Excretion — Telangana (SSC) Class 10 Science Solutions (Free)
Free step-by-step Telangana (SSC) Class 10 Science solutions for "Excretion" — important questions with detailed answers, download PDF for board exam preparation.
TL;DR: Free step-by-step Telangana (SSC) Class 10 Science solutions for "Excretion" — important questions with detailed answers, download PDF for board exam…
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Q1: Define excretion and distinguish it from egestion. Name the main excretory products in humans.
Excretion: Removal of metabolic waste products from body (produced during cellular metabolism).
Egestion: Removal of undigested food (from digestive tract); not metabolic waste; not excretion.
Key difference:
• Excretion: Metabolic waste (urea, CO₂); removed from cells/blood; requires energy
• Egestion: Undigested food residue; removed from digestive tract; passive elimination
Main excretory products in humans:
1. Carbon dioxide (CO₂):
• From cellular respiration
• Excretion site: Lungs…
Q2: Describe the structure of human kidney with diagram description. What is the functional unit of kidney?
Human kidney structure:
• Bean-shaped organ (~10 cm long)
• Outer layer: Renal cortex (contains filtering units)
• Middle layer: Renal medulla (contains loops and collecting ducts)
• Inner region: Renal pelvis (collects urine; leads to ureter)
• One ureter per kidney → transports urine to bladder
Microscopic structure:
Renal capsule (Bowman's capsule): Cup-shaped structure surrounding glomerulus
Glomerulus: Capillary network where filtration occurs; blood enters from afferent arteriole; leave…
Q3: Explain the three stages of urine formation: filtration, reabsorption, and secretion.
Stage 1 - Ultrafiltration (in Bowman's capsule):
• Occurs at glomerulus (capillary network)
• Blood pressure forces small molecules through capillary wall
• Filtered substances: Water, glucose, amino acids, ions, urea (small solutes)
• NOT filtered: Large proteins, blood cells, RBCs (too large)
• Filtrate produced: ~180 liters per day
• Primary filtrate contains useful + waste substances
Stage 2 - Selective reabsorption (in PCT, loop of Henle, DCT):
• Useful substances reabsorbed back into bloo…
Q4: Explain the role of ADH (antidiuretic hormone) in osmoregulation. What happens when ADH is low?
ADH (Antidiuretic hormone) - also called vasopressin:
Production:
• Produced by: Hypothalamus (brain)
• Stored and released by: Posterior pituitary gland
Role in osmoregulation:
1. Increases water reabsorption in kidneys:
• Acts on collecting duct cells
• Increases permeability to water
• More water reabsorbed → more concentrated urine
• Less water in urine → conserves body water
2. Stimulated by:
• Increase in blood osmotic pressure (concentrated blood)
• Dehydration (dete…
Q5: Describe the path of urine from kidney formation to excretion. What is the role of bladder?
Path of urine (from formation to excretion):
1. Formation in nephron:
• Filtration in glomerulus
• Reabsorption in PCT, loop of Henle, DCT
• Secretion in DCT and collecting duct
• Result: Final urine (1-2 liters/day)
2. Collection in renal pelvis:
• Urine flows from collecting ducts → renal pelvis (funnel-shaped)
3. Transport via ureter:
• Ureter (muscular tube) carries urine from kidney to bladder
• Peristalsis (muscular contractions) moves urine downward
• One ureter…
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