Yellow marrow is best described as?

• A. Red marrow
• B. Spongy bone
• C. Yellow marrow
• D. Compact bone

Answer: (C)

Bone marrow comes in two forms with different roles. Yellow marrow is adipose tissue stored in the medullary cavity of long bones in adults. It mainly serves as an energy reserve by storing fat and is not actively producing blood cells under normal conditions (that function is carried out by red marrow). In certain situations, yellow marrow can convert back to red marrow to increase blood cell production. Spongy bone refers to the porous interior bone tissue, and compact bone is the dense outer shell—these describe bone structure, not the marrow’s content. So yellow marrow is best described as adipose tissue within the medullary cavity.