Title Ex-2 excretory Products and their (Solution file).docx.pdf ✅

38 EXCRETORY PRODUCTS AND THEIR ELIMINATION EXERCISE – 2: Previous Year Questions 1. Erythropoietin hormone which stimulates R.B.C. formation is produced by (NEET 2021) (a) Alpha cells of pancreas (b) The cells of rostral adenohypophysis (c) The cells of bone marrow (d) Juxtaglomerular cells of the kidney Ans. (d) Sol. The juxtaglomerular cells of kidney produce peptide hormone called erythropoietin which stimulates erythropoiesis (formation of RBC). 2. Which of the following would help in prevention of diuresis? (NEET 2020) (a) Atrial natriuretic factor causes vasoconstriction (b) Decrease in secretion of renin by JG cells (c) More water reabsorption due to under secretion of ADH (d) Reabsorption of Na + and water from renal tubules due to aldosterone Ans. (d) Sol. • ANF acts as a vasodilator. It acts on the kidney to increase sodium excretion and GFR, to antagonize renal vasoconstriction. • Due to decrease in secretion of renin, it reduced concentration of angiotensin I and II. • ADH facilitates water reabsorption from latter parts of the tubule, thereby preventing diuresis. • Reabsorption of Na + and water from renal tubules due to aldosterone help in prevention of diuresis. 3. Presence of which of the following conditions in urine are indicative of Diabetes Mellitus? (NEET 2020) (a) Uremia and Ketonuria (b) Uremia and Renal Calculi (c) Ketonuria and Glycosuria (d) Renal calculi and Hyperglycemia Ans. (c) Sol. Diabetes mellitus is associated with loss of glucose through urine and formation of harmful compounds known as ketone bodies. Presence of glucose in urine is glycosuria and presence of ketone bodies in urine is ketonuria. 4. The increase in osmolarity from outer to inner medullary interstitium is maintained due to: (i) Close proximity between Henle's loop and vasa recta (ii) Counter current mechanism (iii) Selective secretion of HCO3 – and hydrogen ions in PCT (iv) Higher blood pressure in glomerular capillaries (NEET 2020) (a) only (ii) (b) (i) and (ii) (c) (iii) and (iv) (d) (i), (ii) and (iii) Ans. (b) Sol. The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmolL –1 in the cortex to about 1200 mOsmolL –1 in the inner medulla. This gradient is mainly caused by NaCl and urea. NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of vasa recta. NaCl is returned to the interstitium by the ascending portion of vasa recta. 5. Use of an artificial kidney during hemodialysis may result in (NEET 2019) (i) Nitrogenous waste builds up in the body (ii) Non-elimination of excess potassium ions (iii) Reduced absorption of calcium ions from gastro-intestinal tract (iv) Reduced RBC production Which of the following options is the most appropriate? (a) (ii) and (iii) are correct (b) (iii) and (iv) are correct (c) (i) and (iv) are correct (d) (i) and (ii) are correct Ans. (b)
39 EXCRETORY PRODUCTS AND THEIR ELIMINATION Sol. (i) and (ii) statements are incorrect because dialysis eliminates urea and potassium from the body whereas, (iii) and (iv) are correct. As phosphate ions are eliminated during dialysis, along with that calcium ions are also eliminated. So, there will be reduced absorption of calcium ions from gastrointestinal tract. RBC production will be reduced, due to reduced erythropoietin hormone. 6. Which of the following factors is responsible for the formation of concentrated urine? (NEET 2019) (a) Maintaining hyperosmolarity towards inner medullary interstitium in the kidneys. (b) Secretion of erythropoietin by juxtaglomerular complex. (c) Hydrostatic pressure during glomerular filtration. (d) Low levels of antidiuretic hormone. Ans. (a) Sol. The proximity between loop of Henle and vasa recta as well as counter current in them help in maintaining and increasing osmolarity towards the inner medullary interstitium. This mechanism helps to maintain a concentration gradient in medullary interstitium. So, human urine is nearly four times concentrated than initial filtrate formed. 7. Match the following parts of a nephron with their function: Column I Column II A Descending limb of Henle's loop i. Reabsorption of salts only B Proximal Convoluted tubule ii. Reabsorption of water only C Ascending limb of Henle's loop iii . Conditional reabsorption of sodium ion and water D Distal convoluted tubule iv. Reabsorption of ion, water and organic nutrients (NEET 2018) (a) A-ii, B-iii, C-i, D-iv (b) A-i, B-ii, C-iii, D-iv (c) A-ii, B-iv, C-i, D-iii (d) A-iv, B-i, C-ii, D-iii Ans. (c) Sol. The descending limb of Henle’s loop is permeable to H2O and the ascending limb allows transport of electrolytes. 70-80 % of electrolytes and H2O are reabsorbed by PCT. Conditional reabsorption of Na + and H2O takes place in DCT. 8. Match the items given in column I with those in Column II and select the correct option given below: Column I Column II a. Podocytes i. Crystallized oxalates b. Protonephridia ii. Annelids c. Nephridia iii . Amphioxus d. Renal calculi iv. Filtration slits (NEET 2018) (a) a-ii, b-iii, c-i, d-iv (b) a-i, b-ii, c-iii, d-iv (c) a-iii, b-ii, c-iv, d-i (d) a-iv, b-iii, c-ii, d-i Ans. (d) Sol. Filtration slits between the podocytes perform the filtration function. Protonephridia are found in Amphioxus. Nephridia are an excretory structure of annelids. Renal calculi are an insoluble mass of crystallized salts (oxalates, etc.) 9. Match the items given in column I with those in Column II and select the correct option given below: Column I Column II a . Glycosuria i. Accumulation of uric acid in joints b . Gout ii. Mass of crystallized salts within the kidney c . Renal calculi iii. Inflammation in glomeruli d . Glomerular nephritis iv. Presence of glucose in urine (NEET 2018) (a) a-ii, b-iii, c-i, d-iv (b) a-i, b-ii, c-iii, d-iv (c) a-iii, b-ii, c-iv, d-i (d) a-iv, b-i, c-ii, d-iii Ans. (d)
40 EXCRETORY PRODUCTS AND THEIR ELIMINATION Sol. Glycosuria is the presence of glucose in urine. This happens when there is an extremely high level of glucose in the body and kidneys are not able to absorb all that glucose back into the bloodstream. Gout is a type of arthritis that occurs when there is an accumulation of uric acid in joints. Uric acid accumulates and forms sharp crystals in joints which causes severe pain or swelling. Renal calculi or kidney stones are mass of crystallized salts within the kidney. They are made of calcium oxalate. Glomerular nephritis is the inflammation of the glomeruli. Glomeruli are nodes of tiny blood vessels that are present in the kidney and help in the filtration of blood. Damage in glomeruli can cause kidney failure. 10. Match the items given in Column I with those in Column II and select the correct option given below. Column I (Function) Column II (Part of Excretory system) a. Ultrafiltration i. Henle’s loop b. Concentration of urine ii. Ureter c. Transport of urine iii . Urinary bladder d. Storage of urine iv. Malpighian corpuscle v. Proximal convoluted tubule (NEET 2018) (a) a-v, b-iv, c-i, d-ii (b) a-iv, b-i, c-ii, d-iii (c) a-iv, b- v, c-ii, d-iii (d) a-v, b-iv, c-i, d-iii Ans. (b) Sol. Ultrafiltration takes place in Malpighian corpuscles. Filtration of blood cells and proteins takes place in glomerulus and Bowman’s capsule. Glomerulus and Bowman’s capsule are collectively known as Malpighian corpuscle. Loops of Henle play an important role in the concentration of urine and reabsorption of water. Transportation of urine involves two thin tubes called ureter which transports urine from the kidneys to the urinary bladder. Urine is stored in the urinary bladder. When the bladder is full, the muscle present in the bladder sends a message to the brain so that urine can be excreted out of the body. 11. A decrease in blood pressure/volume will not cause the release of (NEET 2017) (a) Renin (b) Atrial Natriuretic Factor (c) Aldosterone (d) ADH Ans. (b) Sol. A decrease in blood pressure/volume will not cause the release of atrial natriuretic factor (ANF) as it causes the blood pressure to decrease so when the blood pressure is already low, it is not released. As we know, decrease in blood pressure causes activation of renin and aldosterone which increases the blood pressure and will also increase the rate of GFR. ADH also increases the rate of GFR when blood pressure is low. 12. Which of the following statements is correct? (NEET 2017) (a) The ascending limb of loop of Henle is impermeable to water (b) The descending limb of loop of Henle is impermeable to water (c) The ascending limb of loop of Henle is permeable to water (d) The descending limb of loop of Henle is permeable to electrolytes Ans. (a) Sol. The ascending limb of the loop of Henle is impermeable to water but electrolytes are often transported through it. Absorption of sodium, potassium, and chloride ions takes place by active transport. The descending limb of the loop of Henle is impermeable to electrolytes but permeable to water. 13. In mammals, which blood vessel would normally carry largest amount of urea? (NEET 2016) (a) Renal Vein (b) Dorsal Aorta (c) Hepatic Vein (d) Hepatic Portal Vein Ans. (c) Sol. Hepatic veins carry large amounts of urea in mammals. Breakdown of amino acids and proteins takes place within the liver and later is converted to
41 EXCRETORY PRODUCTS AND THEIR ELIMINATION urea. Then the urea is carried out by the liver through hepatic veins. Dorsal aorta transports oxygenated blood to the kidney. Since they carry pure blood, they do not contain any urea. Renal vein is the blood vessel that receives deoxygenated blood from the kidney and returns it to the systemic circulation. Since this vein receives pure blood, it cannot contain urea. Hepatic portal vein transports blood that is drained from the pancreas, small intestine, spleen and stomach to the liver. This blood contains nutrients and toxins that have been extracted from the digested contents. 14. The part of nephron involved in active reabsorption of sodium is (NEET 2016) (a) Distal convoluted tubule (b) Proximal convoluted tubule (c) Bowman’s capsule (d) Descending loops of Henle Ans. (b) Sol. The part of nephron involved in active reabsorption of sodium occurs within the proximal convoluted tubule. In proximal convoluted tubules, 60-70 % reabsorption of water and ions takes place. 15. Human urine is usually acidic because (NEET 2015) (a) Hydrogen ions are actively secreted into the filtrate (b) The sodium transporter exchanges one hydrogen ion for each sodium ion, in peritubular capillaries (c) Excreted plasma proteins are acidic (d) Potassium and sodium exchange generates acidity Ans. (a) Sol. Human urine is typically acidic because hydrogen ions are actively secreted into the filtrate. Urine is a yellowish liquid that contains urea and other waste products and is excreted out of the body. Urine is slightly acidic in nature and its pH of urine is 6. An adult human, on an average, excretes 1-1.5 liters of urine per day. Excess hydrogen ions are removed from the body by kidneys and excrete it within the urine. By this, the urine gets more acidic. 16. Which of the following does not favor the formation of large quantities of dilute urine? (NEET 2015) (a) Alcohol (b) Renin (c) ANF (d) Caffeine Ans. (b) Sol. A fall in glomerular blood flow/glomerular blood pressure can activate the JG cells to release renin which converts angiotensinogen in blood to angiotensin I and further to angiotensin II. Angiotensin II, being a powerful vasoconstrictor, increases the glomerular blood pressure and thereby GFR. Angiotensin II also activates the adrenal cortex to release Aldosterone. Aldosterone causes reabsorption of Na + and water from the distal parts of the tubule and diuresis is prevented. 17. Removal of PCT from the nephron will result in (NEET 2015) (a) No change in quality and quantity of urine (b) No urine formation (c) More diluted urine (d) More concentrated urine Ans. (c) Sol. The removal of proximal convoluted tubule from the nephron results in lack of reabsorption of high threshold substance from renal tubules and obligatory reabsorption of water is also affected leading to more diluted urine. Since proximal convoluted tubule is mainly associated with reabsorption of much water by osmosis, reabsorption of glucose and amino acids by secondary active transport and other salts and ions as Na + , K + , vitamins act by active transport. 18. Which of the following causes an increase in sodium reabsorption in the distal convoluted tubule? (NEET 2014) (a) Increase in aldosterone levels (b) Increase in antidiuretic hormone levels (c) Decrease in aldosterone levels (d) Decrease in antidiuretic hormone levels Ans. (a) Sol. When the body feels a low blood pressure then, the renin-angiotensin mechanism activates which thereby results in the discharge of the aldosterone hormone. Aldosterone is a hormone that mainly helps in the maintenance of electrolytes and blood pressure that is why an increase in aldosterone hormone causes a rise in sodium reabsorption in DCT.