Important Questions Class 11 Biology Chapter 16 Excretory Products and their Elimination

Important Questions Class 11 Biology Chapter 16 Excretory Products and their Elimination

Excretory Products and their Elimination is Chapter 16 of Class 11 Biology. Excretion is the removal of harmful waste materials, such as ammonia, urea and uric acid, from the body. The chapter explains the human excretory system, the structure of the kidney and the nephron (the working unit of the kidney), how urine is formed, the role of hormones such as ADH (antidiuretic hormone), micturition and disorders of the excretory system.

This page gives 12 important questions from Excretory Products and their Elimination with clear answers prepared by Extramarks experts. The questions cover the diagram of the excretory system, the regions of a nephron, the juxta glomerular apparatus (JGA), osmoregulation, ureotelic and uricotelic animals, diabetes insipidus and micturition. Students can use them for school tests and CBSE (Central Board of Secondary Education) exam revision, and teachers and parents can use them for quick practice.

Important Questions Class 11 Biology Chapter 16 Excretory Products and their Elimination

Excretory Products and Their Elimination
Easy
Q.
Define Glomerular Filtration Rate (GFR).
Excretory Products and Their Elimination
Medium
Q.
Explain the autoregulatory mechanism of GFR.
Excretory Products and Their Elimination
Easy
Q.
Indicate whether the following statements are true or false:
(a) Micturition is carried out by a reflex.
(b) ADH helps in water elimination, making the urine hypotonic.
(c) Protein-free fluid is filtered from blood plasma into the Bowman’s capsule.
(d) Henle’s loop plays an important role in concentrating the urine.
(e) Glucose is actively reabsorbed in the proximal convoluted tubule.
Excretory Products and Their Elimination
Difficult
Q.
Give a brief account of the counter current mechanism.
Excretory Products and Their Elimination
Medium
Q.
Describe the role of liver, lungs and skin in excretion.
Excretory Products and Their Elimination
Easy
Q.
Explain micturition.
Excretory Products and Their Elimination
Medium
Q.
Match the items of column I with those of column II:
Column IColumn II(a) Ammonotelism(i) Birds(b) Bowman’s capsule(ii) Water reabsorption(c) Micturition(iii) Bony fish(d) Uricotelism(iv) Urinary bladder(e) ADH(v) Renal tubule\begin{array}{|l|l|} \hline \textbf{Column I}\rule[-2ex]{0pt}{5ex} & \textbf{Column II} \\\hline \text{(a) Ammonotelism} \rule[-2ex]{0pt}{5ex}& \text{(i) Birds} \\ \hline \text{(b) Bowman's capsule} &\rule[-2ex]{0pt}{5ex} \text{(ii) Water reabsorption} \\ \hline \text{(c) Micturition} \rule[-2ex]{0pt}{5ex}& \text{(iii) Bony fish} \\ \hline \text{(d) Uricotelism} \rule[-2ex]{0pt}{5ex}& \text{(iv) Urinary bladder} \\ \hline \text{(e) ADH} \rule[-2ex]{0pt}{5ex}& \text{(v) Renal tubule} \\\hline \end{array}
Excretory Products and Their Elimination
Easy
Q.
What is meant by the term osmoregulation?
Excretory Products and Their Elimination
Easy
Q.
Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic. Why?
Excretory Products and Their Elimination
Difficult
Q.
What is the significance of juxta glomerular apparatus (JGA) in kidney function?
Excretory Products and Their Elimination
Medium
Q.
Name the following:
(a) A chordate animal having flame cells as excretory structures
(b) Cortical portions projecting between the medullary pyramids in the human kidney
(c) A loop of capillary running parallel to Henle’s loop
Excretory Products and Their Elimination
Easy
Q.
Fill in the gaps:
(a) Ascending limb of Henle’s loop is _______ to water whereas the descending limb is _______ to it.
(b) Reabsorption of water from distal parts of the tubules is facilitated by hormone _______.
(c) Dialysis fluid contains all the constituents as in plasma except _______.
(d) A healthy adult human excretes (on an average) _______ gm of urea/day.

Q1. Draw a well-labelled diagram of human excretory system.

Answer: The excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder and a urethra.

Well-labelled diagram of the human excretory system

Q2. A nephron is differentiated into four major regions. Describe all the regions of a nephron.

Answer: A nephron is a complex tubular structure differentiated into four regions having different anatomical features and physiological role; Bowman’s capsule, Proximal Convoluted Tubule (PCT), Henle’s loop and Distal Convoluted Tubule (DCT).

(i) Bowman’s capsule - The Bowman’s capsule forms the beginning of the nephron and lies in the renal cortex. It is a large, double walled cup- like structure which encloses the glomerulus. Glomerulus along with Bowman’s capsule, is called the malpighian body or renal corpuscle.

(ii) Proximal Convoluted Tubule (PCT) - The tubule continues further to form a highly coiled network proximal convoluted tubule (PCT). Its wall consists of a single layer of columnar cells bearing microvilli on the free surface and resting on a basement membrane.

(iii) Henle’s loop – A U-shaped segment Henle’s loop is the next part of the tubule lies in the renal medulla. It consists of two parallel limbs: a descending and an ascending limb. Each limb has a thick region toward the cortex and a thin region on the other side.

(iv) Distal Convoluted Tubule (DCT) – The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT). A short terminal relatively straight part of the DCT is called collecting tubule. The latter opens into a collecting duct.

Q3. Describe the structure of a nephron in detail.

Answer: A nephron is a complex tubular structure differentiated into four regions having different anatomical features and physiological role; Bowman’s capsule, Proximal Convoluted Tubule (PCT), Henle’s loop and Distal Convoluted Tubule (DCT).

(i) Bowman’s capsule - The Bowman’s capsule forms the beginning of the nephron and lies in the renal cortex. The Bowman’s capsule is a large, double walled cup-like structure which encloses the glomerulus; its inner wall is called the visceral wall. Glomerulus along with Bowman’s capsule, is called the malpighian body or renal corpuscle.

(ii) Proximal Convoluted Tubule (PCT) - The tubule continues further to form a highly coiled network proximal convoluted tubule (PCT). Its wall consists of a single layer of columnar cells bearing microvilli on the free surface and resting on a basement membrane.

(iii) Henle’s loop – A U-shaped segment Henle’s loop is the next part of the tubule lies in the renal medulla. It consists of two parallel limbs: a descending and an ascending limb. Each limb has a thick region toward the cortex and a thin region on the other side.

(iv) Distal Convoluted Tubule (DCT) – The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT). A short terminal relatively straight part of the DCT is called collecting tubule. The latter opens into a collecting duct.

Q4. Diabetes insipidus is a condition which is characterised by excessive thirst and frequent urination. Which hormone is
responsible for these effects? Also, state the causes of diabetes insipidus.

Answer: Imbalance of ADH hormone is responsible for these effects.

Causes of diabetes insipidus are:

i. Normal storage and release of ADH from the posterior pituitary get disturbed.

ii. Inability of the kidneys to respond towards low levels of ADH.

iii. The ability of the hormone to concentrate urine decreases slowly.

Q5. Identify ‘a’, ‘b’, ‘c’ and ‘d’ in the given table.

Animals Mode of Excretion Excretory Product
Lizard Uricotelism ‘b’
Elephant ‘a’ Urea
‘c’ Ammonotelism Ammonia
Cockroach ‘d’ Uric acid

Answer:

Animals Mode of Excretion Excretory Product
Lizard Uricotelism Uric acid
Elephant Ureotelism Urea
Fish Ammonotelism Ammonia
Cockroach Uricotelism Uric acid

Q6. Fill in the gaps:
(a) Ascending limb of Henle’s loop is _______ to water whereas the descending limb is _______ to it.
(b) Reabsorption of water from distal parts of the tubules is facilitated by hormone _______.
(c) Dialysis fluid contains all the constituents as in plasma except _______.
(d) A healthy adult human excretes (on an average) _______ gm of urea/day.

Answer: (a) Ascending limb of Henle’s loop is impermeable to water whereas the descending limb is permeable to it.

(b) Reabsorption of water from distal parts of the tubules is facilitated by hormone antidiuretic hormone or vasopressin.

(c) Dialysis fluid contains all the constituents as in plasma except the nitrogenous waste.

(d) A healthy adult human excretes (on an average) 25-30 gm of urea/day.

Q7. Name the following:
(a) A chordate animal having flame cells as excretory structures
(b) Cortical portions projecting between the medullary pyramids in the human kidney
(c) A loop of capillary running parallel to Henle’s loop

Answer: (a) Amphioxus

(b) Columns of Bertini

(c) Vasa recta

Q8. What is the significance of juxta glomerular apparatus (JGA) in kidney function?

Answer: Kidneys have a microscopic structure called juxta glomerular apparatus (JGA) between an afferent arteriole and distal convoluted tubule of the same nephron that is required for the maintenance of uniform Glomerular Filtration Rate (GFR). Whenever there is a fall in GFR, cells of juxta glomerular apparatus release a hormone called renin which travels into the bloodstream of glomerulus where it converts angiotensinogen into angiotensin I. Angiotensin I further gets converted to angiotensin II. Angiotensin helps in constriction of smooth muscle cells of the blood vessel that increases the blood pressure. Increased blood pressure results in an increase in glomerular filtration rate. Angiotensin also stimulates the secretion of aldosterone from adrenal glands. Aldosterone increases the absorption of sodium ions and water which increases blood pressure and brings the GFR back to normal. Thus, juxta glomerular apparatus plays a complex regulatory role in the functioning of the kidney.

Flow chart showing the role of juxta glomerular apparatus (JGA) in kidney function

Q9. Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic. Why?

Answer: Terrestrial animals are generally either ureotelic or uricotelic because it is an adaptation to conserve water. In these animals, water soluble ammonia is converted into less soluble urea and uric acid. These are then filtered by the kidney and excreted out with urine. This requires minimum water; thus the animal conserves water.

Q10. What is meant by the term osmoregulation?

Answer: Osmoregulation is a process by which organisms maintain homeostasis of water content in their body. It protects body fluids from becoming too dilute or too concentrated. For example, large amount of water goes into the nephrons from blood during the process of glomerular filtration. This water is reabsorbed by medullary interstitium and transferred again to blood in vasa recta thus, maintaining water homeostasis in blood.

Q11. Match the items of column I with those of column II:

Column I Column II
(a) Ammonotelism (i) Birds
(b) Bowman’s capsule (ii) Water reabsorption
(c) Micturition (iii) Bony fish
(d) Uricotelism (iv) Urinary bladder
(e) ADH (v) Renal tubule

Answer:

Column I Column II
(a) Ammonotelism (iii) Bony fish
(b) Bowman’s capsule (v) Renal tubule
(c) Micturition (iv) Urinary bladder
(d) Uricotelism (i) Birds
(e) ADH (ii) Water reabsorption

Q12. Explain micturition.

Answer: Micturition is the process of releasing of urine from urinary bladder. Urine formed by kidney is carried to urinary bladder where it is stored. When urinary bladder is filled with urine, it exerts the pressure on bladder wall. Pressure activates receptors present in bladder wall that send signals to central nervous system (CNS). The CNS sends the signal for the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincter causing the release of urine.

An adult human excretes about 1 to 1.5 litres of urine per day. The urine is light yellow coloured watery fluid which is slightly acidic with a characteristic odour.

Related Study Material on Extramarks

Q.1 Any damage caused to villi and microvilli may lead to
1. the decrease in surface area for absorption
2. the decrease in solute concentration in the alimentary canal
3. the increase in water absorption
4. the increase in solute concentration in the alimentary canal

Marks:1

Ans

Any damage caused to villi and microvilli may lead to a decrease in the surface area for the absorption and solute concentration in the alimentary canal because they increase the surface area for the absorption of the food nutrients in the small intestine.

Q.2 In the process of excretion, the waste products from body are passed into the ______, from where it is egested through the_____.

Marks:1

Ans

Excretion is a process by which metabolic waste is eliminated from an organism. During the process of excretion in human, from the colon of large intestine, the waste is passed into the rectum, from where it is egested through the anus by the process of defecation.

Q.3 Match the organs given in the column I with the features given in column II and select the correct options.

Column I Column II
(A) Duodenum (i) A cartilaginous flap
(B) Epiglottis (ii) ?U? shaped structure emerging from the stomach
(C) Glottis (iii) Opening of wind pipe

Marks:1

Ans

The duodenum is the first part of the small intestine, which is a ?U? shaped structure. The epiglottis is a cartilaginous flap in the throat that prevents food from entering into the windpipe and the lungs. The larynx, commonly called the voice box or glottis, leads to the trachea of wind pipe.

Q.4 Diarrhoea occurs in cholera patients due to the loss of chloride ions and dehydration. Identify the organ in the human alimentary canal that is affected by the cholera toxin.

Marks:1

Ans

Small intestine

The cholera toxin released by the Vibrio cholerae bacterium causes an increased amount of water to be released from the cells that line the intestines. Due to this, the water potential inside the small intestine is reduced and as a result, water moves into the small intestine from the surrounding cells by the process of osmosis down the water potential gradient.

Q.5 When we eat cooked rice it tastes sweet and good. This is due to the

Marks:1

Ans

Action of saliva.

Rice contains starch which is tasteless. The saliva in our mouth contains an enzyme called salivary amylase. When we chew rice, salivary amylase converts the starch into sugar, which is sweet to taste.

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