Question

Renal Portal System is absent in
A. Amphibians
B. Reptiles
C. Both Amphibians and Reptiles
D. Mammals

Answer 1

Hint: The renal portal system which is basically the venous system found in all major living vertebrates. The animals in which this system is present, their veins carry the blood to capillary system in the kidneys. The blood is collected from all parts of the hindlimbs and then transported to the kidneys.

Complete step by step answer:
In order to explain the renal portal system in amphibians, let us take the example of a frog. In amphibians, the blood is collected from the femoral, sciatic, pelvic and external iliac veins and then through the renal portal vein, the impure blood is transported to the kidneys.
In reptiles, the blood moves through two routes. The first is through an Aorta and the second route is from the back half of the body through the kidneys and returns back to the heart.
Hence, both animals and reptiles are animals in which the renal portal system is present.
In the case of mammals, however, the heart is four chambered and hence there is a total separation of oxygenated and deoxygenated blood. Therefore, we can say that the Renal Portal System is absent in mammals as they do not require it.

Option D is correct.

Note:
It should be noted that mammals are the most evolved division of kingdom Animalia. In this way, it is clear that there is no need for a Renal Portal System in the animals with higher levels of organ system and function. Their body has a proper structural circulatory organ system.