Question

red blood cells are highly specialized for their function. which of the following is not a specialized feature of red blood cells?
small diameter
flattened shape
lack of a nucleus
long life span
high hemoglobin content

Explanation:

Red blood cells have a small diameter for easy passage through capillaries, a flattened shape to increase surface - area to volume ratio for gas exchange, lack a nucleus to carry more hemoglobin, and high hemoglobin content for oxygen transport. However, they have a relatively short lifespan (about 120 days), not a long lifespan.

Answer:

long life span