Case Study Questions Class 11 Biology Excretory Products and their Elimination

Case Study Questions Class 11 Biology Chapter 19 Excretory Products and their Elimination

CBSE Class 11 Case Study Questions Biology Excretory Products and their Elimination. Important Case Study Questions for Class 11 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Excretory Products and their Elimination.

At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.

CBSE Case Study Questions Class 11 Biology Excretory Products and their Elimination

CASE 1

Urine formation involves three main processes namely, glomerular filtration, reabsorption and secretion, that takes place in different parts of the nephron. The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and is called glomerular filtration. On an average, 1100-1200 ml of blood is filtered per minute. The glomerular capillary blood pressure causes filtration of blood through 3 layers, i.e., the endothelium of glomerular blood vessels, the epithelium of Bowman’s capsule and a basement membrane between these two layers. The epithelial cells of Bowman’s capsule called podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores. 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.

The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day!

The kidneys have built-in mechanisms for the regulation of glomerular filtration rate. One such efficient mechanism is carried out by juxta glomerular apparatus (JGA). JGA is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arteriole at the location of their contact. A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.

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. The tubular epithelial cells in different segments of nephron perform this either by active or passive mechanisms. For example, substances like glucose, amino acids, Na+ , etc., in the filtrate are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport. Reabsorption of water also occurs passively in the initial segments of the nephron. During urine formation, the tubular cells secrete substances like H+, K+ and ammonia into the filtrate. Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid base balance of body fluids.

1.) Identify the correct statement

Statement 1 – Tubular epithelial cells perform reabsorption either by active or passive mechanisms.

Statement 2 – Amount of the filtrate formed by the kidneys per minute is glomerular filtration rate.

Statement 3 – The first step in urine formation is the filtration of blood.

Statement 4 – Renin can stimulate the glomerular blood flow.

 

a) Both 1 & 2

b) Only 2

c) Both 3 & 4

d) All of the above

2.) ______________ stimulate the glomerular blood flow.

a) Tubular secretion

b) Renin

c) renal tubules

d) podocytes

3.) What is the main function of tubular epithelial cells?

4.) How filtration slits are formed?

5.) What is the role of Tubular secretion during urine formation?

Answer key

1.) d

2.) b

3.) The tubular epithelial cells in different segments of nephron perform reabsorption either by active or passive mechanisms.Substances like glucose, amino acids, Na+, etc., in the filtrate are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport.

4.) The epithelial cells of Bowman’s capsule are arranged in an intricate manner that they small minute space like pores, these pores are called filtration slits or slit pores.

5.) Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid base balance of body fluids.

CASE 2

Animals accumulate ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl–, phosphate, sulphate, etc., either by metabolic activities or by other means like excess ingestion. These substances have to be removed totally or partially. Ammonia, urea and uric acid are the major forms of nitrogenous wastes excreted by the animals. Ammonia is the most toxic form and requires large amount of water for its elimination, whereas uric acid, being the least toxic, can be removed with a minimum loss of water.

The process of excreting ammonia is Ammonotelism. Many bony fishes, aquatic amphibians and aquatic insects are ammonotelic in nature. Ammonia, as it is readily soluble, is generally excreted by diffusion across body surfaces or through gill surfaces (in fish) as ammonium ions. Kidneys do not play any significant role in its removal. Terrestrial adaptation necessitated the production of lesser toxic nitrogenous wastes like urea and uric acid for conservation of water. Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals. Ammonia produced by metabolism is converted into urea in the liver of these animals and released into the blood which is filtered and excreted out by the kidneys. Some amount of urea may be retained in the kidney matrix of some of these animals to maintain a desired osmolarity. Reptiles, birds, land snails and insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.

A survey of animal kingdom presents a variety of excretory structures. In most of the invertebrates, these structures are simple tubular forms whereas vertebrates have complex tubular organs called kidneys. Some of these structures are mentioned here. Protonephridia or flame cells are the excretory structures in Platyhelminthes (Flatworms, e.g., Planaria), rotifers, some annelids and the cephalochordate – Amphioxus. Protonephridia are primarily concerned with ionic and fluid volume regulation, i.e., osmoregulation. Nephridia are the tubular excretory structures of earthworms and other annelids. Nephridia help to remove nitrogenous wastes and maintain a fluid and ionic balance. Malpighian tubules are the excretory structures of most of the insects including cockroaches. Malpighian tubules help in the removal of nitrogenous wastes and osmoregulation. Antennal glands or green glands perform the excretory function in crustaceans like prawns.

1.) Identify the correct function of Nephridia

a.) help to remove nitrogenous wastes

b) help to maintain a fluid

c) help toionic balance

d.) all of the above

2.) Identify the correct statement from given below

Statement 1 – Uric acid can be eliminated with minimum loss of water.

Statement 2 – Ammonia requires large amount of water for its elimination.

Statement 3 – The process of eliminating ammonia is named as Ammonotelism.

Statement 4 – Animals which excrete urea are called ureotelic animals

 

a) Statement 1 & 2 are correct

b) Statement 2 & 4 are correct

c) Statement 3 & 4 are correct

d) All of the abovestatement are correct

3) Name the excretory structure found in Platyhelminthes.

4) Explain the role of terrestrial adaption in excretion.

5) Name the excretory structure present in the crustaceans, insects and earthworms.

Answer key

1.) d

2.) d

3.) Protonephridia or flame cells are the excretory structures in Platyhelminthes.

4.) Terrestrial adaptation necessitated the production of lesser toxic nitrogenous wastes like urea and uric acid for conservation of water.

5.) Excretory structure present in the crustaceans, insects and earthworms.

  • Crustaceans – Antennal glands or green glands perform the excretory function in crustaceans.
  • Insects – Malpighian tubules are the excretory structures of most of the insects.
  • Earthworms – Nephridia are the tubular excretory structures of earthworms

CASE 3

In humans, the excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder and a urethra. Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity. Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120- 170 g. towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter. Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces. The outer layer of kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex and an inner medulla. The medulla is divided into a few conical masses (medullary pyramids) projecting into the calyces. The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini.

Each kidney has nearly one million complex tubular structures called nephrons, which are the functional units. Each nephron has two parts – the glomerulus and the renal tubule. Glomerulus is a tuft of capillaries formed by the afferent arteriole – a fine branch of renal artery. Blood from the glomerulus is carried away by an efferent arteriole.

The renal tubule begins with a double walled cup-like structure called Bowman’s capsule, which encloses the glomerulus. Glomerulus alongwith Bowman’s capsule, is called the Malpighian body or renal corpuscle. The tubule continues further to form a highly coiled network – proximal convoluted tubule (PCT). A hairpin shaped Henle’s loop is the next part of the tubule which has a descending and an ascending limb. The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT). The DCTs of many nephrons open into a straight tube called collecting duct, many of which converge and open into the renal pelvis through medullary pyramids in the calyces.

The Malpighian corpuscle, PCT and DCT of the nephron are situated in the cortical region of the kidney whereas the loop of Henle dips into the medulla. In majority of nephrons, the loop of Henle is too short and extends only very little into the medulla. Such nephrons are called cortical nephrons. In some of the nephrons, the loop of Henle is very long and runs deep into the medulla. These nephrons are called juxta medullary nephrons.

The efferent arteriole emerging from the glomerulus forms a fine capillary network around the renal tubule called the peritubular capillaries. A minute vessel of this network runs parallel to the Henle’s loop forming a ‘U’ shaped vasa recta. Vasa recta is absent or highly reduced in cortical nephrons.

1.) Inner side to the hilum is a broad funnel shaped cavity space is present, is known as___________

a) Renal pelvic

b) Renal pelvis

c) Renal tubule

2.) Blood from turf of capillaries is carried away by ____________

a) Afferent arteriole

b) Branch of renal artery

c) Efferent arteriole

d) None of the above

3.) How Glomerulus formed?

4.) What is cortical nephrons?

5.) What is juxta medullary nephrons?

6.) Explain what is mean by peritubular capillaries?

Answer key

1.) b

2.) c

3.) Glomerulus is a tuft of capillaries. Glomerulus are formed by a very fine branch of renal artery i.e. afferent arteriole.

4.) Nephrons in which the loop of Henle is too short and extends only very little into the medulla, such nephron are named as cortical nephrons.

5.) Nephrons in which the loop of Henle is very long and runs deep into the medulla. These nephrons are called juxta medullary nephrons.

6) The efferent arteriole arising from the glomerulus forms a fine capillary network around the renal tubule, is named as the peritubular capillaries.

CASE 4

Malfunctioning of kidneys can lead to accumulation of urea in blood, a condition called uremia, which is highly harmful and may lead to kidney failure. In such patients, urea can be removed by a process called hemodialysis. During the process of haemodialysis, the blood drained from a convenient artery is pumped into a dialysing unit called artificial kidney. Blood drained from a convenient artery is pumped into a dialysing unit after adding an anticoagulant like heparin. The unit contains a coiled cellophane tube surrounded by a fluid (dialysing fluid) having the same composition as that of plasma except the nitrogenous wastes. The porous cellophane membrance of the tube allows the passage of molecules based on concentration gradient. As nitrogenous wastes are absent in the dialysing fluid, these substances freely move out, thereby clearing the blood. The cleared blood is pumped back to the body through a vein after adding anti-heparin to it. This method is a boon for thousands of uremic patients all over the world.

Kidney transplantation is the ultimate method in the correction of acute renal failures (kidney failure). A functioning kidney is used in transplantation from a donor, preferably a close relative, to minimise its chances of rejection by the immune system of the host. Modern clinical procedures have increased the success rate of such a complicated technique.

Renal calculi is Stone or insoluble mass of crystallised salts (oxalates, etc.) formed within the kidney. Glomerulonephritis is Inflammation of glomeruli of kidney.

1.) During the process dialysis, when the cleared blood is pumped back to the body which of the following factor is added to it

a) Coagulant

b) Heparin

c) Anti-heparin

d) None of the above

2.) Glomerulonephritis is characterized by ______________________

a) Inflammation of kidney

b) accumulation of urea in blood

c) kidney stone

d) Pyelonephritis

3.) Name a condition in which crystallised salts are present in kidney?

4.) What is mean by uremia?

5.) What is heparin?Explain its use?

Answer key

1.) c

2.) a

3.) A condition in which crystallised salts or insoluble mass are present in kidney is referred as renal calculi. It is also known as kidney stone.

4.) When kidneys doesn’t functions properly it can leads to accumulation of urea in blood. Such condition of accumulation of urea in blood are is called as uremia, which is highly harmful and may lead to kidney failure.

5.) Heparin is an anticoagulant. It is used in process of hemodialysis. When blood drained from a convenient artery is pumped into a dialysing unit after adding Heparin.

CASE 5

Proximal Convoluted Tubule (PCT) – PCT is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients, and 70-80 per cent of electrolytes and water are reabsorbed by this segment. PCT also helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO3 – from it.

Henle’s Loop – Reabsorption is minimum in its ascending limb. However, this region plays a significant role in the maintenance of high osmolarity of medullary interstitial fluid. The descending limb of loop of Henle is permeable to water but almost impermeable to electrolytes. This concentrates the filtrate as it moves down. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. Therefore, as the concentrated filtrate pass upward, it gets diluted due to the passage of electrolytes to the medullary fluid.

Distal Convoluted Tubule (DCT) – Conditional reabsorption of Na+ and water takes place in this segment. DCT is also capable of reabsorption of HCO3 – and selective secretion of hydrogen and potassium ions and NH3 to maintain the pH and sodium-potassium balance in blood.

Collecting Duct – This long duct extends from the cortex of the kidney to the inner parts of the medulla. Large amounts of water could be reabsorbed from this region to produce a concentrated urine. This segment allows passage of small amounts of urea into the medullary interstitium to keep up the osmolarity. It also plays a role in the maintenance of pH and ionic balance of blood by the selective secretion of H+ and K+ ions.

1.) Proximal Convoluted Tubule is surrounded by________________

a) Brush border columnar cells

b) Brush border cuboidal cells

c) Ciliated cuboidal cells

d) Ciliated columnar cells

2.) Tubular secretion of hydrogen and potassium occurs in

a) Henle’s Loop

b) Proximal Convoluted Tubule

c) Distal Convoluted Tubule

d) Both b and c

3.) Explain how ascending limb of Henle loop functions when filtrate passes through it?

4.) Name the segment of tubule in which reabsorption is minimum.

5.) What is major difference between ascending and descending alimbs of Henle’s Loop?

Answer key

1.) b

2.) d

3.) The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. As the ascending limb is impermeable to water, therefore as the concentrated filtrate from the descending limb passes upwards, then it gets diluted due to the passage of electrolytes to the medullary fluid.

4.) Reabsorption is minimum in Henle’s Loop, specifically in ascending limb of Henle’s Loop.

5) The descending limb of loop of Henle is permeable to water but almost impermeable to electrolytes.

The ascending limb is impermeable to water but allows transport of electrolytes actively or passively.

Updated: April 5, 2022 — 1:39 am

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