Answer: Option A. -> Glomerulus
:
A
The first step in urine formation starts in glomerulus which is a tuft of blood capillaries and this step is knownas glomerular filtration.

Answer: Option C. -> transport urine to urinary bladder.
:
C
Urine is produced by the kidneys. It is then transported by the pair of ureters to the urinary bladder. Inside urinary bladder, urine is stored until it is released out of the body through the urethra.

Answer: Option C. -> Macula densa function as chemoreceptors (sense concentrations of (Na+,K+andCl−) and on sensing higher levels of these ions, release prostaglandins which suppress the granular cells from releasing renin.
:
C
The macula densa cells, sense lower levels of sodium chloride, and release certain prostaglandins, that are local hormones- i.e., signaling molecules like hormones, but which act locally. The prostaglandins trigger the granular cells to release renin and not suppress them.

Answer: Option A. -> Proximal convoluted tubule and mitochondria
:
A
The first part of the tubule, just after the Bowman's capsule, is the proximal convoluted tubule. Brush border cells with multiple microvilli and a massive amount of mitochondria line this tube. This portion of the tubule is one of the largest contributors to electrolyte and water reabsorption. Around 65% of the sodium and water and a little less chloride that were filtered out of the plasmais reabsorbed into the vasa recta in this section.

Answer: Option D. -> The urine will be more dilute
:
D
Henle's loop is associated with reabsorption of water and electrolytes making the urine more concentrated.Special arrangement of Henle’s loop and vasa recta is called the counter current mechanism. This mechanism helps to maintain a concentration gradientin the medullary interstitium. Presence of such interstitial gradient helps
in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine). Human kidneys can produce urine nearly four times concentrated than the initial filtrate formed.

Answer: Option A. -> Impermeable to water and Sodium chloride (NaCl)
:
A
Countercurrent exchanger would not exist if there were not some mechanism to initially make the vasa recta more concentrated at the bottom of the loop. This is accomplished by the loop of Henle. The ascending limb of Henle and the early distal tubule are impermeable to water as indicated by their thick wall. These regions actively transport sodium chloride (NaCl) out of the filtrate and into the surroundings. The NaCl diffuses into the descending limb of the vasa recta. It will not diffuse into the ascending vasa recta because that fluid is already highly concentrated. This is the mechanism that 'multiplies' the concentration of NaCl in the descending vasa recta making the countercurrent exchanger possible

Answer: Option D. -> When someone drinks a lot of water, ADH release is suppressed
:
D
Antidiuretic hormone (ADH) or vasopressin increases the reabsorption of water in the distal convoluted tubule, collecting tubules and collecting ducts of the nephrons in the kidneys. As a result, the reabsorption of water from the glomerular filtrate is increased. When someone drinks alot of water, requirement of absorption of water decreases, so ADH release is suppressed.

Answer: Option C. -> Ultrafiltration, tubular reabsorption and tubular secretion
:
C
Urine formation in humans takes place by three processes - ultrafiltration, tubular reabsorption and secretion. It takes place in the Malpighian corpuscle, Henle’s loop PCT and DCT.Blood is filtered so finely through the membranes of bowman's capsule, that almost all the constituents of the plasma except the proteins pass onto the lumen of the Bowman’s capsule. Therefore, it is considered as a process of ultra filtration.A comparison of the volume of the filtrate formed per day (180 litres per day) with that of the urine released (1.5 litres), suggest that nearly 99 per cent of the filtrate has to be reabsorbed by the renal tubules. This process is called reabsorption. The tubular epithelial cells in different segments of nephron perform this either by active or passive mechanisms.During urine formation, the tubular cells secrete substances like $H^{+}$, $K^{+}$ and ammonia into the filtrate. Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid-base balance of body fluids.

Answer: Option A. -> 1 - Kidney, 2 - Ureter, 3 - Urinary bladder, 4 - Urethra
:
A
The urinary system in humans consists of one pair of kidneys (1) and the corresponding pair of ureters (2) that collect the urine formed and move it to a urinary bladder (3) that stores the urine until it can be excreted out through a tube called the urethra (4).

Answer: Option A. -> Henle's loop
:
A
In the kidney, the loop of Henle is the portion of a nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. The main function of loop of Henle is to create a concentration gradient in the medulla of the kidney