Life Processes — Class 10 Biology NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 10 Biology chapter "Life Processes" — 9 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 10 Biology chapter "Life Processes" — 9 important questions with detailed answers for CBSE board exam prep…
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
NCERT Solutions for Class 10 Biology — Life Processes. Step-by-step answers to all 9 textbook questions from this chapter, written for CBSE board preparation and free to use.
Life Processes — All 9 Questions Solved
Q1. Define nutrition. Name the two types of nutrition.
Nutrition is the process by which organisms obtain food and use it to grow, produce energy, and repair body tissues.
Two types of nutrition:
1. Autotrophic nutrition - organisms make their own food (e.g., plants, green algae)
2. Heterotrophic nutrition - organisms obtain food from other organisms (e.g., animals, fungi)
Q2. Write the balanced chemical equation for photosynthesis.
6CO2 + 6H2O → C6H12O6 + 6O2
(in the presence of light energy and chlorophyll)
Or in word form:
Carbon dioxide + Water → Glucose + Oxygen
(light is needed for this reaction)
Q3. What are the raw materials and products of photosynthesis? Where do they come from and where do they go?
Raw materials of photosynthesis:
1. Carbon dioxide (CO2) - enters through stomata in leaves
2. Water (H2O) - absorbed by roots from soil
3. Light energy - from the Sun
Products of photosynthesis:
1. Glucose (C6H12O6) - stored as starch in leaves and used for growth and energy
2. Oxygen (O2) - released into atmosphere through stomata
The oxygen is a byproduct that is released into the air. Glucose is used by the plant for respiration and growth.
Q4. Describe the human digestive system and explain the function of each major organ.
The human digestive system is a tube-like structure running from mouth to anus, with accessory organs helping digestion.
Major organs and functions:
1. Mouth - mechanical digestion (chewing) and chemical digestion (salivary amylase breaks down starch)
2. Oesophagus - tube that transports food to stomach by peristalsis
3. Stomach - stores food; gastric juice (HCl and pepsin) digests proteins into peptides
4. Small intestine (duodenum, jejunum, ileum) - main site of digestion and absorption; receives bile from liver and pancreatic juice containing enzymes; villi absorb glucose, amino acids, and fats
5. Large intestine (colon) - absorbs water and minerals; forms faeces
6. Rectum and anus - expels faeces
Accessory organs:
- Salivary glands - produce saliva with amylase
- Liver - produces bile to emulsify fats
- Pancreas - produces enzymes (amylase, protease, lipase) and bicarbonate
Q5. Write the equation for aerobic respiration and explain where it occurs in the cell.
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP)
Or in word form:
Glucose + Oxygen → Carbon dioxide + Water + Energy
Location in the cell:
- Glycolysis occurs in the cytoplasm (glucose is broken down into pyruvate, releasing some energy)
- Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix
- Electron transport chain occurs on the inner mitochondrial membrane
Mitochondria is called the powerhouse of the cell because most ATP is produced there through aerobic respiration.
Q6. Compare aerobic and anaerobic respiration.
Aerobic respiration:
- Uses oxygen
- Occurs in mitochondria
- Glucose completely oxidized to CO2 and H2O
- Produces 38 ATP molecules per glucose
- Products: CO2, water, energy
- Examples: most animal and plant cells
Anaerobic respiration:
- Does not use oxygen
- Occurs in cytoplasm
- Glucose partially broken down
- Produces only 2 ATP molecules per glucose
- Products: lactic acid (in animals) or ethanol and CO2 (in plants and yeast)
- Examples: muscle cells during intense exercise, red blood cells, yeast fermentation
Aerobic respiration produces much more energy (ATP) than anaerobic respiration.
Q7. Describe the structure and functions of the human circulatory system.
The human circulatory system transports nutrients, oxygen, hormones, and removes waste products.
Components:
1. Heart - muscular pump that beats continuously
- Right atrium receives deoxygenated blood from body
- Right ventricle pumps blood to lungs
- Left atrium receives oxygenated blood from lungs
- Left ventricle pumps blood to body
2. Blood vessels:
- Arteries - carry blood away from heart under high pressure; elastic walls
- Veins - carry blood towards heart under low pressure; have valves to prevent backflow
- Capillaries - tiny vessels where exchange of gases and nutrients occur
3. Blood - transports oxygen, nutrients, hormones, antibodies, and removes CO2 and urea
Function: Delivers oxygen and nutrients to all cells; removes CO2 and nitrogenous wastes; distributes hormones; maintains body temperature
Q8. What is the structure of a human nephron and how does it filter blood?
A nephron is the functional unit of the kidney. Each kidney has about 1 million nephrons.
Structure of nephron:
1. Bowman's capsule - cup-shaped structure surrounding a glomerulus
2. Glomerulus - network of capillaries for filtration
3. Proximal convoluted tubule - reabsorbs glucose, amino acids, vitamins, ions, and water
4. Loop of Henle - creates concentration gradient; descending limb is permeable to water, ascending limb is permeable to ions
5. Distal convoluted tubule - further reabsorption of ions and water under hormone control
6. Collecting duct - final water reabsorption; drains into ureter
Filtration process:
1. Ultrafiltration in Bowman's capsule - small molecules (glucose, urea, ions, water) filtered from blood; large proteins and blood cells remain
2. Selective reabsorption in tubules - useful substances reabsorbed back into blood
3. Osmoregulation - water reabsorption regulated by ADH hormone
4. Urine formation - remaining urea, excess ions, and water form urine
Q9. Explain how the three systems (digestive, respiratory, circulatory) work together to provide energy to body cells.
Integration of three systems:
1. Digestive system breaks down food:
- Carbohydrates broken to glucose
- Proteins broken to amino acids
- Fats broken to fatty acids and glycerol
2. Circulatory system transports absorbed nutrients:
- Glucose, amino acids, and fats absorbed in small intestine
- Enter blood and circulate to all cells
- Also carries oxygen from lungs to tissues
3. Respiratory system provides oxygen:
- Air enters lungs
- Oxygen diffuses into blood through alveolar walls
- Blood carries oxygen to cells
4. In cells, aerobic respiration occurs:
- Glucose + Oxygen → Energy (ATP) + CO2 + Water
- Energy used for all life activities
5. Circulatory system removes wastes:
- CO2 from cells transported to lungs
- Urea from liver transported to kidneys
- Both removed from body
Thus, digestion provides fuel, respiration provides oxygen, circulation delivers both to cells for energy production.
Life Processes — Practice MCQs with Answers
Attempt these 20 multiple-choice questions after working through the solutions above. Each carries the correct option and the reasoning behind it, so a wrong answer tells you which idea to revisit.
MCQ 1. Which of the following organisms exhibit saprophytic nutrition?
- A. Green plants
- B. Amoeba
- C. Fungi
- D. Humans
Answer: C. Fungi — Fungi obtain nutrients by decomposing dead organic matter, which is characteristic of saprophytic nutrition.
MCQ 2. During cellular respiration, the complete breakdown of glucose in the presence of oxygen primarily occurs in which cellular organelle?
- A. Cytoplasm
- B. Nucleus
- C. Mitochondria
- D. Ribosomes
Answer: C. Mitochondria — The complete breakdown of glucose into carbon dioxide and water, generating a large amount of ATP, occurs in the mitochondria during aerobic respiration.
MCQ 3. Which of the following statements correctly describes the function of lymph in the human body?
- A. It transports oxygen to the tissues.
- B. It helps in the absorption of fats from the intestine.
- C. It carries carbon dioxide from tissues to the lungs.
- D. It forms a barrier against pathogens by producing antibodies.
Answer: B. It helps in the absorption of fats from the intestine. — Lymph, specifically through lacteals in the small intestine, plays a crucial role in absorbing digested fats and fat-soluble vitamins.
MCQ 4. The functional unit of the kidney is the:
- A. Neuron
- B. Alveolus
- C. Nephron
- D. Villi
Answer: C. Nephron — The nephron is the microscopic structural and functional unit of the kidney that filters blood and produces urine.
MCQ 5. The primary function of bile juice secreted by the liver is to:
- A. Digest proteins in the stomach.
- B. Emulsify fats in the small intestine.
- C. Break down carbohydrates in the mouth.
- D. Absorb water in the large intestine.
Answer: B. Emulsify fats in the small intestine. — Bile juice helps in the emulsification of fats, breaking large fat globules into smaller ones, which increases the surface area for lipase action.
MCQ 6. What is the main energy currency of the cell?
- A. DNA
- B. RNA
- C. ATP
- D. Glucose
Answer: C. ATP — ATP (Adenosine Triphosphate) is the molecule that stores and transfers energy within cells, acting as the immediate energy source for most cellular activities.
MCQ 7. In a healthy adult human, the oxygen-rich blood flows from the lungs into which chamber of the heart first?
- A. Right Atrium
- B. Left Atrium
- C. Right Ventricle
- D. Left Ventricle
Answer: B. Left Atrium — Oxygenated blood from the lungs enters the left atrium via the pulmonary veins.
MCQ 8. Identify the correct sequence of events that occur during photosynthesis.
- A. I. Absorption of light energy by chlorophyll. II. Conversion of light energy to chemical energy. III. Reduction of carbon dioxide to carbohydrates. IV. Splitting of water molecules into hydrogen and oxygen.
- B. I. Absorption of light energy by chlorophyll. IV. Splitting of water molecules into hydrogen and oxygen. II. Conversion of light energy to chemical energy. III. Reduction of carbon dioxide to carbohydrates.
- C. IV. Splitting of water molecules into hydrogen and oxygen. I. Absorption of light energy by chlorophyll. II. Conversion of light energy to chemical energy. III. Reduction of carbon dioxide to carbohydrates.
- D. I. Absorption of light energy by chlorophyll. II. Conversion of light energy to chemical energy. IV. Splitting of water molecules into hydrogen and oxygen. III. Reduction of carbon dioxide to carbohydrates.
Answer: B. I. Absorption of light energy by chlorophyll. IV. Splitting of water molecules into hydrogen and oxygen. II. Conversion of light energy to chemical energy. III. Reduction of carbon dioxide to carbohydrates. — Photosynthesis begins with light absorption, followed by water splitting, then light energy conversion to chemical energy, and finally CO2 reduction to carbohydrates.
MCQ 9. Which part of the nephron is responsible for the selective reabsorption of useful substances like glucose, amino acids, salts, and water into the blood?
- A. Glomerulus
- B. Bowman's capsule
- C. Renal artery
- D. Renal tubule (e.g., PCT, Loop of Henle, DCT)
Answer: D. Renal tubule (e.g., PCT, Loop of Henle, DCT) — The renal tubule, specifically parts like the Proximal Convoluted Tubule (PCT), Loop of Henle, and Distal Convoluted Tubule (DCT), is where most selective reabsorption of essential substances occurs.
MCQ 10. Which component of blood is primarily responsible for the transport of oxygen?
- A. Plasma
- B. Platelets
- C. White Blood Cells
- D. Red Blood Cells
Answer: D. Red Blood Cells — Red Blood Cells (erythrocytes) contain hemoglobin, which binds with oxygen and transports it from the lungs to various tissues.
MCQ 11. The process of obtaining food by Amoeba is called:
- A. Diffusion
- B. Photosynthesis
- C. Phagocytosis
- D. Osmosis
Answer: C. Phagocytosis — Amoeba engulfs food particles by forming pseudopodia, a process known as phagocytosis.
MCQ 12. In which of the following scenarios would anaerobic respiration most likely occur in human muscle cells?
- A. During normal breathing and walking.
- B. While resting after a meal.
- C. During intense exercise like sprinting.
- D. When sleeping soundly.
Answer: C. During intense exercise like sprinting. — During intense exercise, when oxygen supply to muscle cells is insufficient to meet energy demands, anaerobic respiration takes place, producing lactic acid.
MCQ 13. What is the primary function of xylem tissue in plants?
- A. Transport of food from leaves to other parts.
- B. Transport of water and minerals from roots to leaves.
- C. Storage of starch.
- D. Providing structural support only.
Answer: B. Transport of water and minerals from roots to leaves. — Xylem tissue is responsible for the unidirectional transport of water and dissolved minerals from the roots upwards to all aerial parts of the plant.
MCQ 14. A patient is diagnosed with kidney failure and undergoes dialysis. Which of the following processes is NOT performed by the artificial kidney (dialyzer) during hemodialysis?
- A. Filtration of nitrogenous wastes from blood.
- B. Reabsorption of essential nutrients like glucose.
- C. Removal of excess salts and water.
- D. Maintaining the correct ionic balance in blood.
Answer: B. Reabsorption of essential nutrients like glucose. — An artificial kidney effectively filters waste products, excess salts, and water, and helps maintain ionic balance, but it cannot perform the selective reabsorption of useful substances like glucose and amino acids, which is a vital function of the renal tubules in a natural kidney.
MCQ 15. The exchange of gases (oxygen and carbon dioxide) in the lungs takes place in which structures?
- A. Bronchi
- B. Trachea
- C. Alveoli
- D. Diaphragm
Answer: C. Alveoli — Alveoli are tiny air sacs in the lungs where the actual exchange of oxygen and carbon dioxide between the air and blood occurs.
MCQ 16. Which of the following describes the correct path of blood flow in a double circulation system, starting from the systemic circulation?
- A. Body -> Right Atrium -> Right Ventricle -> Lungs -> Left Atrium -> Left Ventricle -> Body
- B. Body -> Left Atrium -> Left Ventricle -> Lungs -> Right Atrium -> Right Ventricle -> Body
- C. Lungs -> Left Atrium -> Left Ventricle -> Body -> Right Atrium -> Right Ventricle -> Lungs
- D. Lungs -> Right Atrium -> Right Ventricle -> Body -> Left Atrium -> Left Ventricle -> Lungs
Answer: A. Body -> Right Atrium -> Right Ventricle -> Lungs -> Left Atrium -> Left Ventricle -> Body — Deoxygenated blood from the body enters the right atrium, then right ventricle, which pumps it to the lungs. Oxygenated blood from the lungs enters the left atrium, then left ventricle, which pumps it to the body. This completes one full cycle of double circulation.
MCQ 17. Which of the following is a waste product excreted by plants?
- A. Oxygen
- B. Carbon dioxide
- C. Water vapor
- D. All of the above
Answer: D. All of the above — Plants excrete oxygen during photosynthesis, carbon dioxide during respiration, and excess water vapor through transpiration. Therefore, all listed options are waste products under specific conditions or processes.
MCQ 18. Which of the following is a common pathway for both food and air?
- A. Larynx
- B. Trachea
- C. Pharynx
- D. Esophagus
Answer: C. Pharynx — The pharynx serves as a common passage for both air (from nasal cavity/mouth to larynx) and food (from mouth to esophagus).
MCQ 19. Which blood vessels carry blood away from the heart?
- A. Veins
- B. Arteries
- C. Capillaries
- D. Lymph vessels
Answer: B. Arteries — Arteries are blood vessels that carry oxygenated blood (except pulmonary artery) away from the heart to other parts of the body.
MCQ 20. Stomata are pores found on the surface of leaves. Their main functions include:
- A. Absorption of light and support.
- B. Exchange of gases and transpiration.
- C. Storage of water and minerals.
- D. Synthesis of food and release of hormones.
Answer: B. Exchange of gases and transpiration. — Stomata regulate the exchange of gases (CO2 for photosynthesis, O2 release) and also control the loss of water vapor from the plant through transpiration.
How to Use These Solutions
Attempt each question yourself first and only then compare with the worked answer. Marks in the CBSE board exam are awarded for the METHOD as much as the final result, so reproduce the steps rather than memorising the last line. Where a solution states a law, a formula or a definition, learn that wording — examiners look for it.
Related practice for this chapter: chapter MCQs, previous-year questions, revision notes and sample papers.