🩺 NEET🧬 Biology

Locomotion and Movement

8 solved NEET Biology previous year questions on Locomotion and Movement, each with the correct answer and a full explanation.

Which of the following muscular disorder is inherited?

aTetany

bMuscular dystrophy

cMyasthenia gravis

dBotulism

✓ Correct answer: b) Muscular dystrophy

ExplanationProgressive degeneration of skeletal muscle mostly due to genetic disorder is muscular dystrophy whereas tetany is rapid spasm in muscle due to low calcium in body fluid.Myasthenia gravis is an autoimmune disorder leading to paralysis of skeletal muscles.Botulism is rare and dangerous type of food poisoning caused by the toxins formed by bacterium Clostridium botulinum.

Number of cervical vertebrae in camel is:

aMore than that of rabbit

bLess than that of rabbit

cSame as that of whale

dMore than that of horse

✓ Correct answer: c) Same as that of whale

ExplanationMost mammals have seven cervical vertebrae, e.g., camels, giraffes, bats, whales, rabbits, horses and humans.Therefore, number of cervical vertebrae in a camel is same as that of a whale.

Select the correct statement regarding the specific disorder of muscular or skeletal system:

aGout-Inflammation of joints due to extra deposition of calcium

bMuscular dystrophy-Age-related shortening of muscles

cOsteoporosis-Decrease in bone mass and higher chances of fractures with advancing age

dMyasthenia gravis-Auto-immune disorder which inhibits sliding of myosin filaments

✓ Correct answer: c) Osteoporosis-Decrease in bone mass and higher chances of fractures with advancing age

ExplanationMyasthenia gravis: Auto-immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.Muscular dystrophy: Progressive degeneration of skeletal muscle mostly due to genetic disorder.Gout: Inflammation of joints due to accumulation of uric acid crystals.

Glenoid cavity articulates:

aclavicle with scapula.

bhumerus with scapula.

cclavicle with acromion.

dscapula with acromion.

✓ Correct answer: b) humerus with scapula.

Explanation(2) Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint. [New NCERT Class 11th Page no.226]

Lack of relaxation between successive stimuli in sustained muscle contraction is known as

aFatigue

bTetanus

cTonus

dSpasm

✓ Correct answer: b) Tetanus

ExplanationTetanus is a condition where muscle contractions are sustained without relaxation due to rapid, repeated stimuli.This occurs because the muscle does not get enough time to relax between successive impulses, leading to a continuous contraction.Option A (Incorrect - Fatigue): Muscle fatigue occurs when muscles lose their ability to contract due to prolonged activity and energy depletion.Option C (Incorrect - Tonus): Tonus refers to the partial contraction of muscles in a resting state, maintaining posture.Option D (Incorrect - Spasm): A spasm is a sudden, involuntary muscle contraction, which is usually brief and localized.Thus, the correct term for sustained muscle contraction without relaxation is Tetanus.

Calcium is important in skeletal muscle contraction because it:

adetaches the myosin head from the actin filament.

bactivates the myosin ATPase by binding to it.

cbinds to troponin to remove the masking of active sites on actin for myosin.

dprevents the formation of bonds between the myosin cross bridges and the actin filament.

✓ Correct answer: c) binds to troponin to remove the masking of active sites on actin for myosin.

ExplanationThe correct answer is: C. binds to troponin to remove the masking of active sites on actin for myosin.Explanation: Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the active sites on actin.This exposes the binding sites for myosin heads, allowing muscle contraction to proceed.Without calcium, the active sites remain blocked, and contraction cannot occur.

Which of the following are autoimmune disorders? I. Myasthenia gravis II. Rheumatoid arthritis III. Gout IV. Muscular dystrophy V. Systemic Lupus Erythematosus (SLE) Choose the most appropriate answer from the options given below: [NEET 2024]

aII, III & IV only

bIII, IV & V only

cI, II & IV only

dI, II & V only

✓ Correct answer: d) I, II & V only

ExplanationMyasthenia gravis: Auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle.Rheumatoid Arthritis: Autoimmune disease that primarily affects the joints, causing inflammation and pain.Systemic Lupus Erythematosus (SLE): Chronic autoimmune disease that can affect various organs and tissues in the body, causing a wide range of symptoms.

Sliding filament theory can be best explained as:

aactin and myosin filaments do not shorten but rather slide pass each other.

bwhen myofilaments slide pass each other, myosin filaments shorten while actin filaments do not shorten.

cwhen myofilaments slide pass each other actin filaments shorten while myosin filaments do not shorten.

dactin and myosin filaments shorten and slide pass each other.

✓ Correct answer: a) actin and myosin filaments do not shorten but rather slide pass each other.

ExplanationMechanism of muscle contraction is best explained by the sliding filament theory which states that contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments.

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