Structure of contractile proteins, Mechanism of muscle contraction — NEET Biology Questions

Practice 30 questions on Structure of contractile proteins, Mechanism of muscle contraction from Locomotion and movement (NCERT Class 11, Chapter 17). Free samples below — get all 30 in the app.

30 Questions Locomotion and movement Class 11

Sample Questions — Structure of contractile proteins, Mechanism of muscle contraction

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MCQ
Cross-bridge cycling is driven by:
  • A. Troponin breakdown
  • B. Tropomyosin elongation
  • C. ATP hydrolysis by myosin head
  • D. Actin polymerisation
✅ Correct Answer: C
Energy from ATP hydrolysis fuels the formation and breakage of cross-bridges.
MCQ
5. What is the mechanism behind muscle contraction?
  • A. Folding of actin filaments
  • B. Cross-linking of actin and troponin
  • C. Sliding of thin filaments over thick filaments
  • D. Relaxation of sarcolemma
✅ Correct Answer: C
Sliding filament theory explains contraction by thin filament sliding over thick.
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MCQ
Why are red muscle fibres more fatigue-resistant than white fibres?
  • A. Due to less mitochondria
  • B. Because they have more myoglobin and mitochondria
  • C. Because they rely on anaerobic metabolism
  • D. They store more Ca²⁺
✅ Correct Answer: B
Red fibres contain more myoglobin and mitochondria, supporting aerobic respiration and fatigue resistance.
MCQ
Why does the head of myosin project outward in a regular pattern?
  • A. To stabilize the sarcomere
  • B. To allow ATP storage
  • C. To form cross-bridges with actin
  • D. To attach to tropomyosin
✅ Correct Answer: C
The head and short arm of HMM (myosin) project outward and help form cross-bridges with actin filaments.
MCQ
10. What causes muscle relaxation after contraction?
  • A. Release of ATP
  • B. Masking of actin sites
  • C. Ca²⁺ increase
  • D. Troponin inhibition
✅ Correct Answer: B
Reabsorption of Ca²⁺ causes re-masking of actin and muscle relaxation.

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