Skeletal Muscle Structure — NEET Biology MCQs with Solutions
Free NEET Biology Skeletal Muscle Structure MCQs with step-by-step solutions (57 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.
Q7 — Skeletal Muscle Structure · easy · numerical
A bundle of muscle fibres held together by a common collagenous connective-tissue sheath is called a:
A. Sarcomere
B. Fascicle ✓ Correct
C. Myofibril
D. Sarcomere disc
Solution: Many muscle fibres bundle together into a fascicle wrapped by connective tissue; groups of fascicles form the muscle. A sarcomere and myofibril are sub-cellular contractile units, not bundles of fibres.
Q8 — Skeletal Muscle Structure · easy · numerical
In a muscle fibre the plasma membrane, cytoplasm and endoplasmic reticulum are respectively given the special names:
A. Sarcoplasmic reticulum, sarcolemma and sarcoplasm
B. Sarcolemma, sarcoplasmic reticulum and sarcoplasm
C. Sarcolemma, sarcoplasm and sarcoplasmic reticulum ✓ Correct
D. Sarcoplasm, sarcolemma and sarcoplasmic reticulum
Solution: In muscle, the membrane is the sarcolemma, the cytoplasm is the sarcoplasm, and the endoplasmic reticulum is the sarcoplasmic reticulum, which stores calcium ions.
Q9 — Skeletal Muscle Structure · easy · numerical
The alternating light and dark bands that give skeletal muscle its striated appearance are due to the arrangement of:
A. Nuclei along the sarcolemma
B. Collagen fibres in the perimysium
C. Actin and myosin filaments in the myofibrils ✓ Correct
D. Mitochondria and sarcoplasmic reticulum
Solution: The striations arise from the regular, overlapping arrangement of thin actin and thick myosin filaments; the dark A band and light I band alternate along each myofibril.
Q10 — Skeletal Muscle Structure · easy · numerical
The portion of a myofibril between two successive Z lines represents one:
A. H zone
B. A band
C. I band
D. Sarcomere ✓ Correct
Solution: A sarcomere, the structural and functional unit of the myofibril, is defined as the region between two consecutive Z lines and contains one full A band flanked by half I bands.
Q11 — Skeletal Muscle Structure · medium · numerical
Which set correctly identifies the composition of the thin and thick filaments of a myofibril? Thin — Thick
A. Actin only — myosin and troponin
B. Tropomyosin and myosin — actin and troponin
C. Actin, troponin and tropomyosin — myosin ✓ Correct
D. Myosin — actin and tropomyosin
Solution: The thin filament is built of two F-actin strands plus the regulatory proteins tropomyosin and troponin, whereas the thick filament is composed of myosin (each meromyosin head bearing ATPase activity).
Q12 — Skeletal Muscle Structure · medium · numerical
Assertion (A): In a resting sarcomere the H zone lies in the middle of the A band. Reason (R): The H zone is the central part of the A band where only thick filaments are present and thin filaments do not reach. Choose the correct option.
A. Both A and R are true but R is not the correct explanation of A
B. Both A and R are true and R is the correct explanation of A ✓ Correct
C. A is true but R is false
D. A is false but R is true
Solution: The A band holds the thick filaments; its central region not overlapped by thin filaments is the H zone. Thus the H zone lies mid-A band precisely because thin filaments stop short of it, so R explains A.
Q13 — Skeletal Muscle Structure · medium · numerical
The thin filaments of a sarcomere are anchored and held together at their centre by the:
A. A band boundary
B. Z line (elastic fibre) ✓ Correct
C. H zone
D. M line
Solution: Thin (actin) filaments are held together at the Z line by the elastic protein of the Z line; the M line by contrast holds the thick filaments together at the centre of the A band.
Q14 — Skeletal Muscle Structure · medium · numerical
Which statement comparing red and white muscle fibres is INCORRECT?
A. Red fibres have numerous mitochondria and resist fatigue
B. White fibres have more myoglobin and abundant mitochondria than red fibres ✓ Correct
C. White fibres depend largely on anaerobic metabolism and fatigue quickly
D. Red fibres contain plenty of myoglobin, giving them a reddish colour
Solution: It is the red fibres, not the white, that are rich in myoglobin and mitochondria. White fibres have little myoglobin, fewer mitochondria and rely on anaerobic glycolysis, tiring rapidly.
Q15 — Skeletal Muscle Structure · medium · numerical
The M line of a sarcomere serves to:
A. Mark the region containing only thin filaments
B. Hold the thick (myosin) filaments together at the centre of the A band ✓ Correct
C. Store calcium ions for release during contraction
D. Anchor the thin (actin) filaments at the ends of the sarcomere
Solution: The M line is a proteinaceous line at the centre of the A band that keeps the thick myosin filaments aligned. Thin filaments are anchored at the Z line, and calcium is stored in the sarcoplasmic reticulum.
Q16 — Skeletal Muscle Structure · medium · numerical
Arrange the following in the correct order from largest to smallest structural level of a skeletal muscle: (i) myofibril (ii) muscle fibre (iii) muscle bundle/fascicle (iv) myofilament.
A. (ii) → (i) → (iii) → (iv)
B. (ii) → (iii) → (i) → (iv)
C. (iii) → (ii) → (i) → (iv) ✓ Correct
D. (iii) → (i) → (ii) → (iv)
Solution: A muscle is organised as fascicles (bundles) → muscle fibres (cells) → myofibrils → myofilaments (actin and myosin), progressing from the largest bundle to the smallest filament.
Q17 — Skeletal Muscle Structure · medium · theory
All of the following features are associated with the myosin head of heavy meromyosin (HMM) of muscle protein, except
A. ATPase enzyme activity
B. Myosin binding site ✓ Correct
C. Actin binding site
D. ATP binding site
Solution: The myosin head bears an actin binding site, an ATP binding site and ATPase activity; there is no 'myosin binding site' on it.
Q18 — Skeletal Muscle Structure · medium · theory
Which of the following represents the anatomical unit and structural unit of muscle, respectively?
A. Myofibril; Sarcomere
B. Muscle fibre; Sarcomere ✓ Correct
C. Sarcomere; Muscle fibre
D. Myofibril; Muscle fibre
Solution: The muscle fibre (myofibre) is the anatomical unit, while the sarcomere is the functional/structural unit of contraction.
Q19 — Skeletal Muscle Structure · easy · theory
Sarcolemma is a membrane found over
A. Skeletal muscle fibre ✓ Correct
B. Heart
C. Smooth muscle
D. Nerve fibre
Solution: Sarcolemma is the plasma membrane of a (skeletal) muscle fibre.
Q20 — Skeletal Muscle Structure · easy · theory
The protein which is not a part of thin myofilament is
A. Myosin ✓ Correct
B. Troponin
C. Actin
D. Tropomyosin
Solution: The thin filament is made of actin, troponin and tropomyosin; myosin forms the thick filament.
Q21 — Skeletal Muscle Structure · easy · theory
Ions that are required for formation of cross bridges is
A. Na+
B. Fe2+
C. Ca2+ ✓ Correct
D. K+
Solution: Calcium ions bind troponin, exposing actin sites so myosin cross-bridges can form.
Q22 — Skeletal Muscle Structure · medium · theory
A sarcomere consists of
A. Two A-bands and one I-band
B. One A-band and two half I-bands ✓ Correct
C. One A-band and two I-bands
D. Half A-band and two half I-bands
Solution: A sarcomere (between two Z-lines) has one complete A-band flanked by two half I-bands.
Q23 — Skeletal Muscle Structure · medium · theory
The character which is not associated with white muscle fibres is
A. Depend on anaerobic process for energy
B. Amount of sarcoplasmic reticulum is low ✓ Correct
C. Number of mitochondria are few
D. Less quantity of myoglobin
Solution: White fibres have abundant sarcoplasmic reticulum (not low); they have little myoglobin, few mitochondria and rely on anaerobic metabolism.
Q24 — Skeletal Muscle Structure · easy · theory
Motor neuron along with muscle fibres are connected and constitute a
A. Neuromuscular junction
B. Sarcomere
C. Motor unit ✓ Correct
D. Motor end plate
Solution: A motor neuron together with the muscle fibres it innervates forms a motor unit.
Q25 — Skeletal Muscle Structure · medium · theory
The muscle band which remains unchanged during contraction and relaxation of skeletal muscle is
A. I-band
B. Z-line
C. A-band ✓ Correct
D. H-zone
Solution: The A-band (length of thick filaments) stays constant; the I-band and H-zone shorten during contraction.
Q26 — Skeletal Muscle Structure · easy · theory
Which one has oxygen storing capacity?
A. Actin
B. Myoglobin ✓ Correct
C. Fibrin
D. Myosin
Solution: Myoglobin is the oxygen-storing pigment of muscle.
Q27 — Skeletal Muscle Structure · easy · theory
Smallest muscle in the human body is
A. Sartorius
B. Stapedius ✓ Correct
C. Gluteus maximus
D. Spinal muscle
Solution: The stapedius is the smallest skeletal muscle in the human body.
Q28 — Skeletal Muscle Structure · easy · theory
End plate junction is present between
A. Neuron and striated muscle ✓ Correct
B. Neuron and gland
C. Neuron and neuron
D. Muscle and muscle
Solution: The motor end plate (neuromuscular junction) lies between a motor neuron and a striated muscle fibre.
Q29 — Skeletal Muscle Structure · medium · theory
In a resting muscle fibre, troponin partially covers
A. Actin binding sites on myosin
B. Ca-binding sites on actin
C. Ca-binding sites on troponin
D. Myosin binding sites on actin ✓ Correct
Solution: At rest, the troponin-tropomyosin complex masks the myosin (active) binding sites on actin.
Q30 — Skeletal Muscle Structure · medium · theory
Cross bridges between actin and myosin is broken up by
A. Binding of ATP to the myosin head ✓ Correct
B. Binding of calcium to the subunit of troponin
C. Exposure of tropomyosin
D. Hydrolysis of ATP
Solution: A fresh ATP molecule binding to the myosin head releases it from actin, breaking the cross-bridge.