Final answer:
Mature, circulating erythrocytes do not contain organelles as they lack a nucleus, mitochondria, and endoplasmic reticulum. They are specialized for oxygen transport and carry structural proteins to maintain their shape.
Step-by-step explanation:
The correct answer to the question of whether mature, circulating erythrocytes (RBCs) contain organelles is: No. Mature erythrocytes are highly specialized cells that have expelled nearly all their internal structures by the time they leave the bone marrow and enter circulation.
Unlike other cells, erythrocytes lack a nucleus, mitochondria, and endoplasmic reticulum. This adaptation allows them to maximize space for hemoglobin, increasing their capacity to transport oxygen.
Mature erythrocytes, however, do have structural proteins like spectrin, which allows them to maintain their shape and deform as necessary to navigate the narrow capillaries.
Regarding the multiple-choice question, the correct statement about mature, circulating erythrocytes is: a. They have no nucleus.
Erythrocytes are packed with hemoglobin, not mitochondria, and they actually survive for about 120 days, not 4 days, making option 'a' the only accurate statement out of those provided.