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Chapter Analysis
Intermediate12 pages • EnglishQuick Summary
The chapter 'Excretory Products and their Elimination' in Class 11 Biology discusses the mechanisms and importance of excreting metabolic wastes such as ammonia, urea, and uric acid. It explains the human excretory system, focusing on the structure and function of kidneys and the process of urine formation. It also covers the role of other organs like the liver, lungs, and skin in excretion and the disorders related to the excretory system, along with the mechanisms involved in kidney function and urine concentration.
Key Topics
- •Human excretory system
- •Urine formation and its stages
- •Function of renal tubules
- •Mechanism of concentration of the filtrate
- •Regulation of kidney function
- •Micturition process
- •Role of other organs in excretion
- •Disorders of the excretory system
Learning Objectives
- ✓Understand the structure and function of human excretory system
- ✓Learn the processes involved in urine formation
- ✓Identify the role of the renal tubule and its components
- ✓Explain the counter-current mechanism in nephrons
- ✓Understand how kidneys regulate body fluids and electrolytes
- ✓Recognize the significance of other organs in the excretory process
Questions in Chapter
Define Glomerular Filtration Rate (GFR)
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Explain the autoregulatory mechanism of GFR.
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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.
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Give a brief account of the counter current mechanism.
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Describe the role of liver, lungs and skin in excretion.
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Explain micturition.
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Match the items of column I with those of column II: Column I (a) Ammonotelism, (b) Bowman's capsule, (c) Micturition, (d) Uricotelism, (e) ADH with Column II (i) Birds, (ii) Water reabsorption, (iii) Bony fish, (iv) Urinary bladder, (v) Renal tubule.
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What is meant by the term osmoregulation?
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Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?
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What is the significance of juxta glomerular apparatus (JGA) in kidney function?
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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.
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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.
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Additional Practice Questions
What are the main nitrogenous wastes excreted by different animals, and how does habitat influence this process?
mediumAnswer: Ammonia, urea, and uric acid are the main nitrogenous wastes. The nature of nitrogenous waste depends on the habitat of the animal due to water availability. Ammonotelic animals in aquatic environments excrete ammonia, ureotelic animals like mammals excrete urea, and uricotelic animals like birds excrete uric acid.
Explain the role of the kidneys in maintaining the body’s acid-base and ionic balance.
hardAnswer: Kidneys help maintain acid-base balance through selective reabsorption and secretion of ions like hydrogen, potassium, and bicarbonate. They adjust ion reabsorption to regulate blood chemistry, thereby controlling the body’s osmolarity and pH balance.
Discuss how the counter-current mechanism in the nephron aids in urine concentration.
hardAnswer: The counter-current mechanism involves the loop of Henle, where the descending limb allows water reabsorption and the ascending limb allows solute reabsorption. The vasa recta maintain a concentration gradient in the medullary interstitium, facilitating water reabsorption from the collecting duct and concentrating the urine.
How do the kidneys respond to changes in blood pressure and body fluid levels to maintain homeostasis?
hardAnswer: Kidneys regulate fluid balance through the renin-angiotensin-aldosterone system. Low blood pressure triggers renin release, converting angiotensinogen to angiotensin, raising blood pressure and prompting aldosterone release for sodium and water reabsorption. ADH from the hypothalamus increases water reabsorption in kidney tubules, adjusting blood pressure and osmolarity.
What excretory adaptations are seen in terrestrial vs. aquatic animals?
mediumAnswer: Aquatic animals often excrete ammonia directly due to abundant water, while terrestrial animals convert ammonia to less toxic urea or uric acid to conserve water. Ureotelic adaptations are common in mammals and ureotelic adaptations in birds and reptiles.