Life Processes is one of the most scoring — and most important — chapters in CBSE Class 10 Science. Nearly every board paper carries direct questions from this chapter, whether it’s a 1-mark MCQ on nephron structure or a 5-mark long-answer question on double circulation. At Convex Classes Jaipur, we’ve seen year after year that students who build a strong conceptual foundation in this chapter score full marks in the Biology section.
This blog gives you complete NCERT Solutions for Class 10 Science Chapter 6 Life Processes, but unlike a typical solutions page, we’ve added deeper theory, exam tips, and common mistakes to avoid — so you don’t just memorise the answer, you actually understand why it’s the answer.
What Are Life Processes? (Concept Overview)
Every living organism, no matter how simple or complex, must perform certain basic functions to stay alive and maintain itself. These are called life processes. The five major life processes covered in this chapter are:
- Nutrition – obtaining and utilising food
- Respiration – breaking down food to release usable energy
- Transportation – movement of substances within the organism
- Excretion – removal of metabolic waste products
- Control and Coordination / Reproduction (briefly touched, covered in detail in later chapters)
A key idea NCERT wants you to understand: maintenance is different from growth. Even an organism that isn’t growing (like an adult human) still needs constant energy just to keep its cells alive — repairing damaged parts, maintaining ion balance across membranes, and replacing worn-out molecules. This baseline energy requirement is what makes life processes “essential” rather than optional.
In-Text Questions Solutions
Q1. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms such as humans?
Answer: Diffusion is a slow process that works efficiently only over very short distances — typically across a single cell membrane. In unicellular organisms like amoeba, the entire cell surface is in contact with the environment, so diffusion alone can supply enough oxygen.
However, in multicellular organisms like humans, most cells are located deep inside the body, far from the body surface. If oxygen had to reach these interior cells purely by diffusion, it would take far too long — much longer than the rate at which cells consume oxygen for respiration. Because the surface area to volume ratio decreases as body size increases, diffusion cannot keep pace with the oxygen demand. This is why complex organisms have evolved specialised respiratory and circulatory systems (lungs, blood, heart) to actively transport oxygen to every cell.
Exam tip (Convex Classes Jaipur): Examiners often add a follow-up — “hence justify the need for a respiratory system.” Always mention surface area-to-volume ratio — this single phrase fetches extra marks in CBSE board evaluation.
Q2. What criteria do we use to decide whether something is alive?
Answer: The most reliable and universally accepted criterion is movement at the molecular level — visible in the form of metabolic reactions occurring inside the body. Since these molecular movements are not directly visible under a microscope in most cases, we typically look for indirect but measurable signs of life such as:
- Respiration (release of energy)
- Nutrition (intake of food/raw materials)
- Growth and repair
- Excretion of waste
- Response to stimuli
A key NCERT insight: even something that looks “non-living” from the outside (like a dormant seed) is alive because molecular movement (respiration at a very slow rate) is happening inside it.
Q3. What are outside raw materials used for by an organism?
Answer: Organisms take in raw materials from outside their body for two main purposes:
- As a source of energy – e.g., food, which is broken down to release energy for various life activities.
- As building blocks for the body – e.g., raw materials needed to build new cells and tissues, repair damaged parts, and support growth (proteins, minerals, water).
For example, plants take in CO₂, water, and minerals; humans take in food (carbohydrates, proteins, fats), oxygen, and water.
Q4. What processes would you consider essential for maintaining life?
Answer: The essential life-maintaining processes are: nutrition, respiration, transportation, and excretion. These four processes work together — nutrition supplies raw material, respiration releases usable energy from that material, transportation carries substances to and from cells, and excretion removes the toxic waste generated during these reactions. Without any one of these, an organism cannot survive.
Chat with Convex Classes Jaipur Get Class 10 Science batch details on WhatsApp Chat Now →Nutrition — Detailed Theory + Solutions (Page 101)
Understanding Nutrition
Nutrition is the process by which an organism obtains and utilises food. Based on how organisms obtain their nutrition, they are broadly classified into two types:
1. Autotrophic Nutrition: Organisms make their own food using simple inorganic substances (CO₂ and water) with the help of sunlight and chlorophyll. Green plants and cyanobacteria are autotrophs. The overall process is called photosynthesis.
2. Heterotrophic Nutrition: Organisms cannot make their own food and depend on other organisms (autotrophs or other heterotrophs). Based on how they obtain and ingest food, heterotrophic nutrition is further divided into:
- Holozoic – ingestion of solid food (e.g., humans, most animals)
- Saprophytic – absorbing nutrients from dead and decaying matter (e.g., fungi like bread mould)
- Parasitic – deriving nutrition from a living host, often harming it (e.g., Cuscuta, tapeworm)
Q1. Differences between autotrophic and heterotrophic nutrition
| Basis | Autotrophic Nutrition | Heterotrophic Nutrition |
|---|---|---|
| Food source | Prepares its own food | Depends on other organisms for food |
| Raw material | CO₂, water, and sunlight | Complex organic substances (from other organisms) |
| Requirement of chlorophyll | Essential | Not required |
| Organisms | Green plants, cyanobacteria | Animals, fungi, most bacteria, humans |
| End location of energy fixation | Energy is fixed from sunlight (solar energy) | Energy is obtained by breaking down organic compounds |
Q2. Where do plants get each of the raw materials required for photosynthesis?
Answer:
| Raw Material | Source |
|---|---|
| Carbon dioxide | Absorbed from atmosphere through stomata present on leaves |
| Water | Absorbed from soil through root hairs, transported via xylem |
| Sunlight | Captured by chlorophyll present in chloroplasts of leaf cells |
| Minerals (e.g., nitrogen) | Absorbed from soil through roots |
Note for board exams: The chemical equation for photosynthesis is often asked directly:
6CO₂ + 6H₂O → (sunlight, chlorophyll) → C₆H₁₂O₆ + 6O₂
Photosynthesis actually occurs in three key steps: (1) absorption of light energy by chlorophyll, (2) conversion of light energy to chemical energy and splitting of water into hydrogen and oxygen, and (3) reduction of carbon dioxide to carbohydrates. All three steps need not occur in light, but the first two definitely require light.
Q3. What is the role of acid in our stomach?
Answer: Hydrochloric acid (HCl) secreted by gastric glands in the stomach performs three crucial roles:
- Creates a strongly acidic medium (pH ~1.5–2) necessary for the enzyme pepsin to become active and break down proteins.
- Converts inactive pepsinogen into active pepsin.
- Kills bacteria and other pathogens that enter the stomach along with food, acting as a defence mechanism.
Q4. What is the function of digestive enzymes?
Answer: Digestive enzymes are biological catalysts that speed up the breakdown of complex, insoluble food molecules into simpler, soluble forms that can be absorbed into the bloodstream. For example: amylase breaks starch into sugars, protease/pepsin breaks proteins into amino acids, and lipase breaks fats into fatty acids and glycerol. Without enzymes, digestion would occur too slowly to sustain the body’s energy needs.
Q5. How is the small intestine designed to absorb digested food?
Answer: The small intestine is highly specialised for absorption:
- Its inner wall has numerous finger-like projections called villi, which greatly increase the surface area for absorption.
- Each villus contains a dense network of blood vessels that quickly carry absorbed nutrients into the bloodstream for distribution to all body cells.
- The extensive length and coiled structure of the small intestine additionally provide more time and surface area for complete absorption.
Respiration — Detailed Theory + Solutions (Page 105)
Understanding Respiration
Respiration is the process of breaking down food (glucose) inside cells to release energy, which is stored in the form of ATP (Adenosine Triphosphate) — the energy currency of the cell. Respiration can occur in two ways:
- Aerobic respiration – in the presence of oxygen, occurring in mitochondria, releasing a large amount of energy (~38 ATP molecules per glucose molecule).
- Anaerobic respiration – in the absence of oxygen, occurring in the cytoplasm, releasing much less energy (~2 ATP molecules per glucose molecule).
The first step common to both types is glycolysis — breakdown of glucose into pyruvate — which always occurs in the cytoplasm.
Q1. What is the advantage of terrestrial organisms having a body designed to use atmospheric oxygen for respiration, in comparison to aquatic organisms which use dissolved oxygen in water?
Answer: The amount of dissolved oxygen in water is far lower than the amount of oxygen present in air (atmospheric oxygen concentration is roughly 20 times higher than that dissolved in water). Terrestrial organisms, by directly using atmospheric oxygen, have access to a much richer and more reliable oxygen supply. This is why aquatic organisms (like fish) need to breathe much faster (using gills to extract dissolved oxygen efficiently), while terrestrial organisms can sustain a comparatively slower breathing rate for the same energy needs.
Q2. What are the different ways in which glucose is oxidised to provide energy in various organisms?
Answer:
- In the presence of oxygen (Aerobic respiration): Glucose → Pyruvate → CO₂ + H₂O + large amount of energy (occurs in mitochondria)
- In the absence of oxygen (Anaerobic respiration):
- In yeast (fermentation): Glucose → Pyruvate → Ethanol + CO₂ + small amount of energy
- In our muscle cells (during vigorous exercise): Glucose → Pyruvate → Lactic acid + small amount of energy (causes muscle cramps)
Q3. How are oxygen and carbon dioxide transported in human beings?
Answer:
- Oxygen transport: Oxygen diffuses from the alveoli of the lungs into the blood, where it binds with haemoglobin present in red blood cells to form oxyhaemoglobin. This is carried to all body tissues, where oxygen is released for cellular respiration.
- Carbon dioxide transport: CO₂ produced during respiration is much more soluble in blood than oxygen. It is mostly transported in dissolved form in plasma (as bicarbonate ions) and partly bound to haemoglobin, and is released into the lungs to be exhaled.
Q4. How are the lungs designed to maximise the area for exchange of gases?
Answer: The lungs contain millions of tiny balloon-like sacs called alveoli. This design maximises gas exchange because:
- Alveoli provide an enormous surface area (roughly equal to the size of a tennis court in humans) for gas exchange.
- Their walls are extremely thin (one cell thick), allowing rapid diffusion of gases.
- Each alveolus is surrounded by an extensive network of blood capillaries, ensuring efficient exchange between air and blood.
Transportation — Detailed Theory + Solutions (Page 110)
Q1. What are the components of the transport system in human beings? What are the functions of these components?
Answer:
| Component | Function |
|---|---|
| Heart | Pumps blood throughout the body, maintaining continuous circulation |
| Blood | Transports oxygen, nutrients, hormones, and waste products to and from cells |
| Blood vessels (arteries, veins, capillaries) | Arteries carry oxygenated blood away from the heart (except pulmonary artery); veins carry deoxygenated blood to the heart (except pulmonary vein); capillaries allow exchange of materials with tissues |
Q2. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Answer: Mammals and birds are warm-blooded (endothermic) animals that need to constantly maintain a high body temperature to support a high metabolic rate. A four-chambered heart with a fully partitioned septum keeps oxygenated and deoxygenated blood completely separate. This ensures the body’s cells receive fully oxygenated blood, allowing for highly efficient respiration and a continuous supply of energy required to maintain body temperature — something a mixed blood supply couldn’t provide as effectively.
Q3. What are the components of the transport system in highly organised plants?
Answer: Plants have two separate vascular tissues:
- Xylem – transports water and dissolved minerals from roots to leaves and other parts (unidirectional, upward).
- Phloem – transports the products of photosynthesis (mainly sucrose) from leaves to storage organs and other growing parts of the plant (bidirectional, using energy).
Q4. How are water and minerals transported in plants?
Answer: Water and minerals absorbed by root hairs enter the xylem vessels of the root. They are transported upward through interconnected xylem vessels and tracheids that form a continuous channel from roots to leaves. This upward movement is driven mainly by transpiration pull — the loss of water vapour from leaf surfaces creates a suction force that pulls water up the xylem, aided by cohesive forces between water molecules.
Q5. How is food transported in plants?
Answer: Food (mainly sucrose) synthesised in leaves is transported through phloem in a process called translocation. Unlike xylem transport, this movement requires energy (ATP) supplied by companion cells. Materials in phloem can move in both upward and downward directions — from the leaves (source) to roots, fruits, or seeds (sink), depending on the plant’s requirement at that time.
Excretion — Detailed Theory + Solutions (Page 112–113)
Understanding Excretion
Excretion is the biological process of removing harmful, nitrogenous metabolic waste products from the body. In humans, this is primarily carried out by the excretory system, consisting of a pair of kidneys, ureters, urinary bladder, and urethra.
Q1. Describe the structure and functioning of nephrons.
Answer: The nephron is the basic structural and functional filtration unit of the kidney. Each kidney contains millions of nephrons. Structure and function:
- Glomerulus: A cluster of fine blood capillaries where blood is filtered under pressure.
- Bowman’s capsule: A cup-shaped structure surrounding the glomerulus that collects the filtrate.
- Renal tubule: A long tubular structure where selective reabsorption takes place — useful substances like glucose, amino acids, salts, and a major portion of water are reabsorbed back into the blood, while urea, uric acid, and excess water pass on as urine.
- The filtered urine from each nephron collects in collecting ducts, which lead to the ureter, and finally to the urinary bladder for temporary storage before being expelled through the urethra.
Q2. What are the methods used by plants to get rid of excretory products?
Answer: Unlike animals, plants do not have a dedicated excretory system. They use different strategies:
- Oxygen (a by-product of photosynthesis) and CO₂ are removed via stomata and general diffusion through the plant surface.
- Excess water is removed through transpiration.
- Some waste products are stored in cellular vacuoles, in leaves that eventually fall off (shedding), or in bark and old xylem tissue that becomes non-functional (heartwood).
- Certain wastes are also stored as resins and gums, particularly in old xylem.
Q3. How is the amount of urine produced regulated?
Answer: Urine volume is regulated primarily based on:
- The amount of excess water present in the body.
- The amount of dissolved waste that the body needs to excrete.
- Hormonal regulation, especially by ADH (antidiuretic hormone), which controls the amount of water reabsorbed by the renal tubules — more ADH means more water reabsorption and less urine, and vice versa.
NCERT Textbook Exercise Solutions (Page 113)
1. The kidneys in human beings are a part of the system for (c) excretion
2. The xylem in plants is responsible for (a) transport of water
3. The autotrophic mode of nutrition requires (d) all of the above (carbon dioxide, water, and chlorophyll)
4. The breakdown of pyruvate to give carbon dioxide, water, and energy takes place in (b) mitochondria
5. How are fats digested in our bodies? Where does this process take place?
Answer: Fats enter the small intestine as large globules, which are not directly water-soluble. Bile salts, secreted by the liver, first emulsify the fat — breaking large fat globules into smaller droplets, thus increasing the surface area for enzyme action. Then, lipase enzymes secreted by the pancreas break down the emulsified fats into fatty acids and glycerol. This entire process occurs in the small intestine.
6. What is the role of saliva in the digestion of food?
Answer: Saliva, secreted by salivary glands, contains the enzyme salivary amylase, which breaks down starch into simpler sugars (maltose) in the mouth itself. Saliva also moistens food, making it easier to chew and swallow (forming a bolus).
7. What are the necessary conditions for autotrophic nutrition and what are its by-products?
Answer: Necessary conditions: sunlight, chlorophyll, carbon dioxide, and water. By-products: oxygen (released during the light reaction) and glucose/carbohydrates (the food produced), part of which is stored as starch.
8. Compare aerobic and anaerobic respiration.
| Basis | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen requirement | Occurs in presence of oxygen | Occurs in absence of oxygen |
| Site | Mitochondria (after glycolysis in cytoplasm) | Cytoplasm only |
| End products | CO₂, water, energy | Ethanol + CO₂ (yeast) or lactic acid (muscles) |
| Energy released | Large amount (~38 ATP) | Small amount (~2 ATP) |
| Examples | Humans, most animals and plants | Yeast (fermentation), muscle cells during vigorous exercise |
9. How are alveoli designed to maximise the exchange of gases?
Answer: Alveoli are tiny, thin-walled, balloon-like air sacs present at the end of bronchioles in the lungs. Their design maximises gas exchange because they: (a) provide an enormous surface area due to their sheer number, (b) have walls only one cell thick, minimising diffusion distance, and (c) are richly supplied with a network of blood capillaries, allowing efficient and rapid exchange of oxygen and carbon dioxide between air and blood.
10. What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer: Haemoglobin is the pigment in red blood cells responsible for carrying oxygen. A deficiency of haemoglobin (a condition called anaemia) reduces the blood’s oxygen-carrying capacity. This results in insufficient oxygen supply to body tissues, leading to symptoms such as fatigue, weakness, breathlessness, pale skin, and reduced stamina, since cells cannot generate enough energy through aerobic respiration.
11. Describe double circulation of blood in human beings. Why is it necessary?
Answer: In double circulation, blood passes through the heart twice in one complete cycle:
- Pulmonary circulation: Deoxygenated blood from the body enters the right atrium → right ventricle → pumped to the lungs via the pulmonary artery → oxygenated in the lungs → returns to the left atrium via the pulmonary vein.
- Systemic circulation: Oxygenated blood from the left atrium → left ventricle → pumped to the entire body via the aorta → after delivering oxygen, deoxygenated blood returns to the right atrium via the vena cava.
Why necessary: Double circulation ensures that oxygenated and deoxygenated blood do not mix, allowing highly efficient delivery of oxygen to tissues. This efficient oxygen supply is essential to maintain the high metabolic rate needed by warm-blooded animals like humans to keep a constant body temperature.
12. What are the differences in the transport of materials in xylem and phloem?
| Basis | Xylem | Phloem |
|---|---|---|
| Materials transported | Water and minerals | Food (mainly sucrose) |
| Direction of transport | Unidirectional (upward, roots to leaves) | Bidirectional (source to sink) |
| Energy requirement | Passive process (no ATP used) | Active process (requires ATP) |
| Driving force | Transpiration pull, root pressure | Osmotic pressure gradient created by companion cells |
13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.
| Basis | Alveoli | Nephrons |
|---|---|---|
| Location | Lungs | Kidneys |
| Function | Exchange of oxygen and carbon dioxide | Filtration of blood and formation of urine |
| Structure | Thin-walled, balloon-shaped sac surrounded by capillaries | Long, coiled tubular structure with glomerulus and Bowman’s capsule |
| Common feature | Both provide a large surface area and are richly supplied with blood capillaries to carry out efficient exchange/filtration |
Life Processes Class 10 – Quick Revision Notes
- Nutrition = autotrophic (self-made food via photosynthesis) + heterotrophic (holozoic, saprophytic, parasitic)
- Respiration = aerobic (mitochondria, more energy) vs anaerobic (cytoplasm, less energy)
- Transportation in humans = heart + blood + blood vessels; double circulation keeps oxygenated and deoxygenated blood separate
- Transportation in plants = xylem (water/minerals, upward) + phloem (food, bidirectional)
- Excretion in humans = kidneys → nephrons → ureters → bladder → urethra
- Excretion in plants = transpiration, shedding of leaves, storage in vacuoles/old xylem
Frequently Asked Questions (FAQs)
Q1. What are the five life processes covered in Class 10 Science Chapter 6?
Ans. The chapter primarily covers nutrition, respiration, transportation, and excretion in detail, while briefly introducing control & coordination and reproduction as processes essential to sustaining life.
Q2. Is Chapter 6 Life Processes important for CBSE Class 10 board exams?
Ans. Yes, this is one of the highest-weightage chapters in Class 10 Biology. Diagram-based questions on nephron, alveoli, and the human heart, along with theory questions on nutrition and respiration types, appear almost every year.
Q3. How can Convex Classes Jaipur help me prepare Life Processes better?
Ans. At Convex Classes Jaipur, our Class 10 Science faculty provide concept-based teaching, labelled diagram practice, chapter-wise tests, and doubt-solving sessions specifically designed around the CBSE marking scheme, helping students convert conceptual clarity into board exam marks.
Q4. What is the difference between excretion in plants and animals?
Ans. Animals have a dedicated excretory system (like kidneys) to remove nitrogenous waste, while plants use simpler methods such as diffusion through stomata, transpiration, shedding of leaves, and storage of waste in vacuoles or old tissues.
Q5. Which diagrams are most important from this chapter for exams?
Ans. The human alveoli, nephron structure, human heart (double circulation), and human digestive system are the most frequently asked diagrams in CBSE board papers.
Need More Help with Class 10 Science?
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This content has been prepared by the academic team at Convex Classes Jaipur for educational purposes, strictly following the CBSE/NCERT Class 10 Science syllabus.
