Which molecule supplies energy for muscle contraction by transferring its phosphate group to ADP to form ATP?

Correct Answer: A

Rationale: Creatine phosphate stores high-energy phosphate bonds in muscle cells. During contraction, it transfers its phosphate to ADP, regenerating ATP to power myosin heads. Glycogen is a glucose store, myoglobin holds oxygen, and lactic acid is a byproduct, making 'Creatine phosphate' the correct answer.

Correct Answer: D

Rationale: The structure of a bone includes several layers: the periosteum (outer membrane), compact bone (dense outer layer), cancellous bone (spongy inner layer), and bone marrow (innermost part). Bone marrow, found in the medullary cavity of long bones and within cancellous bone, produces blood cells and stores fat, making it the innermost part and 'bone marrow' the correct answer.

Correct Answer: B

Rationale: Tendons are tough, fibrous connective tissues that attach skeletal muscles to bones, transmitting force to enable movement (e.g., Achilles tendon). Ligaments connect bones to bones, cartilage cushions joints, and joints are bone meeting points, not attachments, making 'tendons' the correct answer.

Correct Answer: C

Rationale: The epiphysis is the end of a long bone, containing spongy bone and red marrow, articulating with other bones. The diaphysis is the shaft, the endosteum lines the medullary cavity, and the periosteum covers the exterior, making 'epiphysis' the correct answer.

Correct Answer: A

Rationale: Lamellae are the concentric rings of bone matrix surrounding the central canal in osteons of compact bone, providing strength. Lacunae house osteocytes, canaliculi connect them, and the endosteum lines the interior, making 'lamellae' correct.