Chapter 20: Locomotion and Movement – MCQs
Locomotion & Movement – MCQs
Part 1 (Q1–Q25)
Q1. The basic functional unit of skeletal muscle is the:
a) Myofibril
b) Sarcomere
c) Motor unit
d) Fascicle
Answer: b) Sarcomere
- a) Myofibril — a structure composed of repeating sarcomeres; not the smallest functional contractile unit.
- b) Sarcomere — correct; sarcomeres (between Z-discs) are the contractile units where actin–myosin interactions occur.
- c) Motor unit — a motor neuron + the muscle fibres it innervates; functional for control, not the microscopic contractile unit.
- d) Fascicle — a bundle of muscle fibers; larger structural unit.
Q2. During muscle contraction, which filament slides past the other according to the sliding-filament theory?
a) Actin slides past myosin
b) Myosin slides past actin
c) Both actin and myosin shorten
d) Neither filament moves—sarcomere shortens by other means
Answer: a) Actin slides past myosin
- a) Actin slides past myosin — correct phrasing: thin (actin) filaments are pulled inward by myosin cross-bridges, producing shortening.
- b) Myosin slides past actin — equivalent idea but conventional description is actin sliding toward center; myosin heads pull actin. (Less preferred wording.)
- c) Both shorten — incorrect; filaments themselves do not shorten, overlap increases.
- d) Neither moves — incorrect; relative sliding of filaments shortens sarcomere.
Q3. Which ion released from the sarcoplasmic reticulum initiates muscle contraction?
a) Sodium (Na⁺)
b) Potassium (K⁺)
c) Calcium (Ca²⁺)
d) Magnesium (Mg²⁺)
Answer: c) Calcium (Ca²⁺)
- a) Na⁺ — important for action potential propagation, not direct trigger of contraction.
- b) K⁺ — involved in repolarization, not trigger.
- c) Ca²⁺ — correct; Ca²⁺ binds troponin, shifting tropomyosin to expose actin binding sites.
- d) Mg²⁺ — cofactor in ATPases but not primary trigger.
Q4. The molecule that directly provides energy for the myosin head power stroke is:
a) ATP
b) ADP
c) Creatine phosphate
d) Glucose
Answer: a) ATP
- a) ATP — correct; ATP binding and hydrolysis on myosin drive cross-bridge cycling and power stroke.
- b) ADP — product of ATP hydrolysis; remains bound transiently but is not the direct energy source to start the next cycle.
- c) Creatine phosphate — rapid source to regenerate ATP (via creatine kinase), but not the direct substrate used by myosin.
- d) Glucose — metabolic fuel upstream in pathways that produce ATP.
Q5. Which protein blocks the myosin-binding site on actin in a relaxed muscle?
a) Troponin
b) Tropomyosin
c) Titin
d) Nebulin
Answer: b) Tropomyosin
- a) Troponin — regulatory complex that senses Ca²⁺ and moves tropomyosin, but it does not physically block the site.
- b) Tropomyosin — correct; lies in the groove of actin filament and covers myosin-binding sites when Ca²⁺ is low.
- c) Titin — elastic protein that maintains sarcomere structure.
- d) Nebulin — structural protein associated with thin filament length regulation.
Q6. The neuromuscular junction neurotransmitter responsible for skeletal muscle excitation is:
a) Norepinephrine
b) Acetylcholine
c) Dopamine
d) GABA
Answer: b) Acetylcholine
- a) Norepinephrine — sympathetic neurotransmitter, not used at skeletal NMJ.
- b) Acetylcholine — correct; released from motor neuron terminals, binds nicotinic receptors on muscle endplate.
- c) Dopamine — CNS neurotransmitter; not NMJ transmitter.
- d) GABA — inhibitory CNS transmitter, not skeletal NMJ.
Q7. Which of the following best describes a motor unit?
a) A single muscle fibre
b) A single motor neuron and all the muscle fibres it innervates
c) A group of motor neurons working together
d) A sarcomere plus neuromuscular junction
Answer: b) A single motor neuron and all the muscle fibres it innervates
- a) Single muscle fibre — component of a motor unit, but incomplete definition.
- b) Motor neuron + its fibres — correct; basis for graded force via recruitment.
- c) Group of motor neurons — not a motor unit.
- d) Sarcomere + NMJ — incorrect composition.
Q8. Which muscle fiber type has high myoglobin content, many mitochondria, and is fatigue-resistant?
a) Type I (slow oxidative)
b) Type IIa (fast oxidative-glycolytic)
c) Type IIb/IIx (fast glycolytic)
d) Cardiac muscle fibres
Answer: a) Type I (slow oxidative)
- a) Type I — correct; slow-twitch, rich in myoglobin & mitochondria — suited for endurance.
- b) Type IIa — intermediate: faster but reasonably oxidative.
- c) Type IIb/IIx — fast, glycolytic, fatigue quickly.
- d) Cardiac fibres — similar oxidative properties but different physiology & regulation.
Q9. Rigor mortis (stiffening after death) occurs because:
a) Excess ATP causes sustained contraction
b) Lack of ATP prevents myosin from detaching from actin
c) Ca²⁺ levels fall to zero preventing contraction
d) Troponin degrades immediately after death
Answer: b) Lack of ATP prevents myosin detachment from actin
- a) Excess ATP — opposite; ATP shortage is key.
- b) Lack of ATP — correct; without ATP myosin heads cannot release actin, causing stiff muscles.
- c) Ca²⁺ fall — cytosolic Ca²⁺ may rise post-mortem due to pump failure; but ATP lack is primary.
- d) Troponin degradation — not immediate cause of rigor mortis.
Q10. In an isometric muscle contraction:
a) Muscle length changes but tension remains constant
b) Muscle shortens while tension increases
c) Muscle length remains constant while tension increases
d) Muscle neither changes length nor tension
Answer: c) Muscle length remains constant while tension increases
- a) Length changes — describes isotonic contraction, not isometric.
- b) Shortens — isotonic concentric contraction.
- c) Length constant, tension rises — correct; e.g., holding a heavy object stationary.
- d) Neither changes — not a physiological contractile state.
Q11. Which enzyme regenerates ATP rapidly in muscle using creatine phosphate?
a) Creatine kinase
b) ATP synthase
c) Phosphofructokinase
d) Lactate dehydrogenase
Answer: a) Creatine kinase
- a) Creatine kinase — correct; transfers phosphate from creatine phosphate to ADP → ATP.
- b) ATP synthase — mitochondrial oxidative phosphorylation enzyme, slower.
- c) PFK — glycolysis regulatory enzyme.
- d) LDH — converts pyruvate ↔ lactate, not direct ATP regeneration from creatine phosphate.
Q12. Which type of joint permits the greatest range of movement (e.g., shoulder, hip)?
a) Hinge joint
b) Pivot joint
c) Ball-and-socket joint
d) Saddle joint
Answer: c) Ball-and-socket joint
- a) Hinge — allows flexion/extension (elbow), limited plane.
- b) Pivot — rotation around axis (atlantoaxial).
- c) Ball-and-socket — correct; multiaxial movement (flexion/extension, ab/adduction, rotation).
- d) Saddle — biaxial (thumb CMC joint).
Q13. Osteoclasts are involved in:
a) Bone formation (osteogenesis)
b) Bone resorption (breaking down bone)
c) Cartilage synthesis
d) Producing bone matrix proteins only
Answer: b) Bone resorption (breaking down bone)
- a) Bone formation — done by osteoblasts.
- b) Bone resorption — correct; osteoclasts digest bone matrix, important in remodeling and calcium homeostasis.
- c) Cartilage synthesis — chondrocytes do this.
- d) Bone matrix proteins — osteoblasts secrete these.
Q14. Which hormone increases bone resorption to raise blood Ca²⁺?
a) Calcitonin
b) Parathyroid hormone (PTH)
c) Insulin
d) Growth hormone
Answer: b) Parathyroid hormone (PTH)
- a) Calcitonin — lowers blood Ca²⁺ by inhibiting osteoclasts (opposite effect).
- b) PTH — correct; increases osteoclast activity indirectly, promotes Ca²⁺ release from bone.
- c) Insulin — anabolic effects, not direct bone resorbing hormone.
- d) GH — stimulates growth, but not primary acute Ca²⁺ regulator.
Q15. Myasthenia gravis is caused by:
a) Destruction of muscle fibers by bacteria
b) Autoimmune antibodies against postsynaptic acetylcholine receptors at NMJ
c) Genetic absence of myosin
d) Excess acetylcholine release from motor neurons
Answer: b) Autoimmune antibodies against postsynaptic ACh receptors
- a) Bacterial destruction — not the cause.
- b) Autoimmune AChR antibodies — correct; cause decreased receptor availability → fatigable weakness.
- c) Genetic myosin absence — not MG.
- d) Excess ACh release — would increase activation, not typical MG.
Q16. Which statement about smooth muscle is TRUE?
a) It has sarcomeres with striations like skeletal muscle
b) Contraction is primarily under voluntary control
c) It lacks troponin and uses calmodulin–myosin light chain kinase pathway
d) It always contracts faster than skeletal muscle
Answer: c) Lacks troponin; uses calmodulin–MLCK pathway
- a) Has sarcomeres — false; smooth muscle is non-striated.
- b) Voluntary control — false; largely involuntary under autonomic control.
- c) Calmodulin/MLCK mechanism — correct; Ca²⁺ binds calmodulin, activates MLCK, phosphorylates myosin light chain.
- d) Always faster — false; smooth muscle contractions are generally slower.
Q17. A concentric isotonic contraction is when:
a) Muscle lengthens while generating force
b) Muscle shortens while generating force
c) Muscle length remains constant while force changes
d) Muscle relaxes completely
Answer: b) Muscle shortens while generating force
- a) Lengthens under load — eccentric contraction.
- b) Shortens — correct; e.g., lifting a weight.
- c) Isometric — length constant.
- d) Relaxation — not contraction.
Q18. Which structure transmits action potentials deep into a skeletal muscle fibre to trigger Ca²⁺ release?
a) Sarcolemma only
b) Transverse (T) tubules
c) Mitochondria
d) Golgi tendon organ
Answer: b) Transverse (T) tubules
- a) Sarcolemma conducts AP on surface, but deep transmission uses T-tubules.
- b) T tubules — correct; invaginations of sarcolemma that carry APs to SR.
- c) Mitochondria — energy producers, not AP conduits.
- d) Golgi tendon organ — proprioceptor sensing tension.
Q19. Which sensory receptor detects muscle stretch and mediates the stretch (myotatic) reflex?
a) Pacinian corpuscle
b) Golgi tendon organ
c) Muscle spindle (stretch receptor)
d) Ruffini ending
Answer: c) Muscle spindle (stretch receptor)
- a) Pacinian — vibration/pressure receptor.
- b) Golgi tendon — senses tension, mediates inverse myotatic reflex (inhibits contraction).
- c) Muscle spindle — correct; detects stretch and triggers reflex contraction.
- d) Ruffini — skin stretch receptor.
Q20. Which statement about antagonistic muscle pairs is correct?
a) Both muscles contract simultaneously to produce movement
b) One muscle contracts while the antagonist relaxes to allow movement
c) Antagonists are inactive muscles with no function
d) Antagonists refer to muscles in the same tendon only
Answer: b) One contracts while antagonist relaxes
- a) Both contract — would prevent movement or cause rigidity.
- b) Agonist contracts, antagonist relaxes — correct; e.g., biceps (flexor) contracts while triceps (extensor) relaxes.
- c) Inactive — incorrect, antagonists control and modulate movement.
- d) Same tendon — irrelevant.
Q21. Tetanic contraction (tetanus) of a muscle occurs when:
a) Individual twitches are separated by long relaxation periods
b) Stimuli are delivered at high frequency so twitches fuse into sustained contraction
c) No ATP is available
d) Muscle is fully relaxed
Answer: b) High-frequency stimuli produce fused contraction
- a) Long relaxation — produces separate twitches, not tetanus.
- b) High-frequency stimulation — correct; temporal summation produces sustained tetanus.
- c) No ATP — would cause rigor rather than tetanus.
- d) Relaxed — not tetanus.
Q22. Which disease is caused by a toxin that prevents inhibitory neurotransmitter release leading to spastic paralysis (lockjaw)?
a) Botulism
b) Tetanus
c) Myasthenia gravis
d) Muscular dystrophy
Answer: b) Tetanus
- a) Botulism — toxin blocks ACh release at NMJ causing flaccid paralysis.
- b) Tetanus — correct; tetanospasmin inhibits inhibitory interneurons (GABA/glycine) → uncontrolled muscle contraction.
- c) Myasthenia — autoimmune against ACh receptors causing fatigable weakness.
- d) Muscular dystrophy — genetic muscle degeneration.
Q23. Which process predominates for ATP production during prolonged endurance exercise?
a) Creatine phosphate breakdown
b) Anaerobic glycolysis only
c) Oxidative phosphorylation (aerobic metabolism) in mitochondria
d) Direct ATP absorption from blood
Answer: c) Oxidative phosphorylation (aerobic)
- a) Creatine phosphate — supplies ATP for seconds, not prolonged exercise.
- b) Anaerobic glycolysis — important for short, high-intensity bursts; accumulates lactate.
- c) Oxidative phosphorylation — correct; sustained ATP generation using carbs & fats in mitochondria.
- d) Direct ATP absorption — not a physiological source.
Q24. Duchenne muscular dystrophy is primarily due to:
a) Autoimmune destruction of NMJ
b) Mutation in dystrophin gene leading to progressive muscle degeneration
c) Lack of acetylcholine production
d) Excessive PTH activity
Answer: b) Mutation in dystrophin gene
- a) Autoimmune — describes myasthenia gravis, not DMD.
- b) Dystrophin mutation — correct; X-linked recessive disease causing muscle fiber breakdown.
- c) Lack ACh — not DMD.
- d) PTH — endocrine, unrelated.
Q25. Which connective tissue layer surrounds an individual skeletal muscle fibre?
a) Epimysium
b) Perimysium
c) Endomysium
d) Fascia lata
Answer: c) Endomysium
- a) Epimysium — surrounds entire muscle (many fascicles).
- b) Perimysium — surrounds fascicles (bundles of fibres).
- c) Endomysium — correct; thin connective tissue surrounding each muscle fiber.
- d) Fascia lata — deep fascia of the thigh, not the general microscopic layer.
Part 2: Human Physiology – Locomotion and Movement (Q26–Q50)
Q26. Which ion plays the most important role in muscle contraction?
a) Sodium
b) Potassium
c) Calcium
d) Chloride
Answer: c) Calcium
Explanation: Calcium ions bind to troponin, displacing tropomyosin, thereby exposing myosin-binding sites on actin filaments and initiating contraction.
Q27. Which part of the sarcomere shortens during muscle contraction?
a) A band
b) I band
c) H zone
d) Z line
Answer: c) H zone
Explanation: The H zone shortens or disappears during contraction because the actin filaments slide toward the center of the sarcomere.
Q28. The functional unit of a muscle is called:
a) Sarcolemma
b) Myofibril
c) Sarcomere
d) Sarcoplasm
Answer: c) Sarcomere
Explanation: The sarcomere is the structural and functional unit of a myofibril, bounded by Z lines.
Q29. Which muscle type is involuntary and striated?
a) Skeletal
b) Smooth
c) Cardiac
d) Voluntary
Answer: c) Cardiac
Explanation: Cardiac muscles are striated like skeletal muscles but involuntary in action.
Q30. Which connective tissue sheath surrounds each muscle fiber?
a) Endomysium
b) Perimysium
c) Epimysium
d) Fascia
Answer: a) Endomysium
Explanation: Endomysium is the connective tissue covering an individual muscle fiber.
Q31. Which joint allows movement in all directions?
a) Hinge joint
b) Pivot joint
c) Ball and socket joint
d) Gliding joint
Answer: c) Ball and socket joint
Explanation: Ball and socket joints (e.g., hip and shoulder) allow movement in all planes.
Q32. What is the neurotransmitter involved in muscle contraction?
a) Dopamine
b) Serotonin
c) Acetylcholine
d) Adrenaline
Answer: c) Acetylcholine
Explanation: Acetylcholine is released at the neuromuscular junction to stimulate muscle contraction.
Q33. The knee joint is an example of:
a) Ball and socket joint
b) Hinge joint
c) Pivot joint
d) Saddle joint
Answer: b) Hinge joint
Explanation: The knee joint allows movement similar to a door hinge – flexion and extension.
Q34. Which filament is composed of myosin?
a) Thick filament
b) Thin filament
c) Z line
d) Tropomyosin
Answer: a) Thick filament
Explanation: Myosin filaments are thick filaments that interact with actin during contraction.
Q35. The process of muscle contraction is best explained by:
a) Fluid mosaic model
b) Sliding filament theory
c) Lock and key hypothesis
d) Chemiosmotic hypothesis
Answer: b) Sliding filament theory
Explanation: The sliding filament theory describes how actin filaments slide over myosin filaments to shorten sarcomeres.
Q36. Which muscle protein forms the backbone of the thin filament?
a) Actin
b) Myosin
c) Troponin
d) Tropomyosin
Answer: a) Actin
Explanation: Actin filaments form the core of thin filaments in a sarcomere.
Q37. The point of contact between motor neuron and muscle fiber is called:
a) Axon terminal
b) Neuromuscular junction
c) Sarcoplasmic reticulum
d) Synaptic cleft
Answer: b) Neuromuscular junction
Explanation: It is the synapse where a motor neuron communicates with a muscle fiber using acetylcholine.
Q38. The contractile protein troponin is absent in:
a) Skeletal muscle
b) Smooth muscle
c) Cardiac muscle
d) All striated muscles
Answer: b) Smooth muscle
Explanation: Smooth muscles lack troponin; contraction is regulated by calmodulin.
Q39. Which band remains unchanged during muscle contraction?
a) I band
b) H zone
c) A band
d) Z line
Answer: c) A band
Explanation: The A band represents the length of myosin filaments, which does not change during contraction.
Q40. Which muscle type is multinucleated?
a) Skeletal muscle
b) Smooth muscle
c) Cardiac muscle
d) Involuntary muscle
Answer: a) Skeletal muscle
Explanation: Skeletal muscle fibers are multinucleated and cylindrical in shape.
Q41. Which of the following is an example of pivot joint?
a) Shoulder joint
b) Hip joint
c) Atlas and axis vertebrae joint
d) Wrist joint
Answer: c) Atlas and axis vertebrae joint
Explanation: The pivot joint between atlas and axis allows rotation of the head.
Q42. Which mineral is essential for muscle contraction apart from calcium?
a) Iron
b) Magnesium
c) Sodium
d) Phosphorus
Answer: b) Magnesium
Explanation: Magnesium is required for ATPase activity in myosin heads, providing energy for contraction.
Q43. What is rigor mortis?
a) Muscular hypertrophy
b) Muscular fatigue
c) Permanent contraction after death
d) Muscular relaxation
Answer: c) Permanent contraction after death
Explanation: Rigor mortis occurs due to lack of ATP, preventing detachment of myosin heads from actin.
Q44. The sliding filament theory was proposed by:
a) Schleiden and Schwann
b) Huxley and Niedergerke
c) Watson and Crick
d) Calvin and Benson
Answer: b) Huxley and Niedergerke
Explanation: Huxley and Niedergerke proposed the sliding filament theory in 1954.
Q45. Which type of joint is found between carpals of the wrist?
a) Hinge joint
b) Gliding joint
c) Saddle joint
d) Pivot joint
Answer: b) Gliding joint
Explanation: The small bones of the wrist move over one another through gliding joints.
Q46. Which muscle controls the movement of the pupil?
a) Skeletal muscle
b) Smooth muscle
c) Cardiac muscle
d) Voluntary muscle
Answer: b) Smooth muscle
Explanation: Smooth muscles in the iris regulate the size of the pupil involuntarily.
Q47. Which structure stores calcium in muscle cells?
a) Sarcolemma
b) Sarcoplasmic reticulum
c) Mitochondria
d) Myofibrils
Answer: b) Sarcoplasmic reticulum
Explanation: The sarcoplasmic reticulum releases calcium ions that trigger muscle contraction.
Q48. Which connective tissue covers an entire skeletal muscle?
a) Epimysium
b) Perimysium
c) Endomysium
d) Fascia
Answer: a) Epimysium
Explanation: Epimysium is the outer covering of the whole muscle.
Q49. Which of the following muscles are involuntary and non-striated?
a) Skeletal muscles
b) Smooth muscles
c) Cardiac muscles
d) All muscles
Answer: b) Smooth muscles
Explanation: Smooth muscles are involuntary, spindle-shaped, and lack striations.
Q50. Which is the strongest and longest bone in the human body?
a) Humerus
b) Tibia
c) Femur
d) Fibula
Answer: c) Femur
Explanation: The femur is the strongest and longest bone, forming the thigh.
Part 3 (Q51–Q75) Human Physiology – Locomotion and Movement
Q51. Which of the following is not a type of joint in the human body?
a) Ball and socket
b) Hinge
c) Pivot
d) Spiral
Answer: d) Spiral
👉 Spiral is not a recognized joint type. Human body joints include hinge (knee), ball and socket (shoulder, hip), and pivot (atlas-axis).
Q52. Which ion is directly responsible for muscle contraction?
a) Sodium
b) Potassium
c) Calcium
d) Chloride
Answer: c) Calcium
👉 Calcium binds to troponin, causing conformational changes that expose actin binding sites for myosin.
Q53. The functional unit of skeletal muscle is:
a) Myofibril
b) Sarcomere
c) Fascicle
d) Muscle fiber
Answer: b) Sarcomere
👉 A sarcomere extends between two Z-lines and is the functional unit responsible for muscle contraction.
Q54. The Atlas bone is articulated with which part of the skull?
a) Temporal bone
b) Occipital bone
c) Frontal bone
d) Parietal bone
Answer: b) Occipital bone
👉 The atlas (C1 vertebra) articulates with the occipital condyles, allowing nodding movement of the head.
Q55. Which protein prevents actin and myosin from interacting in a relaxed muscle?
a) Troponin
b) Tropomyosin
c) Myosin
d) Actin
Answer: b) Tropomyosin
👉 Tropomyosin covers actin’s binding sites; calcium-bound troponin moves tropomyosin, allowing contraction.
Q56. Which of the following bones form the pectoral girdle?
a) Scapula and clavicle
b) Pelvis and sacrum
c) Radius and ulna
d) Femur and tibia
Answer: a) Scapula and clavicle
👉 The pectoral girdle consists of scapula and clavicle, supporting upper limb attachment.
Q57. Which type of movement is allowed by the saddle joint?
a) Only rotation
b) Only flexion
c) Flexion, extension, adduction, abduction
d) No movement
Answer: c) Flexion, extension, adduction, abduction
👉 Saddle joints (e.g., thumb carpometacarpal joint) allow biaxial movement.
Q58. Which of the following bones is the longest in the human body?
a) Humerus
b) Tibia
c) Femur
d) Fibula
Answer: c) Femur
👉 The femur is the longest and strongest bone, supporting body weight during locomotion.
Q59. The sliding filament theory was proposed by:
a) Huxley and Niedergerke
b) Darwin
c) Watson and Crick
d) Schleiden and Schwann
Answer: a) Huxley and Niedergerke
👉 They proposed the sliding filament theory in 1954, explaining actin-myosin interaction in contraction.
Q60. The vertebral column in humans has how many bones?
a) 24
b) 30
c) 26
d) 32
Answer: c) 26
👉 Vertebral column consists of 24 vertebrae, sacrum (1 fused), and coccyx (1 fused) = 26 bones.
Q61. The main function of ligaments is:
a) Connect bone to bone
b) Connect muscle to bone
c) Attach muscles together
d) Connect organs
Answer: a) Connect bone to bone
👉 Ligaments stabilize joints by connecting bones; tendons connect muscles to bones.
Q62. Which of the following is a sesamoid bone?
a) Patella
b) Scapula
c) Sternum
d) Vertebra
Answer: a) Patella
👉 The patella (knee cap) is a sesamoid bone, formed within tendons to reduce friction.
Q63. The human skeletal system is divided into:
a) Axial and appendicular skeleton
b) Upper and lower skeleton
c) Inner and outer skeleton
d) Central and peripheral skeleton
Answer: a) Axial and appendicular skeleton
👉 Axial (skull, vertebrae, ribs, sternum) and appendicular (limbs, girdles).
Q64. Which connective tissue covers muscles?
a) Periosteum
b) Perimysium
c) Epimysium
d) Endothelium
Answer: c) Epimysium
👉 Epimysium surrounds entire muscle, perimysium surrounds fascicles, and endomysium surrounds individual fibers.
Q65. Which muscle type is multinucleated and voluntary?
a) Smooth muscle
b) Skeletal muscle
c) Cardiac muscle
d) None
Answer: b) Skeletal muscle
👉 Skeletal muscle fibers are long, cylindrical, striated, multinucleated, and under voluntary control.
Q66. Which joint allows rotation of the head from side to side?
a) Ball and socket
b) Pivot joint
c) Hinge joint
d) Saddle joint
Answer: b) Pivot joint
👉 The atlas (C1) and axis (C2) form a pivot joint for head rotation.
Q67. Which part of the sarcomere remains constant during contraction?
a) H-zone
b) I-band
c) A-band
d) Z-line
Answer: c) A-band
👉 The A-band (length of myosin filaments) does not change; I-band and H-zone reduce during contraction.
Q68. Which mineral is essential for bone hardness?
a) Sodium
b) Potassium
c) Calcium
d) Sulphur
Answer: c) Calcium
👉 Calcium phosphate (hydroxyapatite) is deposited in bones, making them hard and rigid.
Q69. How many pairs of ribs are present in humans?
a) 10
b) 11
c) 12
d) 13
Answer: c) 12
👉 Humans have 12 pairs: 7 true, 3 false, and 2 floating ribs.
Q70. Which structure connects muscle to bone?
a) Ligaments
b) Tendons
c) Cartilage
d) Fascia
Answer: b) Tendons
👉 Tendons attach muscle to bone, enabling movement by transmitting force.
Q71. Which bone protects the brain?
a) Vertebrae
b) Skull
c) Ribs
d) Sternum
Answer: b) Skull
👉 The skull (cranium) encases and protects the brain.
Q72. Which type of movement occurs at the elbow joint?
a) Rotation
b) Flexion and extension
c) Abduction and adduction
d) Circumduction
Answer: b) Flexion and extension
👉 Elbow is a hinge joint, allowing only flexion and extension.
Q73. What is the main contractile protein in muscles?
a) Myosin
b) Actin
c) Both actin and myosin
d) Tropomyosin
Answer: c) Both actin and myosin
👉 Actin (thin filament) and myosin (thick filament) interact to produce contraction.
Q74. Which region of sarcomere disappears during contraction?
a) A-band
b) I-band
c) H-zone
d) Z-line
Answer: c) H-zone
👉 H-zone (only myosin) disappears as actin slides over myosin during contraction.
Q75. Which type of muscle is involuntary, striated, and branched?
a) Smooth muscle
b) Skeletal muscle
c) Cardiac muscle
d) None
Answer: c) Cardiac muscle
👉 Cardiac muscle is involuntary, striated, branched, and has intercalated discs for coordinated contraction.
Part 4: MCQs (Q76–Q100) Human Physiology – Locomotion and Movement
Q76. The functional unit of skeletal muscle is:
a) Myofilament
b) Sarcolemma
c) Sarcomere ✅
d) M-line
Answer: c) Sarcomere
Explanation: Sarcomere (between two Z-lines) is the structural and functional unit of skeletal muscle responsible for contraction.
Q77. Which of the following ions binds to troponin during muscle contraction?
a) Na⁺
b) Ca²⁺ ✅
c) K⁺
d) Cl⁻
Answer: b) Ca²⁺
Explanation: Calcium ions bind to troponin, causing tropomyosin to move and expose myosin-binding sites on actin filaments.
Q78. The neurotransmitter released at the neuromuscular junction is:
a) Dopamine
b) Acetylcholine ✅
c) Serotonin
d) GABA
Answer: b) Acetylcholine
Explanation: At the neuromuscular junction, acetylcholine is released, which stimulates muscle contraction.
Q79. Which band of a sarcomere shortens during contraction?
a) A-band
b) I-band ✅
c) H-zone ✅
d) M-line
Answer: b) I-band & c) H-zone
Explanation: During contraction, I-band and H-zone shorten, but the A-band remains constant.
Q80. The energy source directly used during muscle contraction is:
a) Glucose
b) ATP ✅
c) Creatine
d) ADP
Answer: b) ATP
Explanation: ATP provides energy for cross-bridge cycling between actin and myosin during muscle contraction.
Q81. Which of the following proteins forms the thin filament of muscle fiber?
a) Myosin
b) Actin ✅
c) Titin
d) Nebulin
Answer: b) Actin
Explanation: Thin filaments are mainly made of actin, along with regulatory proteins troponin and tropomyosin.
Q82. Which of the following is a disorder of the joints?
a) Osteoporosis
b) Gout ✅
c) Tetany
d) Rickets
Answer: b) Gout
Explanation: Gout is due to uric acid crystal deposition in joints, leading to inflammation and pain.
Q83. Which connective tissue sheath covers a bundle of muscle fibers (fascicle)?
a) Epimysium
b) Perimysium ✅
c) Endomysium
d) Sarcolemma
Answer: b) Perimysium
Explanation: Perimysium surrounds each fascicle, epimysium covers the whole muscle, and endomysium covers individual fibers.
Q84. Rigor mortis occurs due to:
a) Excess ATP
b) Lack of ATP ✅
c) Calcium deficiency
d) Low oxygen
Answer: b) Lack of ATP
Explanation: After death, ATP is unavailable to detach myosin heads from actin, leading to permanent contraction (rigor mortis).
Q85. Which part of the brain coordinates body movements?
a) Cerebrum
b) Cerebellum ✅
c) Medulla
d) Hypothalamus
Answer: b) Cerebellum
Explanation: The cerebellum regulates coordination, posture, and balance during body movements.
Q86. Intercalated discs are characteristic of:
a) Skeletal muscle
b) Smooth muscle
c) Cardiac muscle ✅
d) Ligaments
Answer: c) Cardiac muscle
Explanation: Intercalated discs connect cardiac muscle cells and help synchronize contractions.
Q87. Which connective tissue attaches muscles to bones?
a) Ligaments
b) Tendons ✅
c) Cartilage
d) Fascia
Answer: b) Tendons
Explanation: Tendons connect muscle to bone, whereas ligaments connect bone to bone.
Q88. The enzyme that breaks down acetylcholine at synapses is:
a) ATPase
b) Cholinesterase ✅
c) Peptidase
d) Amylase
Answer: b) Cholinesterase
Explanation: Acetylcholinesterase hydrolyzes acetylcholine, allowing muscle relaxation after contraction.
Q89. Which structural protein provides elasticity to muscle sarcomere?
a) Actin
b) Myosin
c) Titin ✅
d) Troponin
Answer: c) Titin
Explanation: Titin is a giant protein that maintains sarcomere elasticity and alignment.
Q90. Which of the following joints is an example of a ball-and-socket joint?
a) Elbow
b) Knee
c) Shoulder ✅
d) Intervertebral
Answer: c) Shoulder
Explanation: The shoulder joint is a ball-and-socket type allowing maximum movement.
Q91. What prevents continuous muscle contraction at the neuromuscular junction?
a) Lack of ATP
b) Release of Ca²⁺
c) Action of acetylcholinesterase ✅
d) Troponin binding
Answer: c) Action of acetylcholinesterase
Explanation: This enzyme breaks down acetylcholine, preventing continuous stimulation.
Q92. Which condition is due to low levels of calcium ions in blood?
a) Rickets
b) Osteoporosis
c) Tetany ✅
d) Arthritis
Answer: c) Tetany
Explanation: Low calcium increases excitability of nerves and muscles, leading to spasms (tetany).
Q93. Which vitamin is essential for calcium absorption in bones?
a) Vitamin A
b) Vitamin D ✅
c) Vitamin K
d) Vitamin E
Answer: b) Vitamin D
Explanation: Vitamin D helps in absorption of calcium and phosphate, essential for bone health.
Q94. Which of the following is not a function of skeletal muscles?
a) Movement
b) Heat generation
c) Blood circulation ✅
d) Posture
Answer: c) Blood circulation
Explanation: Blood circulation is primarily performed by the heart (cardiac muscle), not skeletal muscles.
Q95. The mineral essential for muscle contraction is:
a) Iron
b) Calcium ✅
c) Zinc
d) Copper
Answer: b) Calcium
Explanation: Calcium ions trigger binding of actin and myosin by interacting with troponin.
Q96. Which muscular disorder is characterized by progressive weakening of muscles due to genetic mutation?
a) Myasthenia gravis
b) Muscular dystrophy ✅
c) Tetany
d) Gout
Answer: b) Muscular dystrophy
Explanation: Muscular dystrophy is a genetic disorder where muscles progressively weaken and degenerate.
Q97. Which of the following joints is immovable?
a) Skull sutures ✅
b) Shoulder joint
c) Knee joint
d) Ankle joint
Answer: a) Skull sutures
Explanation: Skull bones are joined by immovable fibrous joints called sutures.
Q98. The synovial fluid is found in:
a) Immovable joints
b) Cartilaginous joints
c) Synovial joints ✅
d) Sutures
Answer: c) Synovial joints
Explanation: Synovial fluid lubricates freely movable joints like knee, shoulder, and hip.
Q99. Myasthenia gravis is an autoimmune disorder affecting:
a) Actin filaments
b) Neuromuscular junction ✅
c) Cardiac muscles
d) Smooth muscles
Answer: b) Neuromuscular junction
Explanation: Myasthenia gravis causes antibodies to block acetylcholine receptors, leading to muscle weakness.
Q100. The functional role of tropomyosin in muscle contraction is:
a) Binding calcium ions
b) Covering myosin-binding sites on actin ✅
c) Hydrolyzing ATP
d) Strengthening sarcolemma
Answer: b) Covering myosin-binding sites on actin
Explanation: Tropomyosin blocks myosin-binding sites in resting state, preventing contraction until Ca²⁺ binds to troponin.
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