10th Class Biology Chapter 11 Notes | Get Now
10th Class Biology Chapter 11 Notes cover Homeostasis, one of the most detailed and diagram-heavy chapters in the Matric Biology syllabus. This chapter explains how the human body and plants maintain stable internal conditions despite changes in the outside environment. These 10th Class Biology Chapter 11 Notes simplify topics like kidney structure, urine formation, osmoregulation, and dialysis for quick and effective revision.
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Homeostasis is a concept that connects biology directly to human health, making it a favorite topic for board examiners. These 10th Class Biology Chapter 11 Notes are organized to help students understand every process — from plant excretion to kidney failure and transplant — in a simple, structured way.
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What This Chapter Covers
Chapter 11 of 10th Class Biology, titled “Homeostasis,” includes:
- Definition and types of homeostasis
- Excretion and osmotic adjustments in plants
- Role of skin in homeostasis
- Human urinary system and kidney structure
- Nephron structure and urine formation
- Osmoregulation
- Kidney stones, kidney failure, dialysis, and transplant
What Is Homeostasis?
Homeostasis is the maintenance of the internal conditions of the body at equilibrium, despite changes in the external environment. This definition is one of the most important lines in the entire chapter and frequently appears in exams.
Examples of Homeostasis
- Body Temperature: The human body stays around 37°C regardless of outside temperature changes
- Blood Glucose Level: Blood glucose remains about 1g per litre even after eating carbohydrate-rich meals
Types of Homeostasis
According to these 10th Class Biology Chapter 11 Notes, there are three main types of homeostasis:
- Osmoregulation – maintaining the amount of water and salts in body fluids
- Thermoregulation – maintaining internal body temperature
- Excretion – removing metabolic wastes to keep internal conditions stable
Homeostasis in Plants
Plants also maintain internal balance, though they lack specialized organs. This section of the 10th Class Biology Chapter 11 Notes explains how plants manage waste and water.
Removal of Extra Carbon Dioxide and Oxygen
- During the day, carbon dioxide produced in respiration is reused in photosynthesis
- At night, surplus carbon dioxide escapes through stomata or root surfaces
- Oxygen produced during photosynthesis is released as a by-product through stomata
Removal of Extra Water
Plants remove excess water through transpiration — the loss of water from plant surfaces in the form of vapours. Another process, guttation, is the appearance of water drops on leaf tips or edges, mostly seen at night in plants like grasses.
| Feature | Transpiration | Guttation |
|---|---|---|
| Time | Day time | Night time |
| Types | Stomatal, cuticular, lenticular | No sub-types |
| Occurs in | All plants | Some grasses |
Removal of Metabolic Wastes in Plants
Plants store harmless metabolic wastes in their tissues, including:
- Calcium oxalate – found in tomato leaves and stems
- Resins – waste product of coniferous trees
- Gums – produced by keekar
- Latex – waste product of rubber plants
- Mucilage – found in carnivorous plants and lady finger
These wastes are often removed permanently during leaf fall in deciduous trees.
Osmotic Adjustments in Plants
Plants are classified into three groups based on water and salt availability:
Hydrophytes – live submerged in freshwater (e.g., water lily), with broad leaves and many stomata to release extra water.
Xerophytes – live in dry environments (e.g., cacti), with thick cuticles, fewer stomata, deep roots, and succulent water-storing stems.
Halophytes – live in salty sea water (e.g., sea grasses), storing salt in vacuoles through active transport to prevent water loss.
Role of Skin in Homeostasis
Skin plays a major role in temperature regulation and waste removal, and this topic is a common long question in board exams.
Structure of Skin
- Epidermis: Outer protective layer without blood vessels
- Dermis: Inner layer containing blood vessels, nerve endings, sweat glands, oil glands, hairs, and fat cells
Functions of Skin
- Insulation: Fat cells in the dermis insulate the body; muscle contraction around hairs creates goosebumps for warmth
- Cooling: Sweat glands release sweat, which cools the body through evaporation
- Waste Removal: Sweat removes excess water, salts, urea, and uric acid
Human Urinary System
The human urinary system is central to this chapter and appears in almost every exam paper. These 10th Class Biology Chapter 11 Notes explain its four main parts:
- A pair of kidneys – filter blood to produce urine
- A pair of ureters – carry urine from kidneys to the bladder
- Urinary bladder – temporarily stores urine
- Urethra – carries urine out of the body
Structure of the Kidney
- Dark-red, bean-shaped organs
- Each kidney is 10 cm long, 5 cm wide, and 4 cm thick, weighing about 27 grams
- Located against the back wall of the abdominal cavity, protected by the last two ribs
The kidney consists of five main structures: hilus, renal cortex, renal medulla, renal pyramids, and renal pelvis.
Structure and Function of Nephron
The nephron is the functional unit of the kidney, with over one million nephrons in each kidney. It has two main parts:
Renal Corpuscle
- Glomerulus: A network of capillaries formed from the afferent arteriole
- Bowman’s Capsule: A cup-shaped structure enclosing the glomerulus
Renal Tubule
The renal tubule has three sections: the proximal convoluted tubule, the Loop of Henle, and the distal convoluted tubule, which eventually connects to a collecting duct.
How Urine Is Formed
Urine formation happens in three key steps, an important long question topic in these 10th Class Biology Chapter 11 Notes:
- Pressure Filtration: High blood pressure forces water, salts, glucose, and urea out of glomerular capillaries into Bowman’s capsule, forming glomerular filtrate.
- Selective Re-absorption: About 99% of the filtrate is reabsorbed into the blood through osmosis, diffusion, and active transport.
- Tubular Secretion: Extra ions and wastes are secreted into the filtrate to maintain normal blood pH (7.35–7.45).
The final urine is only about 1% of the originally filtered volume, with an average adult producing around 1.4 litres per day.
Osmoregulation by the Kidney
Osmoregulation is the regulation of water and salt concentration in blood and body fluids. Kidneys manage this by adjusting urine concentration:
- Excess water in body → kidneys form dilute (hypotonic) urine
- Water shortage in body → kidneys form concentrated (hypertonic) urine
This entire process is under hormonal control.
Kidney Disorders
Kidney Stones
Kidney stones form when urine becomes too concentrated, creating crystals of calcium oxalate, calcium phosphate, ammonium phosphate, or uric acid. Common causes include low water intake, urinary infections, and certain diets. Treatment options include increased water intake, surgery, or lithotripsy (using shock waves to break stones).
Kidney Failure
Kidney failure is the complete or partial failure of the kidney to function, mainly caused by diabetes mellitus and hypertension. Symptoms include vomiting, swelling, high urea levels, and frequent urination.
Treatment of Kidney Failure
Dialysis – the artificial cleaning of blood, done through two methods:
- Peritoneal Dialysis: Dialysis fluid is pumped into the peritoneal cavity to absorb waste
- Haemodialysis: Blood is pumped through a dialyzer machine three times a week
Kidney Transplant – replacing a damaged kidney with a healthy donor kidney, with an average lifetime of 10 to 15 years.
For more chapter-wise resources, visit [internal link] to explore complete 10th Class Biology notes on TaleemWorld.com.
Why These Notes Matter for Exam Preparation
These 10th Class Biology Chapter 11 Notes are structured to match the board exam pattern, covering MCQs, short questions, and long questions on homeostasis, plant excretion, and the human urinary system. Diagrams like the nephron structure, kidney anatomy, and dialysis process are especially valuable since they are frequently asked in practical exams.
Students should also remember historical contributions from Abu Nasr al-Farabi and Abu al-Qasim al-Zahrawi, as these are commonly tested short questions in this chapter.
FAQs
Q1. What topics are covered in 10th Class Biology Chapter 11 Notes?
These notes cover homeostasis, osmoregulation, thermoregulation, excretion in plants, the human urinary system, kidney structure, nephron function, urine formation, kidney stones, dialysis, and kidney transplant.
Q2. What are the three types of homeostasis?
The three types are osmoregulation (water and salt balance), thermoregulation (temperature control), and excretion (removal of metabolic wastes). Together, they help the body maintain stable internal conditions.
Q3. What are the three steps of urine formation?
Urine formation involves pressure filtration, selective re-absorption, and tubular secretion. These steps occur in the nephron and result in the final urine moving to the collecting ducts and then the renal pelvis.
Q4. What is the difference between transpiration and guttation?
Transpiration is the loss of water vapour from plant surfaces during the day, while guttation is the appearance of water drops on leaf tips or edges, usually occurring at night in certain plants like grasses.
Q5. What are the two methods of dialysis?
The two methods are peritoneal dialysis, where fluid is pumped into the peritoneal cavity, and haemodialysis, where blood is pumped through a dialyzer machine. Both remove waste from the blood artificially.
Q6. What causes kidney stones?
Kidney stones form when urine becomes concentrated, creating crystals of calcium oxalate, calcium phosphate, or uric acid. Causes include low water intake, certain diets, age, and recurring urinary tract infections.