Where does the increase in the length of a long bone take place? At the :

Correct Answer: B

Rationale: Long bone growth occurs at epiphyseal plates (cartilage), where bone is added distally and removed proximally until ossified in adults. Answer is B, per the document.

Correct Answer: A

Rationale: Synovial joints have synovial fluid in a cavity between bones, enabling free movement—not immovable, tendon-held, or only ball-and-socket. Answer is A, per the document.

Correct Answer: B

Rationale: The average adult human has 206 bones, a standard anatomical count after fetal bones fuse (e.g., sacrum). 33 is the vertebral column, 639 is muscles, and variation is minimal post-development, making '206' correct.

Correct Answer: D

Rationale: The medullary cavity in long bones contains bone marrow (red for blood production, yellow for fat). Air isn’t present, blood is in vessels, cells are in matrix—not the cavity. 'Bone marrow' is correct.

Correct Answer: C

Rationale: Bone elongation during growth occurs at the epiphyseal plate (growth plate), where chondrocytes undergo mitosis, producing new cartilage that is later ossified into bone. Articular cartilage covers bone ends for joint movement, the periosteum supports bone growth in width, and diploe is spongy bone in flat bones—none of these are primary sites for elongation.