The primary or main excretory organ in humans is:

The wall of the urinary bladder in humans shows a thick layer of smooth muscle called . . . . . . .

Match the following columns:

Column-$I$	Column-$II$
$P$. Structures in renal cortex	$I$. Descending limb of Henle
$Q$. Structures in renal medulla	$II$. Proximal convoluted tubule $(PCT)$
	$III$. Distal convoluted tubule $(DCT)$
	$IV$. Ascending limb of Henle
	$V$. Collecting duct
	$VI$. Duct of Bellini
	$VII$. Afferent arteriole
	$VIII$. Efferent arteriole

Which of the following structures are situated in the cortical region of the kidney?
$I.$ Malpighian corpuscle
$II.$ $PCT$ (Proximal Convoluted Tubules)
$III.$ $DCT$ (Distal Convoluted Tubules)
$IV.$ Loop of Henle
$V.$ Collecting duct

Select the correct statements from the following.
$(i)$ Renal papilla is a narrow tip of the medullary pyramid.
(ii) Renal cortex is red-coloured and striated.
(iii) Longitudinal-circular-longitudinal arrangement of smooth muscles is observed in the renal pelvis at its origin.
(iv) Ureter is a long,non-muscular hollow tube that communicates with the renal pelvis at its origin.

Read the following four statements $(A-D)$ and select the correct ones:
$(A)$ The medulla of the kidney is divided into a few conical masses projecting into the calyces.
$(B)$ The cortex of the kidney extends in between the medullary pyramids as renal columns called columns of Bertini.
$(C)$ The kidneys are situated in the ventral part of the thoracic region in the human body.
$(D)$ Each kidney of an adult human measures $10-12 \ cm$ in length,$5-7 \ cm$ in width,$2-3 \ cm$ in thickness,with an average weight of $120-170 \ gm$.