NEET Biology Locomotion and Movement MCQs Set 04

Answer: (a) Unstriped muscles

Explanation:
1. Cardiac muscle is involuntary, like unstriped (smooth) muscle, although it is striated in appearance.
2. So functionally it resembles unstriped muscle.

Teacher's Note:
1. Cardiac: striated but involuntary.
2. Skeletal: striated and voluntary.

Answer: (a) More than other muscles fibres

Explanation:
1. Cardiac muscle works continuously, so its fibres contain more mitochondria than other muscle fibres.
2. These give a steady ATP supply.

Teacher's Note:
1. Cardiac fibres are rich in mitochondria.
2. No rest for the heart.

Answer: (a) Contraction of muscles after death

Explanation:
1. Rigor mortis is stiffening of skeletal muscles after death when ATP runs out and cross bridges cannot detach.
2. It is a contraction after death.

Teacher's Note:
1. No ATP: myosin stays attached.
2. Disappears after tissue breakdown.

Answer: (d) All

Explanation:
1. Unstriped muscle is also called smooth, visceral and involuntary muscle.
2. All three names apply.

Teacher's Note:
1. Found in walls of hollow organs.
2. Cells are spindle shaped.

Answer: (a) White fibrous connective tissue

Explanation:
1. The epimysium, which covers the whole muscle, is made of dense white fibrous connective tissue.
2. It extends into the tendon.

Teacher's Note:
1. Epimysium: outer sheath.
2. Perimysium covers fascicles.

Answer: (a) Gluteus maximus

Explanation:
1. The gluteus maximus of the buttock is the largest muscle of the human body.
2. Stapedius is the smallest.

Teacher's Note:
1. Largest: gluteus maximus.
2. Smallest: stapedius.

Answer: (a) Myosin filament

Explanation:
1. The head of myosin has ATPase activity and hydrolyses ATP to provide energy for the cross-bridge cycle.
2. Actin has no ATPase activity.

Teacher's Note:
1. Myosin: ATPase.
2. Actin: binding sites.

Answer: (b) 639 muscles

Explanation:
1. The human body has about 639 skeletal muscles.
2. This is the commonly accepted number.

Teacher's Note:
1. 639 muscles.
2. 40 to 50 percent of body weight.

Answer: (d) Jaw muscle

Explanation:
1. The jaw muscle (masseter) is the strongest muscle for the force it exerts.
2. The muscles of the thigh and arm are bigger but exert less force relative to size.

Teacher's Note:
1. Masseter closes the jaw.
2. Bite force is large.

Answer: (d) All

Explanation:
1. Cardiac muscle fibres are involuntary, do not fatigue and are striated like skeletal muscle.
2. So all the statements are correct.

Teacher's Note:
1. Cardiac: involuntary, striated.
2. Intercalated discs present.

Answer: (c) Leg

Explanation:
1. Striated (skeletal) muscle fibres occur in the leg.
2. The trachea, lung and gall bladder have smooth muscle.

Teacher's Note:
1. Skeletal: attached to bone.
2. Visceral: smooth.

Answer: (b) Isometric contraction

Explanation:
1. In isometric contraction tension rises but the muscle length stays the same.
2. In isotonic contraction the length decreases.

Teacher's Note:
1. Isometric: same length.
2. Isotonic: same tension.

Answer: (a) Phosphocreatine

Explanation:
1. The phosphagen of vertebrate muscle is phosphocreatine (creatine phosphate), which regenerates ATP.
2. Phosphoarginine is the phosphagen of many invertebrates.

Teacher's Note:
1. Creatine phosphate stores energy.
2. Gives phosphate to ADP.

Answer: (b) Stapedius

Explanation:
1. The stapedius muscle of the middle ear is the smallest muscle in humans and rabbits.
2. It controls the movement of the stapes.

Teacher's Note:
1. Smallest: stapedius.
2. Largest: gluteus maximus.

Answer: (d) Muscle contraction same as threshhold stimulus

Explanation:
1. A muscle fibre follows the all-or-none law, so a supraliminal stimulus gives the same contraction as the threshold stimulus.
2. Stronger stimuli recruit more fibres but do not increase one fibre's response.

Teacher's Note:
1. All-or-none law.
2. Whole muscle: graded response.

Answer: (d) thigh are striated and voluntary.

Explanation:
1. The thigh muscles are skeletal, so they are striated and voluntary.
2. Heart muscle is striated and involuntary, and intestinal muscle is smooth.

Teacher's Note:
1. Skeletal: voluntary.
2. Cardiac: involuntary.

Answer: (c) ATP

Explanation:
1. ATP is the immediate source of energy for muscle contraction.
2. Creatine phosphate regenerates it quickly.

Teacher's Note:
1. ATP: energy currency.
2. Needed for cross-bridge release.

Answer: (b) Lactic acid

Explanation:
1. In prolonged activity muscle respires anaerobically and lactic acid accumulates, causing fatigue.
2. Creatine phosphate and ATPase are not responsible.

Teacher's Note:
1. Lactic acid causes fatigue.
2. Rest removes it.

Answer: (c) Six

Explanation:
1. In a skeletal muscle fibre one myosin filament is surrounded by six actin filaments in a hexagonal arrangement.
2. Each actin filament is shared by three myosin filaments.

Teacher's Note:
1. Ratio: 6 actin to 1 myosin.
2. Seen in cross section.

Answer: (c) Actinin protein

Explanation:
1. The Z disc (Z line) contains actinin, which anchors the thin filaments.
2. Myomesin is found in the M line.

Teacher's Note:
1. Z line: actinin.
2. M line: myomesin.

Answer: (a) Troponin and myosin- Complex proteins in striated muscles

Explanation:
1. Troponin and myosin are complex proteins of striated muscle.
2. Rhodopsin is a pigment protein, calcitonin is a thyroid hormone but thymosin is not, and pepsin and prolactin are not both stomach enzymes.

Teacher's Note:
1. Troponin: calcium binding.
2. Myosin: motor protein.