NCERT Solutions for Class 11 Biology Chapter 16 Question Answer

NCERT Solutions for Class 11 Biology Chapter 16: Chapter 16 of Class 11 Biology, Excretory Products and Their Elimination, explores the vital process of waste removal in organisms to maintain homeostasis. It explains the formation and excretion of nitrogenous wastes like ammonia, urea, and uric acid in different animals.

NCERT Solutions for Class 11 Biology Chapter 16 Overview

NCERT Solutions for Class 11 Biology Chapter 16 PDF

NCERT Solutions for Class 11 Biology Chapter 16 PDF

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

1. Define Glomerular Filtration Rate (GFR).

Solution:

2. Explain the autoregulatory mechanism of GFR.

Solution:

3. 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 urine.

(e) Glucose is actively reabsorbed in the proximal convoluted tubule.

Solution:

4. Give a brief account of the counter-current mechanism.

Solution:

1. Henle’s loop
2. Vasa recta

• Henle’s loop is a U-shaped part of the nephron. The flow of blood in the two branches of the tube is in the opposite direction, which gives rise to the counter currents.
• Vasa recta, on the other hand, is an efferent arteriole that forms a capillary network around the tubules in the renal medulla, which tracks parallel to the Henle’s loop. Vasa recta are also U-shaped. The flow of blood is in opposite directions in the two limbs of the vasa recta. Hence, the blood that enters the renal medulla in the descending limb comes in close proximity with the outgoing blood in the ascending limb

• The concentration gradient is maintained by the countercurrent process, which raises the osmolarity in the cortex from 300 mOsmolL-1 to roughly 1200 mOsmolL-1 in the inner medulla. Water can therefore flow more easily from the collecting tubules as a result. The flow of urea and NaCl is what causes the concentration gradient.

5. Describe the role of the liver, lungs and skin in excretion.

Solution:

• It is the chief site for the removal of inactivated products of steroid hormones, cholesterol, drugs and vitamins.
• Dead erythrocytes possess haemoglobin. This haemoglobin is also disintegrated into bile pigments – biliverdin and bilirubin, which are treated wastes.
• Bile carries substances to the intestine, which along with the wastes, are eliminated.

• Carbon dioxide is expelled from the body by the lungs.
• Approximately it eliminates 200ml of carbon dioxide every minute.
• Water in the form of water vapour is also eliminated.
• Loss of water increases in colder conditions and declines in humid, hot conditions.
• During the process of expiration, several volatile materials are also ejected.

• It is primarily in charge of the body's thermoregulation, or cooling.
• The skin eliminates perspiration. There are nitrogenous wastes in it. Sweat is only expelled when it's required, as when the body needs to chill down.
• The sweat glands emit perspiration, which contains lactic acid, urea, and sodium chloride.
• The sebaceous glands extract waxes, sterols, and hydrocarbons from the sebum.
• Sebum provides the skin with an oily, protective layer.

6. Explain micturition.

Solution:

7. Match the items of column I with those of column II.

Solution:

8. What is meant by the term osmoregulation?

Solution:

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

Solution:

10. What is the significance of the juxtaglomerular apparatus (JGA) in kidney function?

Solution:

• Its mechanism is via the renin-angiotensin-aldosterone system (RAAS).
• When the glomerular filtration rate dips, the juxtaglomerular apparatus stimulates, causing the secretion of renin.
• This renin converts a protein into a peptide, i.e., angiotensinogen, to angiotensin.
• Angiotensin is a hormone that elevates the GFR and the flow of blood in these three ways:
  1. Narrowing the efferent arterioles causes an increase in glomerular pressure.
  2. Triggering the walls of the PCT in order to reabsorb more water and NaCl.
  3. Triggers the adrenal gland to secrete aldosterone that facilitates reabsorption of water and NaCl in the DCT.
• The volume of blood and blood pressure thereby increases. The hypertonic urine and urine volume decreases.

11. 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.

Solution:

12. 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 contain all the constituents as in plasma except _______.

(d) A healthy adult human excretes (on an average) _______ gm of urea/day

Solution:

1. Impermeable, permeable
2. Vasopressin (anti-diuretic hormone)
3. Nitrogenous waste
4. 25-30

Benefits of Using NCERT Solutions for Class 11 Biology Chapter 16

Concept Clarity : Simplifies complex topics like urine formation, osmoregulation, and hormonal regulation.

Exam Focus : Provides accurate answers aligned with NCERT, helping students score better in exams.

Efficient Revision : Serves as a quick reference for revising key concepts and processes.

Improved Understanding : Enhances comprehension of disorders like uremia and the role of dialysis.

Practice Support : Offers well-structured answers to strengthen problem-solving skills.

Easy Access : Available in PDF format, ensuring convenience for students to study anytime.

Curriculum-Based : Fully adheres to NCERT guidelines, ensuring relevancy for exams.