The functions of the appendicular skeleton include:

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: 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.

Correct Answer: A

Rationale: In muscle contraction, the sliding filament theory states that actin and myosin filaments slide past each other, shortening the sarcomere (the distance between Z-lines). This shortening contracts the muscle. It does not lengthen, stay unchanged, or vibrate, making 'It shortens' the correct answer.

Correct Answer: B

Rationale: Carpals and tarsals are short bones, roughly equal in length and width, providing stability and flexibility in wrist and ankle joints. They are not irregularly shaped (like vertebrae) but are classified as short, making 'Short bone' the correct answer despite the question’s phrasing.

Correct Answer: B

Rationale: In the sliding filament theory, ATP binds to myosin heads, causing them to detach from actin after a power stroke. This allows the cycle to repeat. Calcium initiates binding, acetylcholine triggers the process indirectly, and sodium is unrelated, making 'ATP' the correct answer.