AP BIOLOGY

Detailed explanation-1: -Red blood cells contain hemoglobin and are covered with a membrane composed of proteins and lipids. Hemoglobin-an iron-rich protein that gives blood its red color-enables red blood cells to transport oxygen and carbon dioxide. Red blood cells do not have nuclei, allowing for more room for hemoglobin.

Detailed explanation-2: -Answer and Explanation: The answer choice that is NOT characteristic of mature red blood cells is a. Fe++ molecules degrade quickly limiting life span. Iron molecules do not degrade quickly and instead are recycled and used after blood cells die to create more hemoglobin for other blood cells.

Detailed explanation-3: -Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation.

Detailed explanation-4: -Losing the nucleus enables the red blood cell to contain more oxygen-carrying hemoglobin, thus enabling more oxygen to be transported in the blood and boosting our metabolism.

Detailed explanation-5: -The mature human red blood cell is small, round, and biconcave; it appears dumbbell-shaped in profile. The cell is flexible and assumes a bell shape as it passes through extremely small blood vessels.