Question

Frogs differ from humans in possessing

• A. Paired cerebral hemispheres
• B. Hepatic portal system
• C. Nucleated red blood cells
• D. Thyroid as well as parathyroid

Answer 1

Answer: (C)

Mammals have red blood cells lacking a nucleus. Other vertebrates, such as fish, reptiles and birds, have red blood cells that contain an inactive nucleus. Since carrying oxygen is the primary function of red blood cells, losing the nucleus means that these cells can pack more hemoglobin molecules per unit body weight. Frogs have a nucleus because they don't need much oxygen. Humans don't have a nucleus in their red blood cells because they need more oxygen than frogs, so our red blood cells eliminated the nucleus to fit more oxygen in. Frogs can breathe underwater and in air, so they don't need much oxygen, so their red blood cells didn't eliminate the nucleus.

Hence the correct option is C.