Class 11 Biology

Chapter 16 Solutions — Excretory Products and Their Elimination

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Solutions

Overview

Step-by-step NCERT solutions for Excretory Products and Their Elimination (Chapter 16, NCERT Class 11 Biology) — every question and answer worked out in full, not just the final result. You can also read the Excretory Products and Their Elimination textbook chapter.

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All 12 questions in Excretory Products and Their Elimination are solved in the PDF. Here's what's inside, exercise by exercise:

Exercises

Define Glomerular Filtration Rate (GFR)
Explain the autoregulatory mechanism of GFR.
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 the urine.
- (e) Glucose is actively reabsorbed in the proximal convoluted tubule.
Give a brief account of the counter current mechanism.
Describe the role of liver, lungs and skin in excretion.
Explain micturition.
7.
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
- (d) ADH
- (v) Renal tubule
What is meant by the term osmoregulation?
Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why ?
What is the significance of juxta glomerular apparatus (JGA) in kidney function?
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 the Henle's loop.
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.

Sample

Worked examples

2 questions from Excretory Products and Their Elimination, solved step by step.

Exercises

Define Glomerular Filtration Rate (GFR)

Glomerular Filtration Rate (GFR) is the amount of glomerular filtrate formed in both kidneys per minute.

In a healthy adult, GFR is approximately 125 mL/minute, which amounts to about 180 litres of filtrate per day.

GFR is determined by the glomerular capillary blood pressure, which drives ultrafiltration of blood through the three-layered filtration barrier: the glomerular endothelium, the basement membrane, and the podocyte epithelium of Bowman's capsule.

Answer: GFR is the volume of glomerular filtrate formed per minute — approximately 125 mL/min (180 L/day) in a healthy adult.

Exercises

What is meant by the term osmoregulation?

Osmoregulation is the process by which an organism actively regulates and maintains the osmotic concentration (water and ion balance) of its body fluids within a narrow, physiologically acceptable range, despite fluctuations in the external environment or intake.

In animals, osmoregulation involves controlling the concentration of water, salts (Na+, K+, Cl-, etc.) and other solutes in blood and body fluids.

In humans, the kidneys are the primary organs of osmoregulation. They adjust the volume and concentration of urine to maintain blood osmolarity at ~300 mOsmol L-1. Hormones such as ADH (which promotes water retention) and aldosterone (which promotes Na+ reabsorption) are key regulators.

Osmoregulation is essential for proper cell function — cells swell or shrink if surrounding fluid osmolarity changes significantly, disrupting normal metabolism.

Answer: Osmoregulation is the active regulation of water and ionic (osmotic) balance of body fluids. Kidneys are the primary osmoregulatory organs in humans; ADH and aldosterone are key hormones maintaining blood osmolarity at ~300 mOsmol/L.

All 12 questions in Excretory Products and Their Elimination are solved step by step in the Solutions PDF above.

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Chapter 16 Solutions — Excretory Products and Their Elimination

Overview

What these solutions cover

Exercises

Worked examples

Define Glomerular Filtration Rate (GFR)

What is meant by the term osmoregulation?

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