The total number of minor calyces in a human kidney is equal to the number of:

Arrange the following parts of the nephron in a sequential manner and select the correct option accordingly.
$I.$ Glomerulus
$II.$ Bowman's capsule
$III.$ Henle's loop
$IV.$ Proximal convoluted tubule $(PCT)$
$V.$ Collecting duct
$VI.$ Distal convoluted tubule $(DCT)$

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.

Provide definitions/explanations for the following terms:
$(1)$ Column of Bertini
$(2)$ Excretory unit (nephron)

Write a short note on the types of nephrons.

Human kidney has