The term 'compact bone' refers to bone tissue that is:

Correct Answer: B

Rationale: Compact bone, also called cortical bone, is the dense, hard outer layer of bone tissue that provides strength and structural support. Spongy bone (with trabeculae) is lighter and found inside, often in the epiphysis, but 'compact bone' specifically denotes the dense type, making 'Dense and hard' the correct answer.

Correct Answer: C

Rationale: The sarcoplasmic reticulum, a specialized endoplasmic reticulum in muscle cells, stores calcium ions and releases them into the cytoplasm upon a nerve signal. This calcium triggers contraction by binding to troponin. It doesn’t produce ATP or contract myofibrils, making 'Storing and releasing calcium ions' correct.

Correct Answer: B

Rationale: The radius and ulna, forearm bones, are part of the appendicular skeleton, which includes the limbs and girdles. They are long bones but belong to the appendicular division, not axial. 'Long bones' is a type, not a division, making 'Appendicular skeleton' correct.

Correct Answer: A

Rationale: Bones are living tissues, not inert structures. They contain cells like osteocytes, osteoblasts, and osteoclasts that maintain bone structure, repair damage, and regulate mineral content. Blood vessels and nerves within bones also support their living functions, such as growth and remodeling, making 'True' the correct answer.

Correct Answer: B

Rationale: The human body has three muscle types: smooth (involuntary, in organs), cardiac (involuntary, in the heart), and skeletal (voluntary, attached to bones). 'Rough muscle' is not a recognized category in anatomy; it may confuse with muscle texture but isn’t a type, making 'rough muscle' the correct answer for what is NOT a muscle type.