Question

Metanephros Kidney occurs in
a. Amniotes
b. Fishes
c. Amphibians
d. Invertebrates

Answer 1

The metanephric kidney is the functional kidney in the higher vertebrates. It is composed of nephrons. The structure of nephrons is composed of PCT, DCT, glomerular apparatus, Henle's loop. The type of kidneys varies among the organisms. Such as amniotes have different kidneys than fishes and amphibians. Kidneys filter the blood and waste material from the body, it reabsorbs water and salts and eliminates the waste material.

Complete answer:
In amniotes, the functional kidney is of the Metanephros type. Amniotes are those in which the egg is protected by an amnion membrane. Functional units of Metanephric kidneys are nephrons. Metanephronic kidneys are paired compact organs. The size of the kidney is 10 cm at the age of 12 when it is an adult. An increase or decrease in the size of a kidney is an important symptom of renal disorder.

Fishes and amphibians have mesonephric kidneys.

Invertebrates that are small and live in the water release the waste material from the body by diffusion. Large invertebrates have organs(kidneys) to pass the wastage of the body.

Hence, the correct answer is option (A).

Additional information:
- The function of the nephrons is to filter initial urine from the blood, secrete wastes, and reabsorption of nutrients and water, producing the final urine which is expelled.
- The kidney eliminates the wastes and extra fluid from the body. It also eliminates the acids from the body and maintains the balance of salts, water, and minerals such as calcium, potassium, sodium, and phosphorus.
- The Henle's loop function is the reabsorption of salts and water.

Note: Metanephric kidney arises from the transitional mesoderm. It is a functional and permanent kidney in birds, reptiles, and mammals used for the excretion of the waste material from the body. It develops in the tenth week of human embryonic development and replaces the mesonephros. Kidneys are fully developed at the age of 18 months.