Error Analysis — Common NEET Traps — Notes

Trap 1: "A band decreases during contraction"

WRONG: A band ALWAYS remains constant. CORRECT: Only I band and H zone decrease.
Why students fall for it: They think A = actin (it doesn't — A stands for anisotropic).

Trap 2: "All striated muscles are voluntary"

WRONG: Cardiac muscle is striated AND involuntary. CORRECT: Striation and voluntary control are independent features.
Why students fall for it: Pattern matching skeletal muscle to all striated muscle.

Trap 3: "Actin filaments shorten during contraction"

WRONG: Neither actin nor myosin filaments change length. CORRECT: Actin SLIDES over myosin (sliding filament theory — no shortening of filaments).

Trap 4: "I band contains both actin and myosin"

WRONG: I band contains ONLY actin. CORRECT: A band contains both (in the overlap zone); I band is actin-only.

Trap 5: "Calcium is released from mitochondria during contraction"

WRONG: Ca2+ is released from the sarcoplasmic reticulum (SR). CORRECT: SR = the Ca2+ store for contraction. Mitochondria supply ATP.

Trap 6: "The hyoid bone is part of the appendicular skeleton"

Trap 7: "ATP hydrolysis causes myosin to detach from actin"

WRONG: ATP binding (not hydrolysis) causes detachment. CORRECT: ATP hydrolysis re-energizes the head; ATP binding causes detachment.

Trap 8: "Tropomyosin directly binds Ca2+ during contraction"

WRONG: Troponin-C binds Ca2+. CORRECT: Troponin-C is the Ca2+ receptor; its conformational change moves tropomyosin.

Trap 9: "Myasthenia gravis is caused by genetic dystrophin deficiency"

WRONG: Dystrophin deficiency causes muscular dystrophy. CORRECT: Myasthenia gravis = autoimmune destruction of ACh receptors. Different disease, different mechanism.

Trap 10: "Osteoarthritis is autoimmune"

WRONG: Rheumatoid arthritis is autoimmune. CORRECT: Osteoarthritis = degenerative wear-and-tear of cartilage. Rheumatoid arthritis = autoimmune attack on synovial membrane.

Trap 11: Smooth muscle has T-tubules — WRONG; it has CAVEOLAE instead.
Trap 12: The M-line bisects the I band — WRONG; Z-line bisects I band; M-line bisects H zone.
Trap 13: Tetany = bacteria (confusion with tetanus) — WRONG; tetany = hypocalcemia; tetanus = bacterial toxin.
Trap 14: Wrist is a ball-and-socket joint — WRONG; wrist = ellipsoid joint; ball-and-socket = shoulder and hip.
Trap 15: Atlas-axis is a hinge joint — WRONG; atlas-axis = pivot joint (rotation only).