Which statement is true about white and red blood cells?

Which statement is true about white and red blood cells?

• A. Red blood cells contain mitochondria and nucleus
• B. White blood cells are nucleated; red blood cells are anucleated
• C. Both white and red blood cells have nuclei
• D. White blood cells lack nuclei

Answer: (B)

White blood cells keep their nucleus to support ongoing gene expression and immune functions, while mature red blood cells lose their nucleus (and, in mammals, mitochondria) to maximize space for hemoglobin and to be more flexible through tiny vessels. That combination makes the statement true: white blood cells are nucleated and red blood cells are anucleated. The other ideas conflict with what mature blood cells look like—red blood cells do not have nuclei (and typically lack mitochondria in mammals), white blood cells do have nuclei, and not all blood cells share the same nuclear status.

White blood cells keep their nucleus to support ongoing gene expression and immune functions, while mature red blood cells lose their nucleus (and, in mammals, mitochondria) to maximize space for hemoglobin and to be more flexible through tiny vessels. That combination makes the statement true: white blood cells are nucleated and red blood cells are anucleated. The other ideas conflict with what mature blood cells look like—red blood cells do not have nuclei (and typically lack mitochondria in mammals), white blood cells do have nuclei, and not all blood cells share the same nuclear status.