Excretory Products and Their Elimination Class 11 Biology Exam Questions

Please refer to Excretory Products and Their Elimination Class 11 Biology Exam Questions provided below. These questions and answers for Class 11 Biology have been designed based on the past trend of questions and important topics in your class 11 Biology books. You should go through all Class 11 Biology Important Questions provided by our teachers which will help you to get more marks in upcoming exams.

Class 11 Biology Exam Questions Excretory Products and Their Elimination

Class 11 Biology students should read and understand the important questions and answers provided below for Excretory Products and Their Elimination which will help them to understand all important and difficult topics.

Very Short Answer Type Questions:

Question. What is the composition of sweat produced by sweat glands?
Ans. Sweat produced by sweat glands is a watery fluid containing NaCl, small amounts of urea, lactic acid, etc. Its primary function is to facilitate a cooling effect on the body surface and also to helps in removal of waste.

Question. Fill in the blanks appropriately Organ Excretory wastes
(a) Kidneys …………………
(b) Lungs …………………
(c) Liver …………………
(d) Skin …………………
Ans. Organ Excretory wastes
(a) Kidneys Urine
(b) Lungs CO2
(c) Liver Urea
(d) Skin Sweat

Question. Differentiate glycosuria from ketonuria.
Ans. Difference between glycosuria and ketonuria is as follows

Question. Identify the glands that perform the excretory function in prawns.
Ans. In prawns, the excretory organs are known as antennary glands or green glands. These glands are opaque-white pea sized structures, enclosed in the coxa of each 2nd antenna.
They mainly excrete ammonia.

Question. What is the excretory structure in Amoeba?
Ans. Contractile vacuole is the excretory organ in Amoeba. It is also involved in osmoregulation.

Question. What is the excretory product from kidneys of reptiles?
Ans. Reptiles excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.

Question. What are the main processes of urine formation?
Ans. Urine formation includes glomerular filteration (ultra filteration), selective reabsorption and tubular secretion that takes place in different parts of the nephron.
Glomerular filteration involves the filteration of blood, which is carried out by glomerulus.
Selective reabsorption is the absorption of filtrate through renal tubules either actively or passively.
Tubular secretion involves secretion through tubular cells in urine in order to maintain ionic and acid-base balance of body fluids.

Question. The following abbreviations are used in the context of excretory functions, what do they stand for?
(a) ANF (b) ADH
(b) GFR (d) DCT
Ans. (a) ANF Atrial Natriuretic Factor
(b) ADH Antidiuretic Hormone
(c) GFR Glomerular Filteration Rate
(d) DCT Distal Convoluted Tubule

Question. Mention the substances that exit from the tubules in order to maintain a concentration gradient in the medullary interstitium.
Ans. The concentration gradient in medullary interstitium is established primarily by renal tubules of loop of Henle and the blood vessels surrounding them (vasa recta) in a process called countercurrent exchange.
The substances that exit from tubules for maintenance of such gradient are mainly sodium chloride (NaCl), water and urea (contaning H⁺ , K⁺ and NH⁺3 ).

Question. What is the role of sebaceous glands?
Ans. Sebaceous glands are involved in the elimination of certain substances like cholesterol, squalene, triglycerides wax and esetrs through sebum. This secretion provides oily covering to the skin.

Question. Name two actively transported substances in glomerular filtrate.
Ans. The substances that are actively transported in the glomerular filtrate are glucose and amino acids.

Question. Mention any two metabolic disorders, which can be diagnosed by analysis of urine.
Ans. Metabolic disorders that can be diagnosed by analysis of urine are
(i) Hematuria It is the presence of blood or blood cells in the urine, which could be a sign of kidney stone or a tumor in urinary tract.
(ii) Albuminuria It is the presence of albumin in urine and occurs in nephritis i e . ., inflammation of glomeruli. In this condition the size of filtering slits becomes enlarged.

Question. Where does the selective reabsorption of glomerular filtrate take place?
Ans. The selective reabsorption of glomerular filtrate takes place in Proximal Convoluted Tubules (PCT) and Distal Convoluted Tubules (DCT).
In PCT all essential elements nutrients, 70-80% of electrolytes and water is absorbed whereas, Distal Convoluted Tubule (DCT) is involved in conditional reabsorption of Na + and water.

Question. Sort the following into actively or passively transported substances during reabsorption of GFR. e.g., glucose, amino acids, nitrogenous wastes, Na+, water.
Ans.Actively transported substances during reabsorption of GFR- Glucose, amino acids, Na⁺.
Passively transported substances during reabsorption of GFR− Nitrogenous wastes, water.

Question. Complete the following
(a) Urinary excretion = tubular reabsorption + tubular secretion −
(b) Dialysis fluid = plasma −
Ans. (a) Urinary excretion = tubular reabsorption + tubular secretion − filtration
(b) Dialysis fluid = plasma − nitrogenous wastes.

Short Answer Type Questions:

Question. Aquatic animals generally are ammonotelic in nature where as terrestrial forms are not. Comment.
Ans. The process of excreting ammonia is called ammonotelism. many bony fishes, aquatic amphibians and aquatic insects are ammonotelic in nature. Ammonia, as its readily soluble, in water is excreted by diffusion across body surface or through gill surfaces (in fishes) as ammonium ions.
It is highly soluble in water and requires large amounts of water to be lost from the body.
Such a mode of excretion is thus suitable for aquatic organisms which have a constant access to water.
Terrestrial adaptation requires the production of lesser toxic nitrogenous wastes like urea, as urea is less toxic and less soluble in water. This is important adaptation for water conservation in animals body. Mammals, many terrestrial amphibians and marine fishes mainly excrete urea and are called ureotelic animals.
In most insects land snails, reptiles etc., uric acid is excreted, hence they are called uricotelic animals. Conversion of ammonia to uric acid and its elimination requires less water, thus it is very essential for terrestrial forms that do not have constant water supply.

Question. Label the parts in the following figure.

Ans. The labelling part of the given figure are as listed

Question. The composition of glomerular filtrate and urine is not same. Comment.
Ans. The composition of glomerular filtrate and urine is not the same as the glomerular filtrate contains a large amount of water and other dissolved substances such as urea, uric acid, creatinine, amino-acid, glucose, sodium, potassium vitamins, etc.
Urine on the other hand is a transparent, light yellow fluid, which is formed after rigrous reabsorption and secretion from the filterate. It constitute about 95% water and 5% of other organic and inorganic substances.
Organic substances in urine includes nitrogen, urea, creatine, ammonia uric acid, oxalic acid, vitamins, hormones and enzymes.
Whereas inorganic substance in urine include chloride, phosphate, sulphate, potassium, sodium, calcium, magnesium, iodine, arsenic and lead. Glucose is not found in urine normally. Hence, composition of glomerular filtrate and urine is different.

Question. Show the structure of a renal corpuscle with the help of a diagram.
Ans. Representing the structure of a renal corpuscle

Question. How have the terrestrial organisms adapted themselves for conservation of water?
Ans. Terrestrial adaptation necessitated the production of lesser toxic nitrogenous wastes like urea and uric acid for the conservation of water. Mammals and many terrestrial amphibians mainly excrete urea and are called uriotelic 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 urea is retained in kidney in order to maintain osmolarity, reptilelos birds, land snails and insects excrete nitrogeneous waste, as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals. Conversion of ammomia to uric acid and its subsequent elimination requires lesser amount of water.
Hence, due to less availability of water on land, and in order to minimise water loss, terrestrial organism adapted themselves accordingly.

Question. Comment upon the hormonal regulation of selective reabsorption.
Ans. The functioning of the kidneys is efficiently monitored and regulated by Antidiuretic Hormone (ADH), Juxtaglomerular Apparatus (JGA) and Atrial Natriuretic Factor (ANF).
(a) Antidiuretic Hormone (ADH) or vasopressin from the neurohypophysis, facilitates water reabsorption from latter parts of tubule, i.e., distal convoluted tubule and collecting duct by increasing the permeability to water and salt and by accelerating water and ion transfer in a direction determined by the osmotic gradient.
(b) Juxta Glomerular Apparatus (JGA) operates a multihormonal. Renin Angiotensin Aldosterone System (RAAS). JG cells secrete an enzyme, renin, which, changes plasma protein called angiotensinogen to a peptide called angiotensin I and further to angiotensin II, which works as a hormone.
Angiotensin II, being a powerful vasoconstrictor increases the glomerular blood pressure and thereby GFR. It also stimulate’s soduim absorption by proximal tubules.
(c) Angiotensin II also activates the adrenal cortex to release aldosterone. Aldosterone induces the distal convoluted tubule to absorb more Na + and water.
(d) Atrial Natriuretic Factor (ANF) is produced by the atria of heart. It regulates blood flow by causing vasodilation and increasing sodium excretion. It is also involved in checking of renin-angiotensin mechanism.

Question. What is the role played by renin-angiotensin in the regulation of kidney function?
Ans. Renin is released from the Juxta-Glomerular Apparatus (JGA) on activation by fall in the glomerular blood pressure/flow. Renin 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 Glomerular Filteration Rate (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. This also, leads to an increase in blood pressure and GFR. This complex mechanism is generally known as Renin Angiotensin Aldosterone System or RAAS.

Question. Explain, why a haemodialysing unit called artificial kidney?
Ans. Haemodialysis This method is a boon for thousands of uremic (accumulation of urea in blood) patients all over the world.
Haemodialysing unit act an on artificial kidney by removing urea from patients blood due to kidney failure. In this process blood is drained from artery an pumped into a dialysing unit after the addition of an anticoagulant like heparin.
The unit contains a coiled cellophane tube surrounded by a dialysing fluid having the same composition as that of plasma except nitrogenous waste. The porous cellophane membrane of the tube allows the passage of molecules based on concentration gradient.
Due to the absence of nitrogenous wastes in dialysing fluid these substances freely move out, thereby clearing the blood.
In the end the cleared blood is pumped back to the body through a vein after the addition of anti-heparin to it thereby completing the process.

Question. What is the procedure advised for the correction of extreme renal failure?
Give a brief account of it.
Ans. Kidney transplantation is the ultimate method for the correction of acute/extreme renal failure (kidney failure). A functional kidney is used as a transplant 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.

Long Answer Type Questions:

Question. Explain briefly, micturition and disorders of the excretory system.
Ans. The process of release of urine is called micturition and the neural mechanism. causing it is called the micturition reflex.
The urinary bladder and the internal sphincter are supplied by sympathetic and parasympathetic nervous systems of autonomic nervous system. In response, the stretch receptors on the walls of the bladder send signals to the Central Nervous System (CNS).
The CNS passes on motor messages to initiate the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.
Disorders of excretory system includes
(i) Uremia It is the malfunctioning of kidneys, which leads to accumulation of urea in blood in turn the kidney faliure. In such patients urea can be removed by haemodialysis.
(ii) Renal Failure (RF) It is caused by a decrease in glomerular filteration. In Acute Renal Failure (ARF) both kidneys abruptly stop working due to damaged renal tubules, kidney stones, antibiotics, etc. Haemodialysis and renal transplant are the only ways to auruve overcome renal failure.
(iii) Renal Calculi It is the formation of stones or insoluble mass of crystallised salts in the kidney.
(iv) Glomerulonephritis It is the inflammation of glomeruli of kidney.

Question. Draw a labelled diagram showing reabsorption and secretion of major substances at different parts of the nephron.
Ans. A diagram showing reabsorption and secretion of major substances at different parts of the nephron are as follows

Question. Describe the structure of a human kidney with the help of a labelled diagram.
Ans.Human kidney are reddish-brown, bean-shaped structures situated between the 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 gm.
The kidney is covered by a fibrous connective tissue, the renal capsula, which protect the kidney. Internally, it consists of outer dark cortex and an inner light medulla, both containing nephron (structural and functional units of kidney.
The median conconcave border of a kidney contains a notch called hilum. Through which ureter blood vessels and urinitus.
The renal cortex is granular in apperance and contains convoluted tubules and Malpighian corpuscles. The renal medulla contains loop of Henle, collecting ducts and tubules and ducts of Bellini.
Medulla is divided into conical masses, the medullary pyramids which further form papillae.The papillae form calyces, which join to renal pelvis leading to ureter. Between the medullary pyramids, cortex extends into medulla and forms renal columns which are called as column of Bertini.

Question. How does tubular secretion help in maintaining ionic and acid-base balance in body-fluids?
Ans. In addition to the role of Proximal Convoluted Tublues (PCT) in selective reabsorption of materials from the glomerular filtrate back into the blood of peritubular capillaries via the renal interstitium, they also alter the composition of filtrate by the process of secretion.
In its distal part, epithelial cells extract certain excretory substances from the blood of peritubular capillaries and secrete these into the filtrate.
Creatinine, hippuric acid, pigments, drugs including penicillin are actively secreted into the filtrate in the proximal convolued tubule from the interstitial fluid. Hydrogen ions and ammonia are also secreted into the proximal convoluted tubules.
Urea enters the filtrate via diffusion in the thin segment of ascending limb of Henle’s loop.
Maximum hydrogen secretion occurs in the proximal convoluted tubules. Removal of hydrogen ion and NH3 from the blood in the PCT and Distal Convoluted Tubule (DCT) helps in maintaining pH of the blood, i.e., between 6 to 8.
Tubular secretion although possess a minor role in functioning of the human kidney, but plays an essential role in animals like marine fishes and desert amphibians, because these animal do not possess well developed glomeruli hence their urine is mainly formed by the tubular secretion of urea, creatinine and mineral ions.

Question. The glomerular filtrate in the loop of Henle gets concentrated in the descending and then gets diluted in the ascending limbs. Explain.
Ans. The glomerular filtrate in the loop of Henle gets concentrated in the descending loop and then gets diluted in the ascending limb. The thin wall of descending limb of Henle’s loop is permeable to water, but not to the solutes. The isotonic tubular fluid flows down the limb.
It gradually looses its water the by exosmosis due to increasing osmolarity of medullary interstitium through which the limb extends.
Thus, the filtrate becomes hypertonic to blood plasma. The ascending limb of loop of Henle is impermeable to water, but permeable to ions like K⁺ , Cl⁻, Na+ and it is partially permeable to urea.
Thus, in the thick ascending limb of the loop of Henle, Na, K, Ca, Mg and Cl are reabsorbed, making the filtrate hypotonic to blood plasma and diluted as compared to descending limb.

Question. Explain the mechanism of formation of concentrated urine in mammals.
Ans. Mammals have the ability to produce concentrated urine. The loop of Henle and vasa recta play a significant role in it, which can be discussed as follows
(i) The proximity between the Henle’s loop and vasa recta, as well as the counter current (formed due to the flow of filtrate in two limb’s of Henle’s loop in opposite direction) help
in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmoL−1 in the cortex to about 1200 mOsmoL⁻¹ in the inner medulla.

(ii) This gradient is caused mainly due to NaCl and urea. NaCl is transported by the ascending limb of Henle’s loop, which is exchanged with the descending limb of vasa recta.
(iii) NaCl is returned to the interstitium by the ascending portion of vasa recta.
(iv) Similarly, a small amount of urea enters the thin segment of the ascending limb of Henle’s loop, which is transported back to the interstitium by the collecting tubule.
(v) This special arrangement of Henle’s loop, and vasa recta, is called the counter current mechanism.
(vi) The counter current exchange reduces the rate of dissipation. This, inturn reduces the rate at which the current must pump Na⁺ to maintain any given gradient.
(vii) Presence of such interstitial gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine).
(viii) Human kidneys can produce urine nearly four times concentrated than the initial filtrate formed.