Mature RBCs Perform Membrane Functions but Lack Nucleus and Organelles

Steps:

• Mature red blood cells (RBCs) eject their nucleus and organelles during maturation to maximize space for hemoglobin.
• Active transport relies on plasma membrane pumps like Na+/K+ ATPase, which RBCs retain for ion balance.
• Cell division, phagocytosis, and protein synthesis require nuclear DNA, ribosomes, or cytoskeletal elements absent in mature RBCs.
• Thus, only active transport is feasible without these structures.

Why A is correct:

• Active transport uses ATP-driven membrane proteins for ion gradients, a function preserved in anucleate RBCs to maintain shape and flexibility.

Why the others are wrong:

• B: Cell division needs nuclear DNA replication and mitosis machinery, impossible without a nucleus.
• C: Phagocytosis requires actin cytoskeleton and lysosomes for engulfing particles, both absent in RBCs.
• D: Protein synthesis demands ribosomes and mRNA from a nucleus, which mature RBCs lack.

Final answer: A