Skeletal Muscle Structure — NEET Biology MCQs with Solutions
Free NEET Biology Skeletal Muscle Structure 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 — Skeletal Muscle Structure · easy · theory
The functional (contractile) unit of a skeletal muscle fibre is the:
A. Sarcomere ✓ Correct
B. Myoglobin
C. Sarcolemma
D. Sarcoplasm
Solution: The sarcomere (between two Z lines) is the repeating contractile unit of the myofibril.
Q2 — Skeletal Muscle Structure · easy · theory
The thick filaments of a myofibril are made mainly of the protein:
A. Troponin
B. Actin
C. Tropomyosin
D. Myosin ✓ Correct
Solution: Thick filaments are myosin; thin filaments are actin (with tropomyosin and troponin).
Q3 — Skeletal Muscle Structure · medium · theory
The region of a sarcomere containing only thin filaments, which shrinks during contraction, is the:
A. I band (isotropic, light band) ✓ Correct
B. A band
C. M line
D. H zone only
Solution: The I band (actin only) shortens on contraction; the A band (myosin length) stays constant.
Q4 — Skeletal Muscle Structure · medium · theory
The thin filament of a myofibril is composed of actin plus the regulatory proteins:
A. Myosin and myoglobin
B. Keratin and casein
C. Tropomyosin and troponin ✓ Correct
D. Collagen and elastin
Solution: Each actin (F-actin) filament carries tropomyosin and troponin, which regulate the actin–myosin interaction.
Q5 — Skeletal Muscle Structure · hard · theory
During muscle contraction (sliding filament theory), the ______ shortens while the length of the ______ remains unchanged:
A. A band; I band
B. Sarcomere; myosin filament grows
C. A band; H zone
D. I band and H zone; A band ✓ Correct
Solution: Sliding filament theory: I band and H zone shorten and the sarcomere shortens, but the A band (myosin) length is constant.
Q6 — Skeletal Muscle Structure · hard · theory
The centre of the A band, appearing lighter and lacking thin filaments (at rest), is the:
A. Z line
B. H zone (with the M line at its centre) ✓ Correct
C. I band
D. Sarcolemma
Solution: The H zone is the central A-band region with only thick filaments; the M line bisects it.