striated and voluntary
Answer: b) Non-striated and involuntary
Explanation:
- ✅ (b) Smooth muscles = spindle-shaped, involuntary.
Q8. Which muscles are fatigue-resistant?
a) Skeletal muscles
b) Smooth muscles
c) Cardiac muscles
d) Both b and c
Answer: d) Both b and c
Explanation:
- ✅ (d) Smooth & cardiac muscles rarely fatigue.
Q9. In muscle fatigue, muscle is unable to contract due to:
a) Lack of Ca²⁺
b) Lack of ATP
c) Lack of oxygen
d) Accumulation of lactic acid
Answer: d) Accumulation of lactic acid
Explanation:
- ✅ (d) Acidic environment interferes with contraction.
Q10. Which period in muscle twitch is the shortest?
a) Latent period
b) Contraction period
c) Relaxation period
d) Fatigue
Answer: a) Latent period
Explanation:
- ✅ (a) Latent = milliseconds, shortest phase.
Q11. Cardiac muscle fibers are connected by:
a) Sarcolemma
b) Intercalated discs
c) Gap junctions only
d) T-tubules
Answer: b) Intercalated discs
Explanation:
- ✅ (b) Intercalated discs allow electrical coupling.
Q12. Skeletal muscle fatigue is temporary and can be removed by:
a) Rest
b) Death
c) ATP depletion
d) Oxygen absence
Answer: a) Rest
Explanation:
- ✅ (a) Rest removes lactic acid → muscle recovers.
Q13. The main source of energy during prolonged muscle activity is:
a) Creatine phosphate
b) Glycogen
c) Glucose
d) ATP
Answer: b) Glycogen
Explanation:
- ✅ (b) Glycogen stores → main fuel for prolonged activity.
Q14. Rigor mortis usually sets in:
a) Immediately after death
b) 1–2 hours after death
c) 1–2 days after death
d) Only in old age
Answer: b) 1–2 hours after death
Explanation:
- ✅ (b) Rigor mortis sets ~1–2 hrs, lasts up to 24 hrs.
Q15. Which muscle shows myogenic contraction?
a) Skeletal
b) Cardiac
c) Smooth
d) Both b and c
Answer: d) Both b and c
Explanation:
- ✅ (d) Cardiac & smooth muscles contract spontaneously (myogenic).
Q16. The refractory period in cardiac muscle is:
a) Very short
b) Very long
c) Absent
d) Same as skeletal muscle
Answer: b) Very long
Explanation:
- ✅ (b) Long refractory period prevents tetany in cardiac muscle.
Q17. Which muscle type has sarcomeres?
a) Skeletal and cardiac
b) Smooth only
c) All three types
d) None
Answer: a) Skeletal and cardiac
Explanation:
- ✅ (a) Sarcomeres = striated arrangement (skeletal & cardiac).
Q18. Which muscle shows voluntary control?
a) Skeletal
b) Smooth
c) Cardiac
d) None
Answer: a) Skeletal
Explanation:
- ✅ (a) Skeletal = voluntary, under somatic control.
Q19. Smooth muscle contraction is regulated by:
a) Troponin
b) Tropomyosin
c) Calmodulin
d) Myoglobin
Answer: c) Calmodulin
Explanation:
- ✅ (c) Calmodulin (instead of troponin) regulates contraction in smooth muscles.
Q20. Which muscle is branched and cylindrical?
a) Skeletal
b) Cardiac
c) Smooth
d) Both a and b
Answer: b) Cardiac
Explanation:
- ✅ (b) Cardiac muscles = branched, striated, involuntary.
Q21. The difference between skeletal and cardiac muscle is:
a) Both are voluntary
b) Both are involuntary
c) Skeletal voluntary, cardiac involuntary
d) Skeletal involuntary, cardiac voluntary
Answer: c) Skeletal voluntary, cardiac involuntary
Explanation:
- ✅ Correct difference.
Q22. Muscle fatigue is an example of:
a) Inflammation
b) Reversible physiological state
c) Genetic disorder
d) Degenerative disease
Answer: b) Reversible physiological state
Explanation:
- ✅ (b) Fatigue reverses after rest.
Q23. Which type of muscle fibers are more abundant in marathon runners?
a) Fast-twitch
b) Slow-twitch (red fibers)
c) White fibers
d) None
Answer: b) Slow-twitch (red fibers)
Explanation:
- ✅ (b) Red fibers (myoglobin-rich) resist fatigue, suited for endurance.
Q24. In rigor mortis, cross-bridges remain because:
a) ATP hydrolysis continues
b) ATP is absent
c) Excess Ca²⁺ prevents detachment
d) Myoglobin deficiency
Answer: b) ATP is absent
Explanation:
- ✅ (b) ATP required for myosin detachment; absence = stiffness.
Q25. Which muscle disorder is due to immune attack on acetylcholine receptors?
a) Muscular dystrophy
b) Myasthenia gravis
c) Tetany
d) Rigor mortis
Answer: b) Myasthenia gravis
Explanation:
- ✅ (b) Autoimmune disease → weak, fatigued muscles.
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