Which is the first step of urine formation?

Provide the full forms of the following abbreviations:
$(1)$ $GFR$
$(2)$ $mosmol/L$

The liquid which is collected in the cavity of Bowman's capsule is

At which stage of the $Ornithine$ cycle is the enzyme $Arginase$ used?

Urine formation involves:
$I.$ Glomerular filtration
$II.$ Selective reabsorption
$III.$ Tubular secretion
Choose the correct option for the above statements.

Glomerular filtrate is