The cortex extends in between the medullary pyramids as renal columns called

The origin of the kidney and ureter in $Rana$ $tigrina$ is:

Reabsorption of $Na^+$ and $K^+$ ions does not occur in which of the following?

In the diagram of the human excretory system given below,different parts have been indicated by alphabets. Choose the answer in which these alphabets have been correctly matched with the parts they represent.

Choose the incorrect sentence$(s)$.
$(I)$ Malpighian corpuscles,$PCT$ and $DCT$ of the nephron are situated in the medulla of the kidney.
$(II)$ The loop of Henle dips into the medulla.
$(III)$ In juxtamedullary nephrons,the loop of Henle is too short and extends very little into the medulla.
$(IV)$ Vasa recta is absent or highly reduced in cortical nephrons.

$A$ well-developed Loop of Henle is found in: