$(a)$ Draw a diagram of the human excretory system and label the following: Aorta,Vena cava,Urinary bladder,Urethra.
$(b)$ List two vital functions of the kidney.

(N/A) The diagram of the human excretory system is provided in the image.
$(b)$ Two vital functions of the kidneys are:
$(i)$ They maintain the $pH$ and salt concentration of the body constant,and also regulate the water balance.
$(ii)$ They help in the removal of nitrogenous waste products (like urea) that are harmful to the human body.