Are metatarsal bones numbered one through four or five?

Correct Answer: B

Rationale: Metatarsals are numbered 1 to 5, from the hallux (big toe) to the pinky toe, matching the five digits of the foot and their phalanges.

Correct Answer: B

Rationale: A muscle fiber contains myofibrils, which are composed of repeating units called sarcomeres. The sarcomere is the smallest structural unit of a muscle that can contract, defined as the segment between two Z-lines, where actin and myosin filaments interact to produce contraction. Myosin and actin are proteins within the sarcomere, not contractile units themselves, making 'Sarcomere' the correct answer.

Correct Answer: C

Rationale: The appendicular skeleton, comprising the limbs and girdles, is primarily responsible for facilitating movement and locomotion. Bones like the femur and humerus enable walking and arm motion, while the pectoral and pelvic girdles anchor these limbs. Protection of the brain and spinal cord is an axial skeleton function, making 'Facilitating movement and locomotion' the correct answer.

Correct Answer: C

Rationale: The axial skeleton includes the skull, vertebral column, and rib cage. The vertebral column, a series of vertebrae, forms a bony canal that encases and protects the spinal cord. The rib cage protects thoracic organs, the skull protects the brain, and the pelvic girdle is appendicular, making 'Vertebral column' the correct answer.

Correct Answer: A

Rationale: ATP (adenosine triphosphate) provides the energy for muscle contraction by binding to myosin heads, allowing them to detach from actin and re-cock for another pull. Glucose is a fuel source, oxygen supports aerobic respiration, and lactic acid is a byproduct, making 'ATP' the correct answer.