Class 10th Science Chapter 5 – Life Processes | Excretion in Plants and Animals

🧪 Life Processes – Excretion

Excretion in Plants and Animals | Class 10 Science | CBSE + Foundation + Competitive

🧪 Excretion in Plants and Animals

🔬 Animated Diagram – Human Excretory System

Animated Flow:
🩸 Blood → Kidneys → Filtration → Urine → Ureters → Urinary Bladder → Urethra → बाहर

1. What is Excretion? – उत्सर्जन क्या है?

English:
Excretion is the process by which organisms remove metabolic waste products from their bodies.

हिन्दी:
उत्सर्जन वह प्रक्रिया है जिसके द्वारा जीव अपने शरीर से उपापचयी अपशिष्ट पदार्थों को बाहर निकालते हैं।

Important: Excretion is different from egestion.

Excretion: Removal of metabolic wastes.
Egestion: Removal of undigested food.

2. Major Metabolic Wastes

Waste	Main Source
Carbon dioxide	Cellular respiration
Water	Metabolic reactions and excess intake
Urea	Protein metabolism
Uric acid	Nitrogen metabolism
Excess salts	Diet and metabolism

3. Excretion in Plants – पौधों में उत्सर्जन

Plants do not have specialised excretory organs like kidneys. They remove or store wastes in several ways.

पौधों में:

• Oxygen produced during photosynthesis may be released through stomata.
• Carbon dioxide produced during respiration may diffuse out.
• Excess water is lost through transpiration.
• Some wastes are stored in vacuoles.
• Wastes may accumulate in leaves, bark and old tissues.
• Some substances are released as resins, gums and latex.

4. Methods of Excretion in Plants

Method	Example / Explanation
Diffusion	CO₂ and O₂ may move through stomata.
Transpiration	Loss of excess water as water vapour.
Storage	Wastes may be stored in vacuoles or old tissues.
Secretion	Resins, gums and latex may be released.
Leaf fall	Stored wastes may be removed when leaves fall.

5. Excretion in Animals

Different animals use different structures for removal of wastes.

Examples:

• Unicellular organisms – diffusion
• Earthworm – nephridia
• Insects – Malpighian tubules
• Humans – kidneys

6. Human Excretory System

The human excretory system consists mainly of:

1. Two kidneys
2. Two ureters
3. Urinary bladder
4. Urethra

The kidneys filter blood and help form urine.

7. Kidneys – वृक्क

Kidneys are bean-shaped organs located in the abdominal region. Their major functions include:

• Removal of nitrogenous wastes.
• Removal of excess water.
• Removal of excess salts.
• Maintenance of water and salt balance.
• Maintenance of internal chemical balance.

8. Nephron – Structural and Functional Unit

Nephron is the structural and functional unit of the kidney. Each kidney contains a large number of nephrons. A nephron consists mainly of:

• Glomerulus
• Bowman's capsule
• Renal tubule
• Collecting duct

9. Animated Nephron Flow

10. Ultrafiltration – निस्यंदन

Blood enters the glomerulus under pressure. Small molecules such as water, salts, glucose, amino acids and urea are filtered into Bowman's capsule. Large proteins and blood cells normally remain in the blood.

11. Selective Reabsorption

The filtrate passes through the renal tubule. Useful substances are selectively reabsorbed into the blood. These include appropriate amounts of:

• Glucose
• Amino acids
• Water
• Salts

The amount reabsorbed depends on the body's requirements.

12. Urine Formation

Urine Formation = Filtration + Selective Reabsorption + Tubular Secretion

Urine mainly contains:

• Water
• Urea
• Uric acid
• Creatinine
• Excess salts

13. Pathway of Urine

Nephron → Collecting Duct → Ureter → Urinary Bladder → Urethra → Outside

14. Ureter

The two ureters are narrow muscular tubes that carry urine from the kidneys to the urinary bladder. Urine moves through ureters mainly by muscular contractions called peristalsis.

15. Urinary Bladder

The urinary bladder temporarily stores urine. When the bladder becomes sufficiently full, the urge to urinate is generated.

16. Urethra

The urethra is the tube through which urine is expelled from the urinary bladder to the outside of the body.

17. Kidney and Water Balance

Kidneys help regulate the amount of water and salts in the body. When the body has excess water, more dilute urine may be produced. When water needs to be conserved, more water is reabsorbed and urine becomes more concentrated.

18. Dialysis – कृत्रिम रक्त शोधन

When kidneys fail to perform adequate filtration, dialysis may be used to remove certain wastes and excess substances from the blood. A dialysis machine uses a semipermeable membrane and dialysis fluid to assist in removing wastes.

Exam Point: Dialysis is not a normal function of a healthy kidney; it is a medical treatment used when kidney function is severely impaired.

19. Excretion vs Egestion

Excretion	Egestion
Removal of metabolic wastes.	Removal of undigested food.
Kidneys, lungs and skin may participate.	Digestive tract is involved.
Example: urea in urine.	Example: faeces.

20. Other Excretory Organs in Humans

Lungs: Remove carbon dioxide and water vapour.

Skin: Sweat removes water, salts and small amounts of urea.

Kidneys: Remove urea, excess salts and excess water through urine.

21. Excretion in Plants vs Animals

Plants	Animals
No specialised excretory system.	Often have specialised excretory organs.
Wastes may be stored.	Wastes are actively transported and removed.
Stomata, leaves, resins, gums etc.	Kidneys, lungs, skin etc.
Old tissues may accumulate wastes.	Metabolic wastes are continuously removed.

22. 30 MCQs – Multiple Choice Questions

Q1. Excretion is the removal of:

A) Metabolic wastes

B) Undigested food

C) Food from stomach

D) Saliva

Answer: A) Metabolic wastes

Q2. The main excretory organ in humans is:

A) Heart

B) Kidney

C) Stomach

D) Brain

Answer: B) Kidney

Q3. Structural and functional unit of kidney is:

A) Alveolus

B) Neuron

C) Nephron

D) Villus

Answer: C) Nephron

Q4. Urine is stored in:

A) Kidney

B) Ureter

C) Nephron

D) Urinary bladder

Answer: D) Urinary bladder

Q5. Urine is carried from kidney to bladder by:

A) Ureter

B) Urethra

C) Aorta

D) Vein

Answer: A) Ureter

Q6. Urine leaves the body through:

A) Ureter

B) Urethra

C) Kidney

D) Nephron

Answer: B) Urethra

Q7. Urea is mainly formed from metabolism of:

A) Fats

B) Carbohydrates

C) Proteins

D) Vitamins

Answer: C) Proteins

Q8. Filtration of blood in nephron occurs mainly at:

A) Ureter

B) Bladder

C) Urethra

D) Glomerulus

Answer: D) Glomerulus

Q9. Glomerulus is enclosed by:

A) Bowman's capsule

B) Ureter

C) Bladder

D) Urethra

Answer: A) Bowman's capsule

Q10. Selective reabsorption mainly occurs in:

A) Bladder

B) Renal tubule

C) Ureter

D) Urethra

Answer: B) Renal tubule

Q11. Which substance is normally useful and reabsorbed?

A) Urea

B) Creatinine

C) Glucose

D) Excess salt

Answer: C) Glucose

Q12. Plants remove excess water mainly through:

A) Digestion

B) Respiration

C) Circulation

D) Transpiration

Answer: D) Transpiration

Q13. Which gas may be released by plants during photosynthesis?

A) Oxygen

B) Nitrogen

C) Methane

D) Hydrogen

Answer: A) Oxygen

Q14. Which structures help gaseous exchange in leaves?

A) Nephrons

B) Stomata

C) Ureters

D) Villi

Answer: B) Stomata

Q15. Which is NOT normally a component of urine?

A) Urea

B) Water

C) Large amount of glucose

D) Salts

Answer: C) Large amount of glucose

Q16. Dialysis is associated with:

A) Lung failure only

B) Heart digestion

C) Photosynthesis

D) Kidney failure

Answer: D) Kidney failure

Q17. Which organ removes CO₂ as an excretory product?

A) Lungs

B) Kidney

C) Stomach

D) Small intestine

Answer: A) Lungs

Q18. Sweat contains mainly:

A) Only proteins

B) Water and salts

C) Only glucose

D) Starch

Answer: B) Water and salts

Q19. Earthworms excrete through:

A) Kidneys

B) Malpighian tubules

C) Nephridia

D) Lungs

Answer: C) Nephridia

Q20. Insects excrete mainly through:

A) Kidneys

B) Nephridia

C) Gills

D) Malpighian tubules

Answer: D) Malpighian tubules

Q21. Removal of undigested food is called:

A) Egestion

B) Excretion

C) Filtration

D) Reabsorption

Answer: A) Egestion

Q22. The urinary bladder mainly:

A) Filters blood

B) Stores urine

C) Produces urea

D) Absorbs oxygen

Answer: B) Stores urine

Q23. Which process removes useful substances from filtrate back to blood?

A) Digestion

B) Respiration

C) Selective reabsorption

D) Egestion

Answer: C) Selective reabsorption

Q24. Plants can store wastes in:

A) Blood

B) Nephrons

C) Alveoli

D) Vacuoles

Answer: D) Vacuoles

Q25. Resins and gums are examples of:

A) Plant excretory products

B) Digestive enzymes

C) Blood cells

D) Hormones

Answer: A) Plant excretory products

Q26. Which structure carries urine out of the body?

A) Ureter

B) Urethra

C) Kidney

D) Glomerulus

Answer: B) Urethra

Q27. The main nitrogenous waste in human urine is:

A) Glucose

B) Starch

C) Urea

D) Oxygen

Answer: C) Urea

Q28. The first major step in urine formation is:

A) Egestion

B) Digestion

C) Respiration

D) Filtration

Answer: D) Filtration

Q29. Kidney helps maintain:

A) Water and salt balance

B) Only body temperature

C) Only digestion

D) Only respiration

Answer: A) Water and salt balance

Q30. Which sequence is correct?

A) Bladder → Kidney → Ureter → Urethra

B) Kidney → Ureter → Bladder → Urethra

C) Urethra → Kidney → Bladder → Ureter

D) Kidney → Bladder → Ureter → Urethra

Answer: B) Kidney → Ureter → Bladder → Urethra

23. 30 Subjective Questions with Answers

1 Mark Q1. What is excretion?

Answer: Excretion is the removal of metabolic wastes from the body.

1 Mark Q2. Name the structural and functional unit of kidney.

Answer: Nephron.

1 Mark Q3. Name the main nitrogenous waste in humans.

Answer: Urea.

1 Mark Q4. Where is urine stored?

Answer: Urinary bladder.

1 Mark Q5. What is egestion?

Answer: Egestion is the removal of undigested food from the digestive tract.

1 Mark Q6. Name one excretory product of plants.

Answer: Oxygen, carbon dioxide, excess water, resin, gum or latex.

2 Marks Q7. Name the main parts of the human excretory system.

Answer: Two kidneys, two ureters, urinary bladder and urethra.

2 Marks Q8. What is the function of kidneys?

Answer: Kidneys filter blood and remove nitrogenous wastes, excess water and salts in the form of urine.

2 Marks Q9. Differentiate between excretion and egestion.

Answer: Excretion removes metabolic wastes such as urea. Egestion removes undigested food as faeces.

2 Marks Q10. What is selective reabsorption?

Answer: It is the process in which useful substances such as glucose, amino acids, water and required salts are reabsorbed from the filtrate into the blood.

2 Marks Q11. What is dialysis?

Answer: Dialysis is a medical procedure that helps remove wastes and excess substances from blood when kidneys cannot perform adequate filtration.

2 Marks Q12. How do plants remove excess water?

Answer: Plants mainly lose excess water through transpiration, especially through stomata.

3 Marks Q13. Explain the structure of a nephron.

Answer: A nephron consists of a glomerulus enclosed by Bowman's capsule, followed by a renal tubule and collecting duct. It is the structural and functional unit of the kidney.

3 Marks Q14. Explain ultrafiltration.

Answer: Blood enters the glomerulus under pressure. Small molecules such as water, salts, glucose, amino acids and urea are filtered into Bowman's capsule, while blood cells and large proteins generally remain in the blood.

3 Marks Q15. Explain selective reabsorption.

Answer: As filtrate passes through the renal tubule, useful substances are selectively taken back into the blood according to the body's requirements.

3 Marks Q16. How do plants excrete gaseous wastes?

Answer: Gaseous wastes such as oxygen from photosynthesis and carbon dioxide from respiration can diffuse through stomata and other gas-exchange surfaces.

3 Marks Q17. Mention three ways by which plants remove or store wastes.

Answer: Plants can remove wastes by diffusion, transpiration and secretion, and can also store wastes in vacuoles, leaves, bark or old tissues.

3 Marks Q18. State the role of lungs and skin in excretion.

Answer: Lungs remove carbon dioxide and water vapour. Skin removes water, salts and small amounts of urea through sweat.

4 Marks Q19. Describe the human excretory system.

Answer: The human excretory system consists of two kidneys, two ureters, a urinary bladder and a urethra. Kidneys filter blood and form urine. Ureters carry urine to the bladder, where it is stored. Urethra carries urine outside the body.

4 Marks Q20. Explain the process of urine formation.

Answer: Urine formation involves:

1. Filtration of blood at the glomerulus.
2. Formation of filtrate in Bowman's capsule.
3. Selective reabsorption of useful substances.
4. Collection and removal of remaining waste as urine.

4 Marks Q21. Explain how plants deal with their waste products.

Answer: Plants release gaseous wastes by diffusion, lose excess water by transpiration, store wastes in vacuoles and old tissues, and may release substances such as gums, resins and latex.

4 Marks Q22. Why do animals require specialised excretory organs?

Answer: Animals have active metabolism and produce wastes that may become harmful if accumulated. Specialised organs help efficiently remove these wastes and maintain water and salt balance.

5 Marks Q23. Explain the role of nephron in urine formation.

Answer: The nephron filters blood at the glomerulus. The filtrate enters Bowman's capsule and passes through the renal tubule. Useful substances such as glucose, amino acids, water and required salts are selectively reabsorbed. The remaining fluid containing wastes forms urine and passes into the collecting duct.

5 Marks Q24. Explain the pathway of urine from kidney to outside the body.

Answer:
Kidney/Nephrons → Collecting ducts → Ureters → Urinary bladder → Urethra → Outside body.

The bladder temporarily stores urine before it is expelled.

5 Marks Q25. Differentiate between excretion in plants and animals.

Plants	Animals
No specialised excretory system.	Specialised excretory organs may be present.
Wastes may be stored.	Wastes are generally removed actively.
Stomata, leaves, gums, resins etc.	Kidneys, lungs, skin etc.

5 Marks Q26. Explain how kidneys maintain water and salt balance.

Answer: Kidneys filter blood and selectively reabsorb water and salts according to the body's requirements. Excess water and salts are removed in urine, helping maintain the internal balance of the body.

6 Marks Q27. Describe the complete process of urine formation.

Answer:

1. Blood enters the glomerulus.
2. High pressure causes filtration of small molecules.
3. Filtrate enters Bowman's capsule.
4. Useful substances are selectively reabsorbed by the renal tubule.
5. Additional substances may be secreted into the tubule.
6. The remaining fluid forms urine and passes through the collecting duct.

6 Marks Q28. Explain the role of kidneys, lungs and skin in human excretion.

Answer:

• Kidneys: Remove urea, excess salts and excess water.
• Lungs: Remove carbon dioxide and water vapour.
• Skin: Removes water, salts and small amounts of urea through sweat.

Together these organs help maintain internal balance.

6 Marks Q29. Explain different methods of excretion in plants.

Answer: Plants remove wastes by:

• Diffusion through stomata.
• Loss of excess water through transpiration.
• Storage of wastes in vacuoles.
• Accumulation in leaves, bark and old tissues.
• Removal through falling leaves.
• Secretion of gums, resins and latex.

6 Marks Q30. Explain the human excretory system with the functions of its major parts.

Answer: The human excretory system consists of two kidneys, two ureters, urinary bladder and urethra.

Kidneys: Filter blood and form urine.
Ureters: Carry urine from kidneys to bladder.
Urinary bladder: Stores urine temporarily.
Urethra: Carries urine outside the body.

The nephron inside the kidney performs filtration and selective reabsorption during urine formation.

24. HOTS / Application Based Questions

HOTS 1: Why does a healthy person normally not have a large amount of glucose in urine?

Answer: Glucose is a useful substance and is normally selectively reabsorbed from the filtrate back into the blood.

HOTS 2: Why does urine become more concentrated when the body needs to conserve water?

Answer: More water is reabsorbed from the renal tubules, leaving a smaller volume of urine containing relatively more dissolved wastes.

HOTS 3: Why can plants survive without kidneys?

Answer: Plants have a different metabolic organisation and can remove, diffuse, store or isolate wastes through several structures rather than using a specialised kidney-like organ.

HOTS 4: What may happen if nitrogenous wastes accumulate in the body?

Answer: Nitrogenous wastes can become toxic and disturb normal cellular functions. Therefore, efficient excretion is essential.

25. CBSE Golden Points ⭐

• Excretion = removal of metabolic wastes.
• Egestion = removal of undigested food.
• Kidney is the main excretory organ in humans.
• Nephron is the structural and functional unit of kidney.
• Glomerulus performs filtration.
• Bowman's capsule collects the filtrate.
• Renal tubule performs selective reabsorption.
• Ureter carries urine to urinary bladder.
• Urinary bladder stores urine.
• Urethra carries urine outside.
• Urea is the major nitrogenous waste in human urine.
• Lungs remove CO₂ and water vapour.
• Skin removes water, salts and small amounts of urea.
• Plants have no specialised excretory system like kidneys.
• Plants can remove wastes by diffusion and transpiration.
• Plants may store wastes in vacuoles and old tissues.
• Gums, resins and latex are examples of plant secretions.
• Dialysis is used when kidney function is severely impaired.

26. Quick Revision – एक नजर में

🩸 Blood → Glomerulus → Filtration → Bowman's Capsule → Renal Tubule → Selective Reabsorption → Collecting Duct → Urine

Urine → Ureter → Urinary Bladder → Urethra → Outside

🌱 Plants: Diffusion + Transpiration + Storage + Secretion

⭐ Exam Mantra:

Kidney → Filter
Nephron → Functional Unit
Glomerulus → Filtration
Renal Tubule → Reabsorption
Ureter → Kidney to Bladder
Urethra → Bladder to Outside
Excretion ≠ Egestion