CBSE Class 11 Biology VBQs Excretory Products And Their Elimination

Question. Malpighian corpuscles occur in ______.
(a) medulla
(b) cortex
(c) pelvis
(d) pyramid

Answer. B

Question. A person has damaged renal tubules and produces scanty urine. He is not able to produce enough erythropoietin required for adequate RBC production and is thus suffering from anaemia. Identify the disorder from which he is suffering.
(a) Renal failure
(b) Diabetes insipidus
(c) Renal tubular acidosis
(d) Uremia

Answer. A

Question. Urine formed in man is
(a) hypotonic
(b) hypertonic
(c) isotonic
(d) alkaline. 

Answer. B

Question. Reabsorption of chloride ions (Cl–) from the glomerular filtrate, in the kidney tubule of mammal, is carried out by
(a) active transport
(b) diffusion
(c) osmosis
(d) brownian movement.

Answer. B

Question. Effective net filtration pressure in the glomerulus in kidney of man is about
(a) +75 mm Hg
(b) +80 mm Hg
(c) +20 to 25 mm Hg
(d) +50 mm Hg.

Answer. C

Question. Which one of the following operates Renin Angiotensin Aldosterone System (RAAS)?
(a) JGA
(b) Bowman’s capsule
(c) Loop of Henle
(d) ANF

Answer. A

Question. Sodium is reabsorbed in the collecting duct under the influence of
(a) antidiuretic hormone
(b) renin
(c) aldosterone
(d) both (a) and (b).

Answer. C

Question. In _____ water is reabsorbed due to increasing osmolarity of interstitial fluid.
(a) ascending limb of Henle’s Loop
(b) descending limb of Henle’s Loop
(c) collecting duct
(d) proximal convoluted tubule

Answer. B

Question. Match the column I with column II, and choose the correct combination from the options
given below.
Column I Column II
A. Water reabsorption I. Vasodilation
B. ANF II. Adrenal cortex
C. Angiotensin II III. ADH
(a) A-II, B-III, C-I
(b) A-I, B-III, C-II
(c) A-III, B-I, C-II
(d) A-I, B-II, C-III

Answer. C

Question. Kidney stones are produced due to deposition of ____ and ____.
(a) silicates, uric acid
(b) minerals, water
(c) silicates, calcium carbonate
(d) uric acid, calcium oxalate

Answer. D

Question. Which of the following statement is not scientifically correct?
(a) Left kidney is slightly higher than the right one.
(b) Columns of Bertini lie in between the pyramids.
(c) Renal vein contains more amount of excretory products than the renal artery.
(d) Hilum is the gateway for the kidney.

Answer. C

Question. Angiotensinogen is a protein produced and secreted by
(a) juxtaglomerular (JG) cells
(b) macula densa cells
(c) endothelial cells in the blood vessels
(d) liver cells.

Answer. D

Question. Select the group containing ammonotelic animals only.
(a) Earthworm, frog, turtle, pigeon
(b) Crocodile, earthworm, leech, bony fish
(c) Cockroach, land snail, prawn, toad
(d) Tapeworm, lizard, shark, leech

Answer. B

Case I : Read the following passage and answer questions from 41 to 45 given below.
Excretion is the process of expelling of nongaseous nitrogenous wastes like ammonia, urea, uric acid, etc, along with excess of water,salt s and pigments out of the body. Animals
maintain the ionic and acid-base balance of body by excreting wastes through organs like protonephridia, nephridia, malpighian tubules,green glands and kidneys. In humans, excretory system consist of one pair of kidneys, a pair of ureters, a urinary bladder and a urethra.

Question. Select the correct set of animals which excrete ammonia.
(a) Unio, Limnaea, Sycon
(b) Ascaris, Sycon, Asterias
(c) Leech, Pila, Helix
(d) Nereis, Prawn, Sycon

Answer. D

Question. Excretory structures present in Amphioxus is
(a) nephridia
(b) protonephridia
(c) Malpighian tubule
(d) green glands.

Answer. B

Question. Select the incorrect statement regarding male urethra.
(A) It is much longer.
(B) It is not differentiated into regions.
(C) It carries only urine.
(D) It opens out at the tip of penis by urinogenital aperture.
(a) A and C
(b) A and D
(c) B and C
(d) B and D

Answer. C

Question. Ureters, blood vessels, nerves enter or leave kidney through
(a) tubules
(b) nephrons
(c) hilus
(d) trigone.

Answer. C

Question. Ureters carry urine from
(a) urethra to urinary bladder
(b) kidneys to urinary bladder
(c) urinary bladder to urethra
(d) urethra to kidney.

Answer. B

Assertion & Reasoning Based MCQs

For question numbers 51-60, two statements are given-one labelled Assertion and the other labelled Reason.
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Assertion is false but reason is true.

Question. Assertion : When water has to be conserved in the body, ADH is released from the posterior pituitary.
Reason : ADH renders the walls of DCT and collecting duct and tubule impermeable to water.

Answer. C

Question. Assertion : Sharks are said to be ammonotelic animals.
Reason : Sharks can retain considerable amounts of urea in their blood.

Answer. D

Question. Assertion : Urinary bladder and ureters are lined by transitional epithelium.
Reason : Ureters carry the urine to urinary bladder where it is stored temporarily.

Answer. B

Question. Assertion : The glomerular filtrate resembles the protein free plasma in composition and osmotic pressure.
Reason : The glomerular capillary wall and inner membrane of Bowman’s capsule are impermeable to large molecules.

Answer. B

Question. Assertion : Kidneys maintain the osmotic concentration of the blood.
Reason : Kidneys eliminate either hypotonic or hypertonic urine according to the need of the body.

Answer. A

Very Short Answer Type Questions :

Question. What are green glands? Where are they found?

Answer. Green glands are structures involved in excretion. They are found in prawns (crustaceans).

Question. Identify the structures :
(a) Funnel shaped space inside the kidney
(b) Projections into medulla.

Answer. (a) Renal pelvis (b) Calyces 

Question. How much amount of blood is filtered by the kidneys per minute?

Answer. On an average, 1100 to 1200 mL of blood is filtered by the kidneys per minute.

Question. How is the back flow of urine into the ureters prevented?

Answer. The back flow of urine into the ureters is prevented because the terminal part of each ureter passes obliquely through the bladder wall and closed due to compression by the contracting bladder muscles.

Question. Why is glomerular filtration also known as ultrafiltration?

Answer. Ultrafiltration is filtration under pressure. Glomerular filtration is also called ultrafiltration due to the high blood pressure in the glomerular capillaries that allows continuous process of filtration through the semi-permeable glomerular capillaries.

Question. What are the two counter current systems that help in concentration of urine?

Answer. The two counter current systems are glomerular filtrate in the Henle’s loop and blood in the vasa recta that flow in opposite directions.

Short Answer Type Questions :

Question. Describe the structure of Malpighian corpuscle with the help of a neatly labelled diagram.

Answer. The diagram of Malpighian corpuscle is as follows: (IMG 157) The Malpighian Corpuscle (= Renal corpuscle; fig.): It comprises glomerulus and Bowman’s capsule. (i) Glomerulus : It is a tuft of capillaries. This capillary network consists of a complex anastomosing plexus of vessels and not of independent capillary loops. Blood enters the glomerulus through an afferent arteriole and leaves it through an efferent arteriole. Glomerular filtration takes place in the glomerulus. (IMG 157) (ii) Bowman’s Capsule (= Glomerular capsule) : It is a double layered cup-shaped structure. The lumen of the capsule is continuous with the narrow lumen of the renal tubule. The two layers of the Bowman’s capsule are outer parietal layer and inner visceral layer. The visceral layer surrounds the glomerulus and is composed of special type of cell, the podocytes.

Question. The blood vessels and nephrons of kidney are deeply associated with each other. Justify.

Answer. There is an intimate association between the blood vessels and the nephrons of the kidney. This association permits both extensive filtration from the blood and selective reabsorption back into the blood. After entering each kidney, the renal artery branches repeatedly, forming smaller and smaller arteries, until tiny arterioles reach each of the 1 million nephrons. An afferent arteriole delivers blood to the glomerulus for filtration, an efferent arterioles drains filtered blood away from the same glomerulus. The efferent arteriole connects to a second network of capillaries, the peritubular capillaries, which are closely associated with the nephron tubule. It is into these peritubular capillaries that water, ions and nutrients are reabsorbed from the filtrate in the nephron tubule. From the peritubular capillary network arise the capillaries of vasa recta, which extend parallel to the loops of Henle and the collecting ducts in the medulla. The vasa recta consist of descending capillaries and ascending capillaries. All the capillary networks join to form renal venules which join to form a renal vein that opens into the inferior vena cava.

Question. What are the various functions performed by human kidneys?'

Answer. The various functions of human kidney are : (i) Osmoregulation (ii) Elimination of nitrogenous wastes (iii) Maintenance of pH (iv) Maintenance of salt contents (v) Removal of other substances such as toxic substances, drugs, pigments, excess vitamins from the blood (vi) Maintenance of blood pressure (vii) Secretion of renin (viii) Erythropoietin production (ix) Homeostasis.

Question. What is the role of liver in excretion?

Answer. Urea is formed in the liver which is eliminated through kidneys. Liver cells also degrade the haemoglobin of worn out red blood corpuscles into bile pigments (bilirubin and biliverdin). Liver cells also excrete cholesterol, certain products of steroid hormones, some vitamins and many drugs. Liver secretes these substances in the bile. The bile carries these substances to the intestine and are passed out with faeces.

Question. If a person is passing out dilute urine and suffering from fever and back pain, what is the most probable reason for this?

Answer. The person is suffering from pyelonephritis. It is an inflammation of the renal pelvis and the medullary tissue of the kidney. This disease is usually caused by bacteria that reach the kidney by way of the urethra and ureter. It usually affects countercurrent mechanism in the medulla. Affected person has inability to concentrate his urine. Symptoms of this disease are frequent and painful urination, fever and back pain.

Question. Comment upon the hormonal regulation of selective reabsorption.

Answer. An excessive loss of fluid from the body can activate the osmoreceptors present in the body which further stimulate the hypothalamus to release antidiuretic hormone (ADH) from the neurohypophysis. ADH facilitates water reabsorption in distal convoluted tubule and collecting duct. An increase in body fluid volume can switch off the osmoreceptors and suppress the ADH release to complete the feedback. Angiotensin II also activates the adrenal cortex to release aldosterone. This hormone causes reabsorption of Na+ and water from the distal parts of the tubule.

Question. Draw a labelled diagram of human excretory system.

Answer. The diagram of human excretory system is as follows: (IMG 158)

Question. What are the factors that can affect the glomerular filtration rate (GFR)?

Answer.  The factors that can affect the glomerular filtration rate (GFR) are: (i) It increases with increase in renal blood flow. (ii) An increase in glomerular capillary hydrostatic pressure can increase glomerular filtration rate. (iii) Increase in systemic blood pressure can increase GFR. (iv) Increase in constriction of afferent and/or efferent arteriole increases GFR.

Long Answer Type Questions :

Question. A person has been suffering from acute renal failure.
(a) What is the most appropriate way of treating him?
(b) Diagrammatically represent the procedure of the treatment.

Answer. (a) When the kidneys are completely damaged and do not function, the patient often receives haemodialysis (treatment with an artificial kidney). Haemodialysis is the separation of certain substances from blood by use of a selectively permeable membrane. The pores in the membrane allow some substances to pass through, however, prevent others. The patient is connected to the machine by a tube attached to the radial artery. Blood from the artery is pumped into a tube that runs through the dialyzer. The dialyzer is filled with dialysis fluid which contains the same quantities of electolytes and nutrients as normal plasma but contains no waste products. The cellophane tube (a tube bounded by thin membrane) is kept in the dialysis fluid. The membrane of the cellophane tube is impermeable to blood cells and proteins but permeable to urea, uric acid, creatinine and mineral ions. So, these wastes diffuse from the blood to the dialysis fluid across the cellophane membrane. Thus, the blood is cleared of nitrogenous waste products without losing plasma proteins. Such a process of separating small solutes from macromolecular colloids with the help of a selectively permeable membrane is called dialysis. Now the blood is returned to the patient’s body through a vein usually the radial vein. Haemodialysis saves and prolongs the life of many patients. (b) A schematic diagram to show the working of an artificial kidney is : (IMG 160)

Question. List the different parts of the nephron’s renal tubule along with their internal features.

Answer.  The renal tubule consists of the following parts: (i) Proximal convoluted tubule (PCT): The Bowman’s capsule leads into the proximal convoluted tubule that is lined by cuboidal epithelium which has a brush border of microvilli at the free end for increasing the surface area. The basolateral surface of these cells have number of mitochondria for the reabsorption of salts by active transport. (ii) Loop of Henle : It starts from the PCT with its major part in the medulla. It has an ascending and a descending limb. The descending limb is continuous with the PCT having the upper part with the same diameter but as it descends further, it narrows down. The upper part has cuboidal epithelium but the cells have less microvilli and mitochondria as compared to PCT. The narrow segment also called the thin segment has flat epithelial cells with thinly scattered microvilli and very few mitochondria. The ascending limb also has thick and thin segments. The thick segment of ascending limb is lined by cuboidal epithelial cells with short apical microvilli and numerous mitochondria. (iii) Distal convoluted tubule (DCT) : The thick segment of ascending limb of loop of Henle is continuous with the DCT that lies in the cortex. It is lined by cuboidal cells that have few, small and irregularly spaced microvilli. The distal convoluted tubule joins the collecting duct on the other hand.