Answer: Option C. -> Hairpin bend between descending and ascending limbs
:
C
Within the loop of Henle, urine is at the highest concentration at the hairpin bend between descending and ascending limbs.In a human kidney, the concentration of filtrate entering the loop is 300 milliosmols, and this concentration is multiplied to more than 1200 milliosmols at the bottom of the longest loops of Henle in the renal medulla.

Answer: Option B. -> Glucose and proteins
:
B
The blood constituents that remain unchanged in quantity after being circulated through the kidneys are glucose and proteins.

Answer: Option C. -> Polypeptides
:
C
Polypeptides donot get filtered from blood to Bowman’s capsule in Glomerular ultrafiltration.Blood is filtered so finely through these membranes, 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.

Answer: Option C. -> Assertion [A] is True and Reason [R] is True and is a correct explanation to [A].
:
C
Not all of the urea in the body gets filtered and excreted in the filtrate (urine); about 50% is reabsorbed even when urea is the substance we are trying to excrete in the first place. This is basically because urea pulls a lot of water along with it (relatively speaking of course compared to ammonia). Leaving it in the filtrate would prevent water reabsorption and we cannot afford to excrete all that water. Therefore, some urea gets reabsorbed, and effectively the filtrate that moves from the PCT to the loop of Henle remains isosmotic, that is, of the same osmolarity as the fluid in the interstitium and plasma, because water has moved out of the fluid in proportion to the solutes that have been absorbed.

Answer: Option C. -> Increase in aldosterone
:
C
Aldosterone is a hormone secreted by the outer layer of the adrenal gland (the cortex part). Decreased blood volume and interstitial fluid level, resulting in decreased blood pressure, trigger aldosterone secretion. When aldosterone is present in the blood, the epithelial cells of the collecting duct increase reabsorption of$N{a}^{+}$ in the filtrate. Retaining $N{a}^{+}$ raises the osmotic pressure of the blood and reduces water loss from the body. When aldosterone is absent, the same $N{a}^{+}$remains in the filtrate and gets excreted with the urine.

Answer: Option B. -> Passive transport, Osmosis
:
B
Approximately two-thirds of the NaCl and water filtered into Bowman’s capsule is immediately reabsorbed across the walls of the proximal convoluted tubule. This reabsorption is driven by the active transport of $N{a}^{+}$ out of the filtrate and into surrounding peritubular capillaries. $C{l}^{–}$ follows $N{a}^{+}$ passively because of electrical attraction, and water follows them both because of osmosis.

Answer: Option D. -> is reabsorbed into blood
:
D
Only part of the fluid is excreted along with the waste material because 99% of the filtrate is reabsorbed into the blood. Urine consists of water alone 95% and inorganic and organic matter 5%.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.

Answer: Option D. -> Absence of excess creatinine in blood is uremia
:
D
Uremia (uremic syndrome) is a serious complication ofchronic kidney diseaseand acute kidney injury (also known asacute renal failure). It occurs when urea and other waste products build up in the body because the kidneys are unable to eliminate them.It can be defined as an excess ofamino acidand protein metabolism end products, such asureaandcreatinine, in the blood that would be normally excreted in the urine.

Answer: Option A. -> 1 - Pyramids, 2 - Medullary papilla, 3 - Major calyx, 4 - Minor calyx, 5 - Cortex
:
A
Inside the kidney, there are two zones, an outer cortex (5) and an inner medulla. The medulla is divided into a few conical masses called medullary pyramids (1) projecting into the calyces (sing: calyx). The cortex extends in between the medullary pyramids as renal columns called Columns of Bertin.The renal calyces are the chambers of the kidney through which urine passes. The minor calyces (4) surround the apex of the renal pyramids.The point of each pyramid called the papilla (2), projects into a calyx. The cortex contains blood vessels and collecting duct.

Answer: Option A. -> True
:
A
The uricotelic organism excretes uric acid or its salts. In comparison to Ammonia and Urea, Uric acid is the least toxic and the least soluble in water. It can be stored in cells and body tissues without toxic effects and thus needs least water and is highly efficient mode of excretion in comparison to two other methods. Uricotelic organisms include terrestrial arthropods (including insects), lizards, snakes, and birds. The excreta of uricotelic organisms is typically white paste.