Skeletal & Muscular System — Biology

Q.1

WBCS Prelims 2018

Muscle fatigue is due to accumulation of

A. Carbon Dioxide

B. Creatinine

C. Lactic acid

D. Ethyl alcohol

Explanation

Why Correct: Lactic acid (C3H6O3) accumulates in muscles during anaerobic respiration when oxygen supply is insufficient, lowering pH and causing fatigue.
Distractor Analysis: Carbon dioxide buildup occurs during normal aerobic respiration but doesn't directly cause muscle fatigue. Creatinine is a waste product from muscle metabolism excreted by kidneys. Ethyl alcohol results from fermentation in yeast, not human muscle metabolism.
Takeaway: Anaerobic respiration in human muscles produces lactic acid, while in yeast it produces ethanol and carbon dioxide.

Answer or skip previous question to unlock.

Q.2

WBCS Prelims 2016

A muscle that is consciously controlled :

A. Striated voluntary

B. Striated involuntary

C. Non-striated voluntary

D. Non-striated involuntary

Explanation

Why Correct: Skeletal muscles are striated (striped appearance) and under voluntary control via the somatic nervous system.
Distractor Analysis: Striated involuntary muscles are cardiac muscles, non-striated voluntary muscles do not exist in humans, and non-striated involuntary muscles are smooth muscles found in internal organs.
Takeaway: Cardiac muscle is striated but involuntary, while smooth muscle is non-striated and involuntary.

Answer or skip previous question to unlock.

Q.3

WBCS Prelims 2013

The number of cervical vertebrae in mammal is —

A. Seven

B. Seventeen

C. Seventy seven

D. Eleven

Explanation

Why Correct: All mammals except manatees and sloths have exactly seven cervical vertebrae, regardless of neck length.
Distractor Analysis: Seventeen approximates total thoracic and lumbar vertebrae, seventy-seven is implausible, and eleven occurs in some birds but not mammals.
Takeaway: Giraffes also have seven cervical vertebrae, just elongated; this constancy is a key mammalian characteristic distinguishing them from reptiles and birds.

Answer or skip previous question to unlock.

Q.4

WBCS Prelims 2010

Haversian system is a part of

A. Kidney

B. Bone

C. Heart

D. Brain

Explanation

Why Correct: Haversian canals form the central channels in osteons, which are the structural units of compact bone tissue, providing blood supply and innervation.
Distractor Analysis: Kidney contains nephrons with renal tubules, heart has coronary arteries and cardiac muscle fibers, and brain contains neurons and glial cells with different microstructures.
Takeaway: Osteoclasts resorb bone, osteoblasts build bone matrix, and osteocytes maintain bone tissue within lacunae connected by canaliculi.

Answer or skip previous question to unlock.

Q.5

WBCS Prelims 2003

Colles’ fracture is associated with

A. Humerus

B. Radius

C. Ulna

D. Femur

Explanation

Why Correct: Colles' fracture specifically refers to a distal radius fracture, typically occurring about 2.5 cm proximal to the wrist joint.
Distractor Analysis: Humerus fractures include supracondylar and shaft fractures. Ulna fractures often involve the olecranon or shaft. Femur fractures occur in the thigh bone, commonly from high-impact trauma.
Takeaway: Smith's fracture is the reverse Colles' fracture with volar displacement, while Barton's fracture involves the articular surface of the distal radius.

Sign in to Papersetters