Which statement about bone is true?
A) Astronauts who spend long periods of time in zero gravity experience decalcification of their bones.
B) Osteoclasts are derived from the lineage of cells that produce osteocytes.
C) Most bones are made entirely of compact bone.
D) Once bones have finished growing, they remain the same shape and density until old age, when thinning of the matrix can occur.
E) Osteoclasts lay down bone in layers, creating compact bone.

Question

Quizplus · Accepted Answer

Astronauts who spend long periods of time in zero gravity experience decalcification of their bones due to lack of weight-bearing exercise and exposure to radiation.

Answer: B
 Osteoclasts are derived from the same lineage of cells that produce macrophages, not osteocytes.

Answer: D
 Bones are constantly remodeling throughout life, but in old age, there is usually a higher rate of bone breakdown than new bone formation, leading to a decrease in bone density.

Answer: None of the above are fully true.
 Statement C is false because most bones are made of both compact and spongy bone. Statement E is false because osteoclasts break down bone, while osteoblasts lay down bone.

Which Statement About Bone Is True