Excretory Products and Their Elimination — Class 11 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 11 Biology chapter "Excretory Products and Their Elimination" — 8 important questions with detailed answers for CBSE board exam preparation.

TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Excretory Products and Their Elimination" — 8 important questions with detailed answer…

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Key Questions Covered:

  1. Define excretion. Why is it necessary for living organisms?
  2. Name the main nitrogenous wastes in humans and their sources.
  3. Draw and label a nephron. What are its main parts?
  4. Explain the three processes involved in urine formation.
  5. What is the role of ADH and aldosterone in osmoregulation?
  6. What is the difference between a pyramid of energy and a pyramid of biomass?
  7. + 2 more questions in the full chapter

Solutions Summary:

Question Status
Define excretion. Why is it necessary for living organisms? ✓ Solved
Name the main nitrogenous wastes in humans and their sour… ✓ Solved
Draw and label a nephron. What are its main parts? ✓ Solved
Explain the three processes involved in urine formation. ✓ Solved
What is the role of ADH and aldosterone in osmoregulation? ✓ Solved
What is the difference between a pyramid of energy and a … ✓ Solved

Showing 6 of 8 questions

Q1: Define excretion. Why is it necessary for living organisms?

Excretion is the process of removing metabolic waste products from the body. It is necessary because: - Prevents accumulation of toxic waste like urea, uric acid, and CO2 - Maintains internal osmotic balance and pH - Prevents damage to cells and tissues - Helps maintain homeostasis

Q2: Name the main nitrogenous wastes in humans and their sources.

Main nitrogenous wastes: - Urea: formed from breakdown of amino acids and proteins in liver; most common in humans - Uric acid: end product of nucleic acid metabolism; requires water for excretion - Ammonia: toxic, produced during amino acid catabolism; converted to urea in liver

Q3: Draw and label a nephron. What are its main parts?

Main parts of nephron: - Renal corpuscle: Bowman's capsule + glomerulus (filtration) - Proximal convoluted tubule: selective reabsorption of glucose, amino acids, ions - Loop of Henle: creates concentration gradient for water reabsorption - Distal convoluted tubule: fine-tuning of reabsorption - Collecting duct: final concentration of urine, water reabsorption via ADH

Q4: Explain the three processes involved in urine formation.

Three-stage process: - Ultrafiltration: in Bowman's capsule; high blood pressure forces small molecules (glucose, urea, ions, water) through glomerular filtration barrier; large proteins and RBCs remain in blood - Selective reabsorption: useful substances reabsorbed in PCT (glucose, amino acids, 80% ions, 85% water) - Tubular secretion: additional wastes secreted from blood into tubule lumen for concentration; occurs in DCT and collecting duct

Q5: What is the role of ADH and aldosterone in osmoregulation?

ADH (antidiuretic hormone): - Released by pituitary when blood osmotic pressure increases - Increases permeability of collecting duct to water - More water reabsorbed, concentrated urine formed Aldosterone: - Secreted by adrenal cortex - Increases reabsorption of Na+ and water - Maintains blood pressure and Na+ balance

Q6: What is the difference between a pyramid of energy and a pyramid of biomass?

Energy pyramid: - Always upright; each trophic level has less energy than the one below - Energy loss at each transfer (~10% rule) - Cannot be inverted Biomass pyramid: - Usually upright but can be inverted - In aquatic ecosystems, small algae support large zooplankton - Biomass does not directly relate to energy content

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