NCERT Solutions for Class 11 Biology Chapter 16 Excretory Products and Their Elimination

NCERT Solutions for Class 11 Biology Chapter 16 discusses how your body eliminates waste. It has topics like excretion in humans, the formation of urine, renal tubules, the process of micturition, and disorders of the excretory system. This chapter is very important for CBSE Exams and also various entrance exams which are to come your way, and these NCERT Solutions will guide you through it step by step.

New: Get up to 90% Scholarship on NEET/JEE Coaching from top Coaching Institutes

NEET Scholarship Test Kit (Class 11): Narayana | Physics Wallah | Aakash | ALLEN

Browse: NEET papers with solutions | Most scoring concepts for NEET

This Story also Contains

1. NCERT Solutions For Class 11 Biology Excretory Products and their Elimination - PDF Download
2. Access to NCERT Solutions for Class 11 Biology Chapter 16 - (Solved Exercise)
3. Overview of NCERT Class 11 Biology Chapter 16 – Excretory Products and Their Elimination
4. Important Topics of Solutions for NCERT Class 11 Biology Chapter 16 - Excretory Products and Their Elimination
5. Key Concepts of This Chapter
6. Important diagrams in Class 11 Biology Chapter 16 - Excretory Products and Their Elimination
7. NCERT Solutions for Class 11 Biology - Chapter Wise
8. Practice Questions On Excretory Products and Their Elimination

This chapter explains 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 excretion.

NCERT Solutions For Class 11 Biology Excretory Products and their Elimination - PDF Download

The solutions in PDF can be downloaded hereDownload PDF

• NCERT Notes for Class 11 Biology Chapter 16 Excretory Products and Their Elimination
• NCERT Exemplar for Class 11 Biology Chapter 16 Excretory Products and Their Elimination

Access to NCERT Solutions for Class 11 Biology Chapter 16 - (Solved Exercise)

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 an intrinsic 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:

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 sustains 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.

Q6. Explain micturition

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

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.

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 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 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.

Overview of NCERT Class 11 Biology Chapter 16 – Excretory Products and Their Elimination

This chapter is a part of Unit 5, Human Physiology, of the CBSE syllabus for the 2025-26 session. This unit holds significant weightage as it accounts for nearly 25% of the overall marks.These answers provide solutions to all the exercise questions from the chapter. Students must give special regard to this chapter as it explains the human excretory system and its functioning.

This chapter discusses how your body eliminates waste. It discusses:

• The Human Excretory System: What body parts are involved (like kidneys, ureters, bladder, and urethra) and how do they work together?

• Urine Formation: The three important steps - filtration, reabsorption, and secretion - that occur in your kidneys to form urine.

NCERT Solutions for Class 11 - Subject-wise

Key Parts of the Excretory System

Here's a simple table to understand the main parts:

Important Topics of Solutions for NCERT Class 11 Biology Chapter 16 - Excretory Products and Their Elimination

The important topics of the chapter are given below:

If you cannot read or answer questions in this chapter, then study the chapter thoroughly and then try to answer the questions yourself and match your answers accordingly. It will not only make you prepared for school exams but also for competitive exams like NEET, in which questions related to these chapters have been added.

Key Concepts of This Chapter

• Glomerular Filtration Rate (GFR): This is an indication of how effectively your kidneys filter your blood. If your Glomerular Filtration Rate (GFR) is normal, then your kidneys are working correctly.

• Countercurrent Mechanism: The countercurrent mechanism unique process of the kidneys that is responsible for making your urine more concentrated so that you don't lose excess water.

• Micturition: It's the act of expelling urine.It has the bladder muscles contracting and relaxing the urethral sphincter.

How Other Organs Help

It's not only the kidneys! The liver, lungs, and skin also contribute to waste removal:

• The liver breaks down harmful substances and produces urea.

• The lungs get rid of carbon dioxide when you breathe out.

• The skin releases sweat, which contains salts and water.
  

Important diagrams in Class 11 Biology Chapter 16 - Excretory Products and Their Elimination

Here are some important diagrams from Excretory Products and Their Elimination:

• Human Excretory System
  This diagram shows the complete human excretory system, including the kidneys, ureters, bladder, and urethra.

• Kidneys

This diagram shows the internal structure of the kidneys.

• Nephron Structure
  The nephron is the functional unit of the kidney, and this diagram shows its detailed structure, including the glomerulus and renal tubule.

• Ultrafiltration
  This diagram Illustrates The Process Of Ultrafiltration In The Glomerulus

• Hemodialysis

  A hemodialysis machine functions as an artificial kidney, filtering waste and excess fluids from the blood of patients with kidney failure.

  

  
  

NCERT Solutions for Class 11 Biology - Chapter Wise

Below mentioned are the Chapterwise answers:

Practice Questions On Excretory Products and Their Elimination

Question: Which of the following is not a component of the human excretory system?

i. Kidneys

ii. Ureters

iii. Lungs

iv. Urethra

Options:

1. i and ii

2. ii and iii

3. i and iii

4. iii and iv

Answer: Option 4

Solution: Lungs are not included in the excretory system responsible for expelling nitrogenous wastes such as urea. The urinary system includes kidneys, ureters, urinary bladder, and urethra responsible for excretion. Lungs are respiratory organs that eliminate carbon dioxide but not nitrogenous wastes.

Question: What is the functional and structural unit of the kidney?

Answer: Nephron

Question: Give the two primary nitrogenous waste products excreted by human beings.

Answer: Urea and creatinine

Question: Why is urea less harmful than ammonia?

Answer: Urea is less harmful since it is a more stable molecule and is transported in blood safely without causing damage, whereas ammonia is very toxic and needs to be diluted and expelled rapidly.

Question: Which component of the nephron is involved in ultrafiltration?

Answer: Bowman's capsule (in association with the glomerulus)

Question: Describe the function of antidiuretic hormone (ADH) in osmoregulation.

Answer: ADH increases water reabsorption in the kidney tubules, particularly the collecting ducts, decreasing urine volume and assisting in the maintenance of water balance within the body.

Question: What is dialysis and when is it required?

Answer: Dialysis is a medical treatment employed to eliminate waste products and excess fluid from the blood when kidneys cannot do so, usually in renal failure.

Question: Match the following:

A. Ammonotelic organisms – i. Birds and reptiles

B. Ureotelic organisms – ii. Amphibians and mammals

C. Uricotelic organisms – iii. Aquatic invertebrates and bony fishes

Options:

1. A-i, B-ii, C-iii

2. A-iii, B-ii, C-i

3. A-ii, B-i, C-iii

4. A-iii, B-i, C-ii

Answer: Option 2

Solution:

• Ammonotelic animals excrete ammonia – present in aquatic invertebrates and bony fishes.

• Ureotelic animals excrete urea – comprises amphibians and mammals.

• Uricotelic animals excrete uric acid – including birds and reptiles.

Question: Explain the process of urine formation.

Answer: Urine formation is a three-step process:

• Glomerular filtration – Blood is pressure-filtered in the glomerulus the filtrate is received in Bowman's capsule.
• Tubular reabsorption – Helpful substances such as glucose, amino acids, and water are absorbed into the bloodstream.
• Tubular secretion – Waste products such as potassium ions and hydrogen ions are secreted into the tubule to create ionic balance and pH.

The final urine is then concentrated and stored in the renal pelvis before passing into the ureter.

Also, check the NCERT Books and NCERT Syllabus here :

• NCERT Books Class 11 Biology

• NCERT Syllabus Class 11 Biology

• NCERT Books Class 11

• NCERT Syllabus Class 11

Knowing how our body removes waste, as discussed in NCERT Solutions for Class 11 Biology Chapter 16 on "Excretory Products and Their Elimination," is important to learn. These solutions tell us how our kidneys, liver, and skin contribute to cleansing our blood. Learning these solutions will make you familiar with urine formation, kidney function, and filtration of waste to perform better in both the board and entrance examinations.