Which statement about mature red blood cells is correct?

• A. They have a nucleus
• B. No nucleus; no protein production
• C. They can divide to replace old cells
• D. They contain mitochondria for energy

Answer: (B)

Mature red blood cells are anucleate and lack mitochondria. This design lets them maximize space for hemoglobin to carry oxygen. Without a nucleus, there’s no DNA to transcribe and no ribosomes to translate proteins, so protein production ceases. Without mitochondria, they can’t perform oxidative metabolism and rely on glycolysis for a small amount of ATP, which is enough for their short lifespan but not for growth or repair. As a result, they cannot divide to replace old cells. That’s why the statement describing no nucleus and no protein production is correct. The other options would require a nucleus, the ability to divide, or mitochondria, which mature mammalian red blood cells do not have.