What term describes a disorder in which body cells lose the ability to control growth?

• A. Cancer
• B. Tumor
• C. Embryo
• D. Differentiation

Answer: (A)

Uncontrolled cell division due to loss of normal growth control is the hallmark of cancer. Normally, cells stop growing when they should, repair DNA, and undergo programmed cell death if something goes wrong. When mutations disrupt these safeguards—such as in genes that regulate the cell cycle or in tumor suppressors and proto-oncogenes—cells can proliferate without limits, forming cancers that can invade other tissues. A tumor is a lump that may be benign or malignant, but the term describing the disorder of unregulated growth itself is cancer. The other terms refer to different ideas: an embryo is a developing organism, and differentiation is the process by which cells become specialized.