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NCERT Solutions for Class 11 Biology Chapter 16 Excretory Products and Their Elimination
Edited By Irshad Anwar | Updated on Jun 19, 2025 12:00 PM IST
The NCERT Solutions for Class 11 Biology Chapter 16 Excretory Products and Their Elimination chapter explains how the human body eliminates waste products. The chapter deals with important concepts like excretion in humans, formation of urine, structure and function of renal tubules, micturition, and disorders of the excretory system. It is an important chapter for CBSE exams and competitive entrance exams, and these NCERT Solutions provide detailed answers to help students learn and excel at the concepts.
This Story also Contains
- NCERT Solutions For Class 11 Biology Chapter 16 - PDF Download
- Access to NCERT Solutions for Class 11 Biology Chapter 16 - (Exercise Questions)
- Approach to Solve Questions of Class 11 Chapter 16 Biology
- Important Question from Chapter 16 Excretory Products and Their Elimination
- What Extra Should Students Study Beyond the NCERT for NEET?
- NCERT Solutions for Class 11 Biology - Chapter Wise
These NCERT Solutions for Class 11 of the Excretory Products and Their Elimination chapter explain how our body eliminates waste using organs such as the kidneys, liver, and skin. It discusses how urine is produced and how toxic substances are eliminated to maintain the body in a healthy state. The NCERT Solutions for Class 11 Biology are easy to understand and include practice questions to help students prepare well for exams, highlighting the importance of the excretory system.
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NCERT Solutions For Class 11 Biology Chapter 16 - PDF Download
The solutions in PDF can be downloaded hereDownload PDF
Access to NCERT Solutions for Class 11 Biology Chapter 16 - (Exercise Questions)
The complete exercise and in-text answers are given below:
Q1. Define Glomerular Filtration Rate (GFR)
Answer: The Glomerular Filtration Rate (GFR) is a measure of how well the kidneys filter the blood.
- GFR is the rate of fluid filtered by all of the nephrons in both kidneys per minute.
- Normal GFR in healthy adults is roughly 125 mL/min (180 litres per day).
Q2. Explain the autoregulatory mechanism of GFR.
Answer: The kidneys contain a systematic mechanism to control GFR through the Juxtaglomerular apparatus (JGA).
- The JGA senses reduced GFR and releases renin, activating the renin-angiotensin system to cause vasoconstriction and increase blood pressure.
- This action restores glomerular filtration pressure, bringing GFR back to normal.
Q3. 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.
Answer: The true and false statements are mentioned below:
Statement | True/False |
(a) Micturition is carried out by a reflex. | True |
(b) ADH helps in water elimination, making the urine hypotonic. | False |
(c) Protein-free fluid is filtered from blood plasma into the Bowman’s capsule. | True |
(d) Henle’s loop plays an important role in concentrating the urine. | True |
(e) Glucose is actively reabsorbed in the proximal convoluted tubule. | True |
Q4. Give a brief account of the counter-current mechanism.
Answer: The countercurrent mechanism plays a crucial role in the concentration of urine and water conservation.
- It supports a medullary osmotic gradient (300 → 1200 mOsm/L).
- The Loop of Henle removes NaCl (ascending limb) and urea (collecting duct), while the vasa recta keep this gradient maintained by the countercurrent exchange.
Q5. Describe the role of the liver, lungs and skin in excretion
Answer: Various organs contribute to the excretion processes of the body, each with distinct functions.
| Organ | Role |
|---|---|
| Liver | Converts ammonia to urea and excretes bile pigments/drugs. |
| Lungs | Remove carbon dioxide through exhalation. |
| Skin | Sweat glands excrete water and salts; sebaceous glands secrete oils. |
Answer: Passing urine out of the bladder is called Micturition
- As the urine builds up, bladder stretch initiates a spinal reflex; urethral sphincters relax, and muscles of the bladder contract.
- Adults typically urinate approximately 1–1.5 litres per day.
Q7. 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: The correct matching is a-iii, b-v, c-iv, d-i, e-ii
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 |
Q8. What is meant by the term osmoregulation?
Answer: Osmoregulation is important for the balance of water and salts in body fluids.
- It controls water and ionic content to maintain the internal environment constant.
Q9. Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic. Why?
Answer: Terrestrial animals primarily excrete urea or uric acid due to ammonia's toxicity and water requirements.
| Excretion Type | Toxicity Level | Water Needed | Example |
|---|---|---|---|
| Ammonotelism | High | High | Fish |
| Ureotelism | Low | Moderate | Mammals |
| Uricotelism | Very low | Minimal | Birds/Reptiles |
Q10. What is the significance of the juxta-glomerular apparatus (JGA) in kidney function?
Answer: The JGA has an important function in the control of kidney function through the monitoring of blood pressure.
- It secretes renin when GFR is low, which stimulates angiotensin II to constrict blood vessels and stimulate the secretion of aldosterone.
- This increases blood pressure and glomerular filtration rate.
Q11. Name the following:
(a) A chordate animal having flame cells as excretory structures
Answer: A chordate animal having flame cells as excretory structures is an Amphioxus.
Q11. Name the following:
(b) Cortical portions projecting between the medullary pyramids in the human kidney
Answer: Cortical portions projecting between the medullary pyramids in the human kidney are called columns of Bertini.
Q11. Name the following:
(c) A loop of capillary running parallel to Henle's loop.
Answer: A loop of capillary running parallel to Henle’s loop is the vasa recta.
Q12. Fill in the gaps :
(a) The ascending limb of Henle’s loop is _______ to water, whereas the descending limb is _______ to it.
(b) Reabsorption of water from the 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 average) _______ gm of urea/day.
Answer:
(a) The ascending limb of Henle’s loop is impermeable to water, whereas the descending limb is permeable to it.
(b) Reabsorption of water from the distal parts of the tubules is facilitated by the hormone ADH.
(c) Dialysis fluid contains all the constituents as in plasma except nitrogenous wastes.
(d) A healthy adult human excretes (on average) 20-30 gm of urea/day.
Approach to Solve Questions of Class 11 Chapter 16 Biology
To answer questions from this chapter correctly and confidently, follow these simple steps:
Start by understanding the types of nitrogenous wastes like ammonia, urea, and uric acid, and know which organisms excrete which type.
Learn the structure and function of the human excretory system, especially the kidneys and nephrons.
Understand the process of urine formation – filtration, reabsorption, and tubular secretion.
Focus on how kidneys regulate water and salts in the body (osmoregulation).
Revise disorders related to the excretory system, such as kidney stones, uremia, dialysis, and kidney transplantation.
Practice diagram-based questions, especially of the nephron and excretory system.
Important Question from Chapter 16 Excretory Products and Their Elimination
Take a look at this important question that can help in increasing the understanding of the concept.
Question: Which of the following is not a component of the human excretory system?
i. Kidneys
ii. Ureters
iii. Lungs
iv. Urethra
Options:
i and ii
ii and iii
i and iii
iii and iv
Answer: Option 4
Solution: Lungs are not included in the excretory system and are responsible for expelling nitrogenous wastes such as urea. The urinary system includes the kidneys, ureters, urinary bladder, and urethra responsible for excretion. Lungs are respiratory organs that eliminate carbon dioxide but not nitrogenous wastes.
Also, check the NCERT Books and NCERT Syllabus here :
What Extra Should Students Study Beyond the NCERT for NEET?
Here is a table for all the important topics from the chapter:
NCERT Solutions for Class 11 Biology - Chapter Wise
Below are the Chapterwise answers:
Frequently Asked Questions (FAQs)
1. What are the important topics covered in NCERT Solutions for Class 11 Biology Chapter 16?
The NCERT Solutions for Class 11 Biology Chapter 16 covers the excretory system, kidney structure, nephron function, urine formation, micturition, and disorders like kidney stones and UTIs. It explains processes like ultrafiltration, counter-current mechanisms, and the role of hormones like ADH in regulating water balance.
2. Name the loop of capillary running parallel to the Henle's loop given in the excretion class 11.
A loop of capillary running parallel to the Henle’s loop is vasa rectum.
3. What are the benefits of the solutions for NCERT class 11 biology chapter 16 excretory products and their elimination?
The benefits of the solutions for NCERT class 11 biology chapter 16 excretory products and their elimination are listed below:
- NCERT is the base of your learning.
- These solutions will also help you with competitive exams like NEET.
- You will get all the answers that will help you to score good marks in the exam.
- This will also help you in your 12th board exam.
- This chapter will also boost your knowledge
To score well in the examination, follow the NCERT syllabus and solve the exercises given in the NCERT Book. To practice more problems, students must refer to NCERT Exemplar.
4. What are the common disorders of the excretory system?
Common disorders include kidney stones, renal failure, gout, and urinary tract infections (UTIs).
5. How do kidneys help in the process of excretion in humans?
Kidneys filter blood to remove waste products like urea and excess water. They also regulate electrolyte and water balance through processes of filtration, reabsorption, and secretion.
6. What is the role of nephrons in urine formation?
Nephrons are the functional units of kidneys. They filter blood in the glomerulus, reabsorb essential substances in the tubules, and secrete additional waste products into the urine.
7. How do different organisms excrete nitrogenous waste?
Different organisms excrete nitrogenous waste in different forms: ammonotelic organisms (like fish) excrete ammonia, ureotelic organisms (like humans) excrete urea, and uricotelic organisms (like birds) excrete uric acid.
8. What are the differences between ammonotelic, ureotelic, and uricotelic organisms?
Ammonotelic organisms excrete ammonia, which is highly toxic and requires a lot of water. Ureotelic organisms excrete urea, which is less toxic and requires moderate water. Uricotelic organisms excrete uric acid, which is least toxic and requires minimal water.
9. What is the significance of ultrafiltration in urine formation?
Ultrafiltration is the process by which blood is filtered in the glomerulus to form a filtrate that will eventually become urine. It removes waste and excess fluids from the blood.
10. How does the counter-current mechanism help in urine concentration?
The counter-current mechanism in the Loop of Henle creates a concentration gradient in the kidney medulla. This allows water to be reabsorbed in the collecting ducts, concentrating the urine.
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