Excretory Products And Their Elimination Multiple Choice Questions

Q1. If kidneys fail to reabsorb water, the effect on tissue would

  • remain unaffected
  • shrink and shrivel
  • absorb water from blood plasma
  • take more oxygen from blood


If kidney fails to reabsorb water, the concentration of urine will be low and urination will be more frequent. This condition is called polyuria. In this condition, the tissues of the body will be dehydrated and shrink.

Q2. Which blood vessel carries the least amount of urea?

  • Pulmonary vein  
  • Renal artery  
  • Renal vein  
  • Hepatic portal vein  


The renal vein carries blood away from the heart and so carries the least amount of urea formed in the blood.

Q3. In Amoeba, osmoregulation occurs by

  • Contractile vacuole
  • Ectoplasm
  • Pseudopodia
  • Hyaloplasm


Amoeba has a contractile vacuole for osmotic equilibrium. The contractile vacuole slowly fills with water from the cytoplasm and, while fusing with the cell membrane, it quickly contracts releasing water to the outside by exocytosis. This process regulates the amount of water present in the cytoplasm of Amoeba.

Q4. In Hydra, waste material of food digestion and nitrogenous waste material are removed from

  • Mouth and mouth
  • Body wall and body wall
  • Mouth and body wall
  • Mouth and tentacles


In Hydra, undigested residues are egested from the coelenteron through the mouth, while ammonia is removed through the general body surface.

Q5. RAAS secretes which of the following hormones?

  • Mineralocorticoids  
  • Glucocorticoids  
  • Both 1 and 2 above  
  • None of the above  


RAAS secretes mineralocorticoids which are hormones synthesised by the adrenal cortex which affects osmotic balance. Aldosterone is a type of mineralocorticoid which regulates sodium levels in the blood.

Q6. The part of nephron impermeable to salt is

  • Descending limb of loop of Henle  
  • Ascending limb of loop of Henle  
  • Collecting duct  
  • DCT  


The first wide part of the descending limb is impermeable to salt ions, urea and water. The second narrow part of the descending limb is impermeable to water.

Q7. A large quantity of fluid is filtered everyday by the nephrons in the kidney. Only about 1% of it is excreted as urine. The remaining 99% is filtrate which

  • Is stored in the urinary bladder
  • Is reabsorbed into the blood
  • Gets collected in the renal pelvis
  • Is lost as sweat


About 99% of the glomerular filtrate is reabsorbed into the blood as it passes through the nephron, and the remaining 1% becomes urine.

Q8. Enteronephric nephridia of earthworms are mainly concerned with

  • Digestion
  • Respiration
  • Osmoregulation
  • Excretion of nitrogenous wastes


In annelids such as earthworms, nephridia are excretory organs. They contain septal nephridia which discharge the excretory fluid into the intestine. So, these are called enteronephric nephridia.

Q9. Which of the following are metabolic wastes of protein metabolism?

  • Urea, oxygen and N2  
  • Urea, NH3 and CO2  
  • Ammonia, urea and creatinine  
  • Nitrogen, urea and CO2  


The nitrogenous compounds through which toxic nitrogen is eliminated from the organisms are ammonia, urea, uric acid and creatinine. All these substances are produced from protein metabolism.

Q10. The main function of Henle’s loop is

  • Passage of urine  
  • Filtration of blood  
  • Formation of urine  
  • Conservation of water  


The main function of Henle’s loop is to reabsorb water and important nutrients in the filtrate. Through the counter-current mechanism, it aims to reduce the volume of water and solutes within the urine without any change in its concentration.

Q11. Juxtaglomerular cells of the renal cortex synthesise a hormone called

  • ADH
  • Oxytocin
  • Renin
  • Urochrome


The cells of juxtaglomerular apparatus (JGA) form a protein called renin. Renin serves as an enzyme in the conversion of plasma protein angiotensinogen into angiotensin I and further to angiotensin II. The renin- angiotensin-aldosterone system maintains homeostasis.

Q12. The liquid which collects in the cavity of Bowman’s capsule is

  • Concentrated urine
  • Blood plasma minus proteins
  • Glycogen and water
  • Urea, glycogen and water


The glomerular filtrate which collects in the Bowman’s capsule contains only corpuscles and plasma proteins. The filtrate is protein-free and cell-free plasma in composition and osmotic pressure.

Q13. Urea synthesis takes place primarily in the liver because

  • NH3 and CO2are present in the liver only.  
  • Hormone ADH is found in the liver only.  
  • Enzyme arginase is present in the liver only.  
  • The kidney is smaller than the liver.  


Urea is formed in the liver by a cyclic process called the urea cycle. Three amino acids, ornithine, citrulline and arginine, participate in this process. Arginine is decomposed to form urea and ornithine in the presence of the enzyme arginase and water. Ornithine is set free for reuse in the urea cycle.

Q14. Glomerular hydrostatic pressure is present in

  • Tubule of kidney  
  • Bowman’s capsule  
  • Malpighian tubule  
  • Glomerulus  


Glomerular hydrostatic pressure is the mechanical pressure exerted on the fluid of plasma, which tends to push the plasma filtrate from the capillaries of the glomerulus into the capsular space.

Q15. Haemodialysis is associated with

  • Liver
  • Spleen
  • Kidney
  • Stomach


Haemodialysis is a method to filter the blood of a person in case of kidney failure. 

Q16. Solenocytes are the main excretory structures in

  • Annelids
  • Molluscs
  • Echinoderms
  • Platyhelminthes


Solenocytes are meant for excretion and osmoregulation in Platyhelminthes.

Annelids have metanephridia for excretion.

Molluscs have kidneys for excretion.

Echinoderms possess no excretory organs as excretion occurs by osmosis or diffusion.

Q17. Filtration of blood takes place at the

  • PCT
  • DCT
  • Collecting ducts
  • Malpighian body


The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and the Bowman’s capsule together (Malpighian corpuscle). The process is called glomerular filtration.

Q18. Proximal and distal convoluted tubules are parts of

  • seminiferous tubules
  • nephron
  • oviduct
  • vas deferens


Each nephron is formed of two parts: Bowman’s capsule and nephric tubule. Nephric tubule is formed of proximal convoluted tubule, loop of Henle and distal convoluted tubule.

Q19. Which of the following is not a nitrogenous waste?

  • Creatinine  
  • Purines  
  • Allantoin  
  • Citrulline  


Purines, creatinine and allantoin are nitrogenous wastes produced inside the body. Citrulline is not a nitrogenous waste. It is an amino acid which participates in the urea cycle.

Q20. The net pressure gradient that causes the fluid to filter out  of the glomeruli into the capsule is

  • 20 mm Hg
  • 75 mm Hg
  • 30 mm Hg
  • 50 mm Hg


About 20% of plasma fluid filters out into the Bowman’s capsule through a thin glomerular- capsular membrane due to a net or effective filtration of about 10-15 mm Hg (approximate value nearing to 20 mm Hg).

Q21. Dialysing unit (artificial kidney) contains a fluid which is almost the same as plasma except that it has

  • High glucose
  • High urea
  • No urea
  • High uric acid


An artificial kidney or haemodialyser is a machine used to filter the blood of a person whose kidneys are damaged. It works on the principle of dialysis. A cellophane tube is suspended in a saltwater solution of the same composition as the normal blood plasma, except that no urea is present.

Q22. Animals which excrete urea produced during metabolism of amino acids are 

  • Ureotelic
  • Uricotelic
  • Ammonotelic
  • Aminotelic


Ureotelic animals – Excrete urea. Example: Amphibians

Uricotelic animals – Excrete uric acid. Examples: Reptiles and insects

Ammonotelic animals – Excrete ammonia. Example: Bony fish 

Aminotelic animals – Excrete excess of amino acids. Examples: Molluscs and echinoderms 

Q23. A terrestrial animal must be able to 

  • Conserve water  
  • Excrete a large amount of salts in urine  
  • Excrete a large amount of water  
  • Actively pump salts out through the skin  


Terrestrial animals such as insects, reptiles and some land crustaceans need to conserve water for their survival. Hence, they excrete waste products through a method which saves water.

Q24. A patient suffering from cholera is given saline drip because

  • Cl− ions are an important component of blood plasma
  • Na+ ions help to retain water in the body
  • Na+ ions are important in the transport of substances across membranes
  • Cl− ions help in the formation of HCl in the stomach for digestion


The cholera toxin from Vibrio cholerae causes a series of metabolic reactions—continuous activation of adenylate cyclase of intestinal epithelial cells. The high concentration of c-AMP triggers continual secretions of Cl−, HCO3− and water into the lumen of the intestine. Administration of saline not only supports the Na-K pump through which water in the cell is restored, but glucose is also symported along with sodium.

Q25. ADH acts on the

  • Collecting tubule of kidney
  • Loop of Henle
  • Collecting ducts of testes
  • None of the above


A decrease in the volume of body fluids stimulates the posterior pituitary lobe to release ADH. This hormone increases the reabsorption of water in the distal convoluted tubule and collecting duct by making them more permeable to water.

Q26. The condition of failure of the kidney to form urine is called

  • Deamination
  • Entropy
  • Anuria
  • None of the above


The condition of failure of the kidney to form urine is called anuria.

Q27. Malpighian tubules are

  • Excretory organs of insects
  • Excretory organs of frogs
  • Respiratory organs of insects
  • Endocrine glands of insects


Insects, centipedes, millipedes and arachnids have Malpighian tubules for excretion.

Q28. The presence of arginase confirms that

  • Urea cycle is operating.  
  • Urea cycle may be operating.  
  • Arginine is being converted to ornithine.  
  • Arginine is being converted to citrulline.  


Urea is formed in the liver by a cyclic process called urea cycle. Three amino acids, ornithine, citrulline and arginine, participate in this process. Arginine is decomposed to form urea and ornithine in the presence of the enzyme arginase and water. Ornithine is set free for reuse in the urea cycle.

Q29. The proximal convoluted tubule (PCT) is lined with

  • Cuboidal epithelium  
  • Columnar epithelium  
  • Simple cuboidal brush border epithelium  
  • Simple ciliated brush border epithelium  


The walls of the proximal convoluted tubule (PCT) consist of a single layer of simple cuboidal cells bearing microvilli on their surface and resting on a basement membrane.

Q30. Haematuria means

  • RBCs in urine
  • WBCs in urine
  • Both 1 and 2 above
  • None of the above


Haematuria means the presence of red blood cells (erythrocytes) in the urine.

Q31. Which of the following amino acids is present in the ornithine cycle?

  • Valine and cystine
  • Arginine and citrulline
  • Glycine and methionine
  • None of the above


The ornithine cycle or urea cycle is a process in which ammonia is converted into urea. Three amino acids participate in this process – ornithine, citrulline and arginine.

Q32. Which of the following is common to the kidneys and the skeleton in mammals?

  • Cortex
  • Medulla
  • Pelvis
  • Radius


In mammalian skeleton, the pelvis is the hip region of the body. In mammalian kidneys, the pelvis is a wide, funnel-like structure.

Q33. Which of the following is an osmoregulator as well as a nitrogenous product?

  • NH 
  • Urea  
  • Uric acid  
  • All of the above  


Urea is a nitrogenous product as well as an osmoregulator. It is an excretory product in man and mammals, Ascaris, earthworm, fish such as shark and sting ray etc. Sharks retain a large quantity of urea in their blood. Therefore, their blood osmotic pressure approaches that of sea water, which minimises water loss from their body. Ammonia is the excretory product in most aquatic arthropods, most aquatic molluscs, bony fish, amphibian tadpoles etc. Uric acid is the excretory product of mostly insects, some land crustaceans, land snails etc.

Q34. Reabsorption of useful substances from glomerular filtrate occurs in

  • collecting tube
  • loop of Henle
  • proximal convoluted tubule
  • all the above


In PCT, complete reabsorption by active transport takes place for glucose. PCT reabsorbs most of the amino acids and Vitamin C, about 70% of Na+ and nearly 75% of K+ and a large amount of Ca2+ from glomerular filtrate. Cl is reabsorbed by diffusion. 70% of water from filtrate is also reabsorbed in PCT by osmosis.

Q35. A condition in which the body’s internal environment remains nearly constant is called

  • Haematoma
  • Hemostasis
  • Haemopoiesis
  • Homeostasis


Homeostasis is the ability to maintain a constant internal environment in response to environmental changes.

Q36. In the ornithine cycle, which of the following wastes are removed from the blood?

  • CO2 and urea
  • Ammonia and urea
  • CO2 and ammonia
  • Urea and urine


Urea is formed in the liver by a cyclic process called the urea cycle. Three amino acids, ornithine, citrulline and arginine, participate in this process. Ornithine combines with ammonia and carbon dioxide to form citrulline and water. Citrulline combines with more ammonia to form arginine and water. Arginine is decomposed to form urea and ornithine in the presence of the enzyme arginase and water. Ornithine is set free for reuse in the urea cycle.

Q37. Uric acid is the chief nitrogenous component of the excretory products of

  • man
  • earthworm
  • cockroach
  • frog


Cockroach excretes uric acid as the chief nitrogenous excretory product.

Man excretes urea as the chief nitrogenous excretory product.

Earthworm excretes urea, ammonia and amino acids

Frog excretes urea.

Q38.The nitrogenous excretory product of frog tadpole is

  • Ammonia
  • Urea
  • Guanine
  • Uric acid


The frog tadpole survives primarily in water. Ammonia is the main excretory product of aquatic animals. So, the nitrogenous excretory product of frog tadpole is ammonia.

Q39. Angiotensinogen is a protein produced and secreted by the

  • Juxtaglomerular (JG) cells
  • Macula dense cells
  • Endothelial cells
  • Liver cells


Angiotensinogen is a component of the renin-angiotensin system (RAS), a hormone system which regulates blood pressure and fluid balance. Angiotensinogen is synthesised in the liver and secreted in the plasma.

Q40. Which is not a basic renal function?

  • Reabsorption
  • Secretion
  • Perfusion
  • Filtration


Reabsorption: An enzyme renin secreted by the kidneys plays an important role in the reabsorption of Na+ in the ascending limb of the loop of Henle. 

Secretion: The kidney secretes an enzyme renin.

Filtration: The kidney selectively filters out the acidic substances from the blood to maintain the correct pH balance.