Q1. The following substances are the excretory products in animals. Choose the least toxic from among them.
- 1) Carbon dioxide
- 2) Ammonia
- 3) Urea
- 4) Uric acid
The toxicity of excretory products is as follows: Ammonia ˃ Urea ˃ Uric acid Carbon dioxide is a respiratory product and is eliminated through diffusion from the body.
Q2. The kidney of an adult frog is
- 1) Pronephros
- 2) Mesonephros
- 3) Opisthonephros
- 4) Metanephros
A mesonephric kidney consists of a large number of tubules which develop internal glomeruli enclosed in capsules forming Malpighian bodies. In amphibians, it is functional in both embryo and adult.
Q3. Enteronephric nephridia of earthworms are mainly concerned with
- 1) Osmoregulation
- 2) Digestion
- 3) Respiration
- 4) 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.
Q4. Where do you find the slit pores in the Bowman’s capsule?
Slit pores are present between the podocytes in Bowman’s capsule.
Q5. Name the disorder in which glucose is present in excess quantities in urine.
Q6. Name any two classes of uricotelic animals of the phylum Chordata.
Reptiles and birds
Q7. The main function of Henle’s loop is
- 1) Conservation of water
- 2) Passage of urine
- 3) Formation of urine
- 4) Filtration of blood
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.
Q8. Haematuria means
- 1) None of the above
- 2) WBCs in urine
- 3) RBCs in urine
- 4) Both 1 and 2 above
Haematuria means the presence of red blood cells (erythrocytes) in the urine.
Q9. State the condition in which urea gets accumulated in the blood.
Q10. Distinguish between ammonotelism and ureotelism.
Ammonotelism Ureotelism Waste products are excreted in the form of ammonia. Waste products are excreted in the form of urea. Elimination of ammonia requires more water. Elimination of uric acid requires moderate amount of water. Ammonia is highly toxic. Urea is less toxic than ammonia. Aquatic amphibians, bony fish and aquatic insects exhibit ammonotelism. Marine fish, mammals and terrestrial amphibians exhibit ureotelism.
Q11. The liquid which collects in the cavity of Bowman’s capsule is
- 1) Concentrated urine
- 2) Urea, glycogen and water
- 3) Blood plasma minus proteins
- 4) 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.
Q12. If kidneys fail to reabsorb water, the effect on tissue would
- 1) take more oxygen from blood
- 2) shrink and shrivel
- 3) remain unaffected
- 4) absorb water from blood plasma
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.
Q13. Name the excretory organs found in the following organisms: Earthworm Liver fluke Prawns Cockroach
Animal Excretory Organs Earthworm Nephridia Liver fluke Flame cells Prawns Green/antennal glands Cockroach Malpighian tubules
Q14. Name the largest gland of the human body.
Q15. The yellow colour of urine is due to
- 1) Urochrome
- 2) Uric acid
- 3) Bilirubin
- 4) Urea
The yellow colour of urine is due to the pigment urochrome derived from the breakdown of haemoglobin from worn-out RBCs.
Q16. The condition of failure of the kidney to form urine is called
- 1) None of the above
- 2) Anuria
- 3) Entropy
- 4) Deamination
The condition of failure of the kidney to form urine is called anuria.
Q17. What is uraemia? Name and describe the process used to remove waste substances from individuals suffering from uraemia.
Uraemia is the accumulation of urea in the blood due to malfunctioning of the kidneys. In individuals suffering from uraemia, the waste substances are removed by haemodialysis. In this process, blood is drained from the convenient artery (usually radial artery), mixed with anticoagulant such as heparin and pumped into the dialysing unit. The dialysing unit consists of a coiled tube surrounded by a dialysing fluid.
The dialysing unit has the same composition as that of the plasma membrane, but it does not contain any nitrogenous waste. The absence of nitrogenous water in the dialysing unit enables the easy movement of waste from urine into the tube through the porous membrane, thus clearing the blood from any waste. The cleared blood is then pumped back into the body through the same vein after adding anti-heparin.
Q18. State the type of epithelium which lines the inner wall of PCT.
Simple cuboidal brush border epithelium
Q19. Explain micturition.
The process of release of urine is called micturition. When the urinary bladder gets filled with urine, the stretch receptors present on the walls of the bladder send signals to the central nervous system (CNS). In response to these signals, CNS sends the motor message which causes the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincters. This results in the release of urine from the body.
Q20. Different organs perform the role of excretory organs in different animals. Give the names of such two excretory organs and the names of animals in which these organs are found. Explain the role of the excretory organ of the cockroach in detail. What value do you learn from (a)?
Planaria Flame cells Amphioxus Protonephridia Earthworm Nephridia Antennal glands Prawns Cockroach Malpighian tubules Malpighian tubules in cockroaches remove the nitrogenous waste products and also maintain the ionic and fluid balance in the body.
Although there are different organs in different animals, they perform the same function. Similarly, there are human beings of different caste and religion. We must not forget that all are equal, and we should treat every person equally well.
Q21. State the role of the distal convoluted tubule in urine formation.
The distal convoluted tubule (DCT) is responsible for the absorption of HCO3− ions and the secretion of H+ ions, K+ ions and ammonia to maintain the pH of urine and the sodium-potassium balance in the blood. DCT is also responsible for the conditional reabsorption of sodium ions and water.
Q22. Animals which excrete urea produced during metabolism of amino acids are
- 1) Ammonotelic
- 2) Ureotelic
- 3) Uricotelic
- 4) 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. What is ketonuria?
Ketonuria is a disorder in which ketone bodies are observed in the urine. It is an indication of diabetes.
Q24. State the role of Henle’s loop in urine formation.
Henle’s loop maintains high osmolarity of the medullary interstitial fluid.
Q25. Name the neural mechanism responsible for micturition.
Q26. A patient suffering from cholera is given saline drip because
- 1) Na+ ions help to retain water in the body
- 2) Cl− ions are an important component of blood plasma
- 3) Na+ ions are important in the transport of substances across membranes
- 4) 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.
Q27. In Hydra, waste material of food digestion and nitrogenous waste material are removed from
- 1) Mouth and body wall
- 2) Mouth and mouth
- 3) Body wall and body wall
- 4) Mouth and tentacles
In Hydra, undigested residues are egested from the coelenteron through the mouth, while ammonia is removed through the general body surface.
Q28. Name the part of the nephron which is situated in the medulla of the kidney.
Q29. Distinguish between ammonotelism and uricotelism.
Ammonotelism Uricotelism Waste products are excreted in the form of ammonia. Waste products are excreted in the form of uric acid. Elimination of ammonia requires more water. Elimination of uric acid requires less amount of water. Aquatic amphibians, bony fish and aquatic insects exhibit ammonotelism. Reptiles, birds, insects and land snails exhibit uricotelism.
Q30. Which one of the following options shows a correct matching pair?
- 1) Man – Ureotelic
- 2) Fish – Uricotelic
- 3) Frog – Uricotelic
- 4) Birds – Ammonotelic
Man – Ureotelic Birds – Uricotelic Fish – Ammonotelic Frog – Ureotelic
Q31. State the osmolarity of the filtrate in the cortex of the kidney.
Q32. Solenocytes are the main excretory structures in
- 1) Echinoderms
- 2) Annelids
- 3) Platyhelminthes
- 4) Molluscs
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.
Q33. What is the GFR of a healthy individual?
GFR (i.e. the glomerular filtration rate) of a healthy individual is 125 ml/minute, i.e. 180 litres/day.
Q34. What is the juxtaglomerular apparatus?
The juxtaglomerular apparatus is a sensitive region which is formed due to the cellular modifications in the distal convoluted tubule and the afferent arteriole at the region of their contact.
Q35. When a fresh water protozoan possessing a contractile vacuole is placed in a glass containing marine water, the vacuole will
- 1) Increase in number
- 2) Decrease in size
- 3) Disappear
- 4) Increase in size
When freshwater protozoa are placed in marine water (hypertonic), the contractile vacuoles disappear because of the absence of endosmosis. So, water does not enter the protoplasm.
Q36. The proximal convoluted tubule (PCT) is lined with
- 1) Cuboidal epithelium
- 2) Columnar epithelium
- 3) Simple cuboidal brush border epithelium
- 4) 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.
Q37. Name the notch present on the inner concave surface of the kidney.
Q38. A parrot and a dog were fed only a protein-rich diet. In what forms would they excrete nitrogenous wastes?
The parrot will excrete uric acid, while the dog will excrete urea.
Q39. In protozoa such as Amoeba and Paramecium, an osmoregulatory organelle is
- 1) Nucleus
- 2) Food vacuole
- 3) Mitochondrion
- 4) Contractile vacuole
Amoeba and Paramecium use the contractile vacuole for excretion. These are freshwater animals (hypotonic solution). Water flows from the outside to the inside of the body of the organism. The contractile vacuoles in these organisms collect excess water and gradually increase in size. When the vacuoles reach a critical size, they contract, squeezing out their contents through the process of diffusion.
Q40. Name any two substances which are reabsorbed in the renal tubule by active mechanisms.
Glucose and amino acids
Q41. Malpighian tubules are
- 1) Excretory organs of insects
- 2) Respiratory organs of insects
- 3) Excretory organs of frogs
- 4) Endocrine glands of insects
Insects, centipedes, millipedes and arachnids have Malpighian tubules for excretion.
Q42. Name the excretory organs in fish.
Body surface and gills
Q43. What are ammonotelic animals? Give any two examples.
Animals which excrete nitrogenous waste products in the form of ammonia are called ammonotelic animals. Examples: Bony fish, aquatic insects
Q44. Explain the counter-current mechanism.
The flow of the glomerular filtrate in the two limbs of Henle’s loop and the vasa recta is in a counter-current pattern. NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of the vasa recta.
NaCl is returned to the interstitium by the descending portion of the vasa recta. Similarly, minute quantities of urea enter the thin segment of Henle’s loop which is transported back to the interstitium by the collecting tubule. The counter-current pattern and the proximity between the Henle’s loop and the vasa recta help to maintain the osmolarity in the inner medullary interstitium, i.e. 300 mOsmoiL−1 in the cortex and 1200 mOsmoiL−1 in the medulla. This process is called the counter-current mechanism.
Q45. Name the disorder which can be diagnosed by the presence of ketone bodies in urine.
Q46. Name any one animal in which antennal glands act as excretory organs.
Q47. Name the branch of the renal artery which enters the glomerulus.
Q48. What are podocytes?
Podocytes are the epithelial cells which line the Bowman’s capsule.
Q49. Describe the structure of the Malpighian body.
The Malpighian body constitutes the glomerulus and Bowman’s capsule. The glomerulus is a tuft of blood capillaries. The afferent arteriole enters the glomerulus, while the efferent arteriole leaves the glomerulus. The Bowman’s capsule is a cup-shaped structure. The glomerulus is situated in the cup-shaped depression of the Bowman’s capsule.
Q50. State the osmolarity of the filtrate in the medulla of the kidney.
Q51. What structures constitute the Malpighian body?
The glomerulus and the Bowman’s capsule constitute the Malpighian body.
Q52. Name the columns of the cortex which extends between the renal pyramids.
Columns of Bertini
Q53. How much blood is filtered per minute by the kidneys?
Q54. Name the excretory organ of Planaria.
Q55. Name the three processes involved in urine formation.
The three processes involved in urine formation are glomerular filtration, reabsorption and secretion.
Q56. Name the functional unit of the human excretory system.
Q57. State the function of protonephridia in amphioxus.
Protonephridia in amphioxus maintain the ionic and fluid volume, i.e. protonephridia play an important role in osmoregulation.
Q58. Distinguish between uricotelism and ureotelism.
Uricotelism Ureotelism Waste products are excreted in the form of uric acid. Waste products are excreted in the form of urea. Elimination of uric acid requires less amount of water. Elimination of uric acid requires moderate amount of water. It is the least toxic substance. It is a moderately toxic substance. Reptiles, birds, insects and land snails exhibit uricotelism. Marine fish, mammals and terrestrial amphibians exhibit ureotelism.
Q59. Describe the criteria for kidney transplantation.
The patients with terminal renal failure are eligible for kidney transplantation. The persons at risk from a life-threatening disease are not eligible for kidney transplantation.
Q60. State the function of rennin.
Renin stimulates the glomerular blood flow to bring the glomerular filtration rate back to normal.
Q61. Name the nitrogenous waste product which requires a large amount of water for its elimination.
Q62. What is sweat? What does it contain? State its function.
Sweat is a watery fluid secreted by the sweat glands located in the skin. Sweat contains NaCl, urea in small amount and lactic acid. Functions of sweat: Sweat facilitates the cooling effect on the body surface. It helps to remove some excretory substances from the body such as lactic acid, urea etc.
Q63. Name the enzyme secreted by the juxtaglomerular cells.
Q64. Name a vasoconstrictor which increases the glomerular blood pressure.
Q65. Name the three layers through which blood is filtered during glomerular filtration.
Layers through which blood filters during glomerular filtration are Endothelium of glomerular blood vessels Epithelium of Bowman’s capsule Basement membrane present between the endothelium of the glomerulus and the epithelium of Bowman’s capsule
Q66. Explain how the glomerular filtration rate is maintained by the kidneys?
Maintenance of the glomerular filtration rate is carried out by the juxtaglomerular apparatus in the kidneys. It is the region formed by the close contact between the distal convoluted tubule and the afferent arteriole at a region. When GFR falls, it stimulates JGA to release rennin. Renin helps to bring reduced GFR back to normal.
Q67. Describe the internal structure of the kidney.
Internal structure of the kidney: The kidney is a bean-shaped structure. Internally, it is divided into an outer cortex and an inner medulla. The medulla is in the form of medullary pyramids. Medullary pyramids are projected into the calyces. The cortex which extends between the medullary pyramids is called columns of Bertini.
Q68. What is vasa recta? State its function.
Vasa recta is the minute vessel of the peritubular network which runs parallel to the loop of Henle. It maintains the concentration gradient in the medullary interstitium and helps to maintain the osmolarity of blood.
Q69. Name the network of the efferent arteriole formed around the renal tubule.
Q70. State the function of sebum.
The sebum provides a protective oily covering which protects the skin.
Q71. Explain the renin-angiotensin mechanism.
A fall in glomerular blood pressure activates the juxta glomerular cells to release renin. Renin converts angiotensin, first to angiotensin I and then to angiotensin II. Angiotensin II increases the glomerular blood pressure which increases the glomerular filtrate rate (GFR).
At the same time, angiotensin II activates the adrenal cortex to release aldosterone. Aldosterone stimulates the reabsorption of sodium ions and water from DCT. This also results in an increase in GFR.
Q72. State in one line as to what happens in following disorders: Renal calculi Glomerulonephritis
Renal calculi – An insoluble mass of crystals of oxalates is formed in the kidneys. Glomerulonephritis – Inflammation of glomeruli of the kidneys.
Q73. Name the cells which secrete K+ and H+ during urine formation.
Tubular cells secrete K+ and H+ during urine formation.