Navigating through the CBSE Class 10 Science curriculum requires an in-depth understanding of physiological mechanisms, cellular respiration pathways, vascular transportation, renal filtration, and metabolic regulation. Chapter 5 of Class 10 Biology, “Life Processes”, forms the cornerstone of secondary biological sciences. It explores the four fundamental maintenance processes that sustain living organisms: Nutrition (autotrophic photosynthesis and heterotrophic holozoic digestion), Respiration (aerobic and anaerobic breakdown of glucose), Transportation (double circulation in humans and xylem/phloem translocation in plants), and Excretion (nephron ultrafiltration and plant waste disposal). To help students master every aspect of this high-weightage chapter, this comprehensive solutions guide offers textbook-accurate, highly structured, and pedagogically sound responses strictly aligned with the latest CBSE evaluation standards.
Every question presented in the official NCERT textbook—ranging from all five in-text question sets (Pages 81, 87, 91, 96, and 98) to the complete chapter-end exercises (Questions 1 to 13 on Pages 99–100)—has been solved with exhaustive detail. Short-answer conceptual responses follow the official 30–40 word limit, while 3-mark and 5-mark physiological comparisons use structured tables and clear biochemical equations. Key scoring terms, official CBSE board year tags, and comparative charts have been highlighted to ensure students secure maximum marks in their CBSE Board Examinations.
Master Formula & Concept Summary Tables
1. Differences Between Autotrophic and Heterotrophic Nutrition
| Parameter / Basis | Autotrophic Nutrition | Heterotrophic Nutrition |
|---|---|---|
| Source of Food | Organisms synthesize their own organic food from simple inorganic raw materials (CO₂ and H₂O). | Organisms cannot synthesize food and depend directly or indirectly on autotrophs. |
| Energy Requirement | Solar energy is trapped using chlorophyll pigments for photosynthesis. | Chemical energy is derived by ingesting and digesting organic food. |
| Chlorophyll Pigment | Mandatory and present in chloroplasts. | Absent in heterotrophic organisms. |
| Examples of Organisms | Green plants, cyanobacteria, and autotrophic algae. | Animals, human beings, fungi (yeast, bread mold), and non-green bacteria. |
2. Breakdown of Glucose by Various Pathways
| Pathway / Condition | Site of Occurrence | Intermediate & Final Products | Energy Yield (ATP) |
|---|---|---|---|
| 1. Aerobic Respiration (In presence of O₂) | Mitochondria (after Cytoplasm) | Pyruvate → Carbon Dioxide (CO₂) + Water (H₂O) + Energy | High Energy (36 to 38 ATP molecules per glucose molecule) |
| 2. Anaerobic in Yeast (Fermentation – Absence of O₂) | Cytoplasm | Pyruvate → Ethanol (C₂H₅OH) + Carbon Dioxide (CO₂) + Energy | Low Energy (Only 2 ATP molecules) |
| 3. Anaerobic in Muscle Cells (Lack of O₂ during exercise) | Muscle Cytoplasm | Pyruvate → Lactic Acid (CH₃CHOHCOOH) + Energy | Low Energy (2 ATP; causes muscle cramps) |
3. Comparison: Transport in Xylem vs. Transport in Phloem
| Feature / Property | Xylem Tissue | Phloem Tissue |
|---|---|---|
| Primary Material Transported | Water and dissolved inorganic mineral nutrients. | Organic food (sucrose), amino acids, and plant hormones. |
| Direction of Transport | Unidirectional only (Strictly upward from roots to leaves). | Bidirectional (Upward and downward depending on plant needs). |
| Living vs. Dead Tissue | Consists mostly of dead elements (Tracheids and Vessels). | Consists mostly of living cells (Sieve tubes and Companion cells). |
| Driving Mechanism / Energy | Driven by physical forces (Transpiration Pull and Root Pressure); no ATP required. | Driven by Active Transport using ATP energy and osmotic pressure. |
NCERT In-Text Questions: Set 1 (Page No. 81)
Question 1 Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans? [CBSE 2024, 2020]
Answer: In large multicellular organisms like humans, the body size is vast and all cells are not in direct contact with the surrounding environment.
Simple diffusion is an extremely slow physical process that would take years for oxygen to reach distant tissues like the feet. Therefore, multicellular organisms require specialized respiratory pigments (Haemoglobin) and a dedicated circulatory system to transport oxygen rapidly to every cell.
Question 2 What criteria do we use to decide whether something is alive? [CBSE 2023]
Answer: We use the following key criteria to determine if something is alive:
- Visible Movements: Locomotion, breathing, and growth-related plant movements.
- Invisible Molecular Movements: Continuous biochemical cellular repair and maintenance.
- Fundamental Life Processes: Performance of nutrition, cellular respiration, internal transport, reproduction, and excretion.
Question 3 What are outside raw materials used for by an organism?
Answer: Organisms use outside raw materials for energy, growth, and cellular repair:
- Carbon-based Food (Carbohydrates/Fats): Source of energy and structural carbon.
- Oxygen (O₂): Used for cellular breakdown of food to release ATP energy.
- Water and Mineral Salts: Essential for maintaining cell turgidity, chemical transport, and enzymatic activities.
Question 4 What processes would you consider essential for maintaining life? [BOARD EXAM FAVORITE]
Answer: The four fundamental processes essential for maintaining life are:
- Nutrition: Intake and digestion of food to obtain energy and raw materials.
- Respiration: Breakdown of digested nutrients in cells to liberate usable ATP energy.
- Transportation: Circulation of oxygen, nutrients, and hormones to all body tissues.
- Excretion: Removal of toxic, nitrogenous metabolic waste products from the body.
NCERT In-Text Questions: Set 2 (Page No. 87)
Question 1 What are the differences between autotrophic nutrition and heterotrophic nutrition? [CBSE 2024]
Answer:
- Autotrophic Nutrition: Organisms manufacture their own food from simple inorganic substances like carbon dioxide and water using sunlight and chlorophyll (e.g., green plants).
- Heterotrophic Nutrition: Organisms cannot make their own food and must consume complex organic food synthesized by plants or other animals (e.g., animals, fungi).
Question 2 Where do plants get each of the raw materials required for photosynthesis? [CBSE 2023, 2020]
Answer: Plants obtain their raw materials from the following environmental sources:
- Carbon Dioxide (CO₂): Absorbed from the atmospheric air through microscopic leaf pores called Stomata.
- Water (H₂O): Absorbed from the soil by root hairs through osmosis and transported via Xylem vessels.
- Sunlight: Absorbed directly from the sun by Chlorophyll pigments located in chloroplasts.
- Nitrogen, Phosphorus, Iron & Magnesium: Taken up from the soil dissolved in water.
Question 3 What is the role of the acid in our stomach? [CBSE 2024, 2022]
Answer: Hydrochloric acid (HCl) secreted by the gastric glands serves two vital functions:
- Activation of Enzymes: It creates an acidic medium (pH 1.5 – 3.0) required to activate the inactive enzyme pepsinogen into active Pepsin for protein digestion.
- Germicidal Action: It kills harmful bacteria and pathogens that enter the stomach along with ingested food.
Question 4 What is the function of digestive enzymes? [CBSE 2023]
Answer: Digestive enzymes act as biological catalysts that break down complex, insoluble, and non-absorbable food macromolecules into simple, soluble, and diffusible molecules:
- Salivary Amylase: Converts complex Starch into simple Maltose sugar.
- Pepsin and Trypsin: Break down complex Proteins into Peptides and Amino acids.
- Lipase: Converts emulsified Fats into Fatty acids and Glycerol.
Question 5 How is the small intestine designed to absorb digested food? [CBSE 2024, 2020]
Answer: The small intestine is anatomically adapted for maximum nutrient absorption:
- Finger-like Projections (Villi): The inner mucosal lining contains millions of microscopic villi that increase the surface area for absorption by several hundred times.
- Rich Blood Capillary Network: Each villus is richly supplied with blood vessels and lymph vessels (lacteals) to rapidly transport absorbed nutrients to the liver and body cells.
- Thin Epithelial Walls: A single layer of epithelial cells allows rapid diffusion of glucose and amino acids into the bloodstream.
NCERT In-Text Questions: Set 3 (Page No. 91)
Question 1 What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration? [CBSE 2024, 2023]
Answer: Terrestrial organisms obtain oxygen directly from the atmospheric air, which contains about 21% oxygen.
In contrast, aquatic organisms must extract dissolved oxygen from water, which is present in very low concentrations (less than 1%). Therefore, aquatic animals (like fishes) must breathe much faster to meet their oxygen demands, whereas terrestrial animals can breathe at a normal, efficient rate with specialized lungs.
Question 2 What are the different ways in which glucose is oxidised to provide energy in various organisms? [CBSE 2024, 2022, 2020]
Answer: In all living organisms, glucose (a 6-carbon molecule) is first converted in the cytoplasm into Pyruvate (a 3-carbon molecule) via Glycolysis. Pyruvate is then broken down through three distinct pathways:
================================================================================
BIOCHEMICAL PATHWAYS OF GLUCOSE BREAKDOWN:
--------------------------------------------------------------------------------
Glucose (6-Carbon)
│
▼ (In Cytoplasm / Glycolysis)
Pyruvate (3-Carbon) + Energy
│
├── (1) In Yeast (Absence of O₂ / Fermentation):
│ Ethanol (C₂H₅OH) + CO₂ + Energy (2 ATP)
│
├── (2) In Muscle Cells (Lack of O₂ during heavy exercise):
│ Lactic Acid + Energy (2 ATP) [Causes Muscle Cramps]
│
└── (3) In Mitochondria (Presence of O₂ / Aerobic Respiration):
Carbon Dioxide (CO₂) + Water (H₂O) + Energy (36-38 ATP)
================================================================================
Question 3 How is oxygen and carbon dioxide transported in human beings? [CBSE 2024]
Answer:
- Oxygen Transport: Oxygen has low solubility in water, so 97% of it is transported bound to the iron-rich respiratory pigment Haemoglobin inside Red Blood Cells (RBCs) as Oxyhaemoglobin, while 3% dissolves in blood plasma.
- Carbon Dioxide Transport: Carbon dioxide is much more soluble in water than oxygen, so it is primarily transported in the dissolved form in blood plasma as Bicarbonate ions (HCO₃⁻) and carbaminohaemoglobin.
Question 4 How are the lungs designed in human beings to maximise the area for exchange of gases? [CBSE 2023, 2020]
Answer: Within the lungs, the respiratory passage branches into smaller tubes called bronchioles, which terminate into millions of balloon-like structures called Alveoli:
- Enormous Surface Area: The millions of alveoli provide an extensive surface area of nearly 80 square metres (equivalent to a tennis court).
- Thin Walls & Capillaries: The alveolar walls are extremely thin (one cell thick) and covered with an extensive network of blood capillaries for rapid gas exchange by diffusion.
NCERT In-Text Questions: Set 4 (Page No. 96)
Question 1 What are the components of the transport system in human beings? What are the functions of these components? [CBSE 2024]
Answer: The human circulatory system consists of three main components:
- The Heart: A muscular four-chambered pumping organ that pumps oxygenated blood to body tissues and sends deoxygenated blood to the lungs.
- Blood & Lymph (Circulatory Fluids):
- Blood: Transports oxygen, carbon dioxide, digested food, hormones, and urea.
- Lymph: Carries digested fats from the intestine and drains excess fluid back into the blood.
- Blood Vessels:
- Arteries: Carry oxygenated blood away from the heart at high pressure.
- Veins: Return deoxygenated blood back to the heart with one-way valves.
- Capillaries: Microscopic vessels where nutrient and gas exchange occurs with body cells.
Question 2 Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds? [CBSE 2024, 2020]
Answer: Mammals and birds are warm-blooded (endothermic) animals that constantly require large amounts of energy to maintain a constant body temperature regardless of environmental conditions.
Separating oxygenated and deoxygenated blood through a four-chambered heart prevents mixing, ensuring a highly efficient supply of oxygen to all tissues for cellular respiration.
Question 3 What are the components of the transport system in highly organised plants?
Answer: Highly organized vascular plants possess two complex conducting tissues:
- Xylem: Composed of Xylem Tracheids and Xylem Vessels that transport water and dissolved minerals upward from roots to leaves.
- Phloem: Composed of Sieve Tubes and Companion Cells that transport manufactured food (sucrose) and amino acids bidirectionally throughout the plant.
Question 4 How are water and minerals transported in plants? [CBSE 2023]
Answer: Water and minerals are transported through the xylem via two combined mechanisms:
- Root Pressure: Active intake of mineral ions by root cells creates an osmotic gradient, steadily pushing water upward into root xylem vessels.
- Transpiration Pull: Evaporation of water molecules from leaf stomata creates a continuous negative suction pressure (Transpiration Pull) that draws water columns upward from roots to the highest leaves.
Question 5 How is food transported in plants? [CBSE 2024]
Answer: The transport of soluble products of photosynthesis is called Translocation, which takes place in the Phloem sieve tubes:
- Sucrose is actively loaded into phloem tissue using energy from ATP.
- This increases osmotic pressure inside the sieve tubes, drawing water in and generating hydrostatic pressure.
- This pressure moves the food material to regions of lower pressure (such as growing shoots, storage roots, fruits, and seeds) in both upward and downward directions.
NCERT In-Text Questions: Set 5 (Page No. 98)
Question 1 Describe the structure and functioning of nephrons. [CBSE 2024, 2022]
Answer: A Nephron is the basic structural and functional filtration unit of the human kidney.
================================================================================
STRUCTURE AND FUNCTIONING OF A NEPHRON:
--------------------------------------------------------------------------------
1. Structure of Nephron:
• Bowman’s Capsule: A cup-shaped upper end housing a bundle of blood
capillaries called the Glomerulus.
• Renal Tubule: A long, coiled coiled tube (PCT, Loop of Henle, DCT) connected
to a collecting duct.
2. Mechanism of Urine Formation:
• Step 1: Ultrafiltration (In Glomerulus): High blood pressure forces water,
glucose, amino acids, salts, and urea through glomerulus walls into Bowman's capsule.
• Step 2: Selective Reabsorption (In Tubule): As filtrate flows through the tubule,
useful substances (all glucose, amino acids, essential salts, and major water)
are reabsorbed back into surrounding blood capillaries.
• Step 3: Tubular Secretion: Extra wastes and ions are secreted into the tubule,
leaving urine to enter the collecting duct.
================================================================================
Question 2 What are the methods used by plants to get rid of excretory products? [CBSE 2023, 2020]
Answer: Plants employ several strategies for waste disposal:
- Gaseous Wastes: Oxygen (by-product of photosynthesis) and Carbon Dioxide (from respiration) are released through Stomata and Lenticels.
- Excess Water: Eliminated through the process of Transpiration from leaf surfaces.
- Storage in Dead Parts: Many wastes are stored in cellular vacuoles of old leaves and bark that eventually fall off.
- Resins and Gums: Stored permanently in old, non-functional xylem tissue.
- Soil Excretion: Some waste substances are actively excreted into the soil around their roots.
Question 3 How is the amount of urine produced regulated? [CBSE 2024]
Answer: The volume of urine produced is regulated by two primary factors:
- Quantity of Excess Water in Body: If the body has excess water, less water is reabsorbed by kidney tubules, producing a larger volume of dilute urine. If dehydrated, maximum water is reabsorbed.
- Amount of Dissolved Wastes: A higher concentration of nitrogenous urea and salts requires more water to be excreted to eliminate the waste safely.
- Hormonal Control: The antidiuretic hormone (ADH / Vasopressin) controls the permeability of the collecting ducts for water reabsorption.
NCERT Chapter-End Exercises (Page No. 99-100)
Question 1 The kidneys in human beings are a part of the system for: (a) nutrition (b) respiration (c) excretion (d) transportation
Answer: (c) excretion Explanation: The kidneys filter nitrogenous metabolic waste products (urea, uric acid) from the blood to form urine.
Question 2 The xylem in plants are responsible for: (a) transport of water (b) transport of food (c) transport of amino acids (d) transport of oxygen
Answer: (a) transport of water Explanation: Xylem tissue conducts water and dissolved mineral salts unidirectionally from the roots to aerial plant parts.
Question 3 The autotrophic mode of nutrition requires: (a) carbon dioxide and water (b) chlorophyll (c) sunlight (d) all of the above
Answer: (d) all of the above Explanation: Photosynthesis requires carbon dioxide and water as chemical substrates, sunlight as the energy source, and chlorophyll to trap light energy.
Question 4 The breakdown of pyruvate to give carbon dioxide, water and energy takes place in: (a) cytoplasm (b) mitochondria (c) chloroplast (d) nucleus
Answer: (b) mitochondria Explanation: Aerobic respiration and the Krebs cycle occur inside the mitochondria, breaking down pyruvate completely into CO₂, H₂O, and 36–38 ATP.
Question 5 How are fats digested in our bodies? Where does this process take place? [CBSE 2024, 2022]
Answer: Fat digestion occurs primarily in the Small Intestine (Duodenum and Ileum):
- Emulsification by Bile Juice: Large, insoluble fat globules are broken down into small, microscopic droplets by Bile Salts secreted by the liver. This process is called Emulsification, which increases the surface area for enzyme action.
- Action of Pancreatic Lipase: Pancreatic juice contains the enzyme Lipase, which digests emulsified fat droplets into Fatty Acids and Glycerol.
- Intestinal Lipase: Enzymes in the intestinal juice complete the conversion of all fats into absorbable fatty acids and glycerol.
Question 6 What is the role of saliva in the digestion of food? [CBSE 2023, 2020]
Answer: Saliva secreted by the salivary glands plays three critical roles:
- Enzymatic Digestion of Starch: It contains the digestive enzyme Salivary Amylase (Ptyalin), which hydrolyzes complex starch into simpler maltose sugar:
Starch + Salivary Amylase (pH 6.8) → Maltose Sugar - Lubrication of Food: Mucus in saliva moistens, softens, and lubricates dry food particles into a smooth mass called a Bolus for easy swallowing.
- Oral Hygiene: It contains lysozyme that kills harmful oral bacteria.
Question 7 What are the necessary conditions for autotrophic nutrition and what are its by-products? [CBSE 2024]
Answer:
- Necessary Conditions:
- Availability of Carbon Dioxide (CO₂).
- Absorption of Water (H₂O) by roots.
- Presence of Chlorophyll pigment in chloroplasts.
- Availability of Sunlight / Solar energy.
- Balanced Equation:
6CO₂ + 12H₂O —(Sunlight / Chlorophyll)→ C₆H₁₂O₆ (Glucose) + 6O₂↑ + 6H₂O - By-Products: Oxygen gas (O₂) and Water vapor (H₂O) are the by-products released into the atmosphere.
Question 8 What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration. [CBSE 2024, 2020]
Answer:
| Parameter | Aerobic Respiration | Anaerobic Respiration |
|---|---|---|
| Oxygen Requirement | Occurs strictly in the presence of Oxygen (O₂). | Occurs in the absence of Oxygen (O₂). |
| Site of Reaction | Occurs in Cytoplasm and Mitochondria. | Occurs strictly in the Cytoplasm only. |
| End Products | Carbon Dioxide (CO₂) and Water (H₂O). | Ethanol + CO₂ (in yeast) or Lactic Acid (in muscles). |
| Energy Output | High energy yield (36 to 38 ATP per glucose). | Low energy yield (Only 2 ATP per glucose). |
| Complete Breakdown | Complete oxidation of glucose takes place. | Incomplete breakdown of glucose occurs. |
- Organisms using Anaerobic Respiration: Yeast, anaerobic bacteria, parasitic endoparasites (tapeworms, roundworms).
Question 9 How are the alveoli designed to maximise the exchange of gases? [CBSE 2023]
Answer: Alveoli are specialized for gas exchange through the following structural adaptations:
- Massive Surface Area: Nearly 300 to 400 million alveoli in human lungs provide a surface area of over 80 m².
- Extremely Thin Membrane: The alveolar wall consists of a single layer of squamous epithelial cells, minimizing the diffusion distance for gases.
- Extensive Capillary Network: Surrounded by dense blood capillary networks, facilitating the diffusion of oxygen into RBCs and carbon dioxide into the alveolar air.
Question 10 What would be the consequences of a deficiency of haemoglobin in our bodies? [CBSE 2024, 2020]
Answer: A deficiency of haemoglobin leads to a clinical condition called Anaemia:
- Reduced Oxygen-Carrying Capacity: The blood cannot transport sufficient oxygen to body tissues and brain cells.
- Impaired Cellular Respiration: Slower cellular respiration reduces the rate of ATP energy generation.
- Symptoms: The person suffers from chronic fatigue, breathlessness, dizziness, pale skin, weakness, and poor cognitive concentration.
Question 11 Describe double circulation in human beings. Why is it necessary? [CBSE 2024, 2022]
Answer: In double circulation, blood passes through the human heart twice during one complete cardiac cycle:
================================================================================ THE TWO PATHWAYS OF DOUBLE CIRCULATION: -------------------------------------------------------------------------------- 1. Pulmonary Circulation: Deoxygenated blood (Right Ventricle) → Pulmonary Artery → Lungs (Oxygenation) → Pulmonary Veins → Left Atrium (Heart). 2. Systemic Circulation: Oxygenated blood (Left Ventricle) → Aorta → Body Tissues & Organs → Vena Cava (Deoxygenated) → Right Atrium (Heart). ================================================================================
Why it is Necessary: Double circulation completely separates oxygenated blood from deoxygenated blood. This ensures an efficient supply of high-pressure oxygenated blood required by warm-blooded mammals to maintain a constant internal body temperature.
Question 12 What are the differences between the transport of materials in xylem and phloem? [CBSE 2023, 2020]
Answer:
| Parameter | Transport in Xylem | Transport in Phloem |
|---|---|---|
| Substance Transported | Water and dissolved mineral salts. | Soluble organic food (Sucrose) and amino acids. |
| Direction | Unidirectional (Upward from roots to leaves). | Bidirectional (Upward and downward to storage and growing organs). |
| Mechanism / Energy | Driven by physical forces (Transpiration pull); no metabolic ATP energy required. | Driven by active transport using cellular ATP energy and osmotic pressure. |
| Tissue Components | Tracheids, vessels, xylem parenchyma, and fibers. | Sieve tubes, companion cells, phloem parenchyma, and fibers. |
Question 13 Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning. [CBSE 2024, 2020]
Answer:
| Parameter | Alveoli (Lungs) | Nephrons (Kidneys) |
|---|---|---|
| Basic Function | Functional units of Respiration and Gas Exchange. | Functional units of Excretion and Osmoregulation. |
| Structure | Tiny, thin-walled, balloon-like air sacs surrounded by blood capillaries. | Long, tubular structures composed of a Bowman’s capsule, glomerulus, and coiled renal tubules. |
| Filtration vs Diffusion | Gaseous exchange occurs across membranes by simple physical diffusion. | Liquid waste is filtered under pressure by Ultrafiltration and Selective Reabsorption. |
| Substances Exchanged / Removed | Takes in Oxygen (O₂) and expels Carbon Dioxide (CO₂). | Removes nitrogenous urea, uric acid, and excess salts to form liquid urine. |
Frequently Asked Questions (FAQs) – Class 10 Biology Chapter 5
Question 1: What is peristalsis? [CBSE 2024] Answer: Peristalsis is the rhythmic, wave-like contraction and relaxation of the muscular walls of the alimentary canal (especially the oesophagus) that pushes food downward through the digestive tract.
Question 2: What is the dental formula of an adult human and what causes dental caries? [CBSE 2023] Answer: The adult dental formula is 2123/2123. Dental caries (tooth decay) is caused by oral bacteria fermenting trapped dietary sugars into acids that dissolve the protective calcium hydroxyapatite enamel.
Question 3: Why are the walls of ventricles thicker than atria? [CBSE 2024] Answer: Ventricles must pump blood with high pressure to distant organs and lungs, whereas atria only receive blood and push it into the adjacent ventricles.
Question 4: What is the normal blood pressure of a healthy adult human? [CBSE 2023] Answer: The normal blood pressure is 120/80 mm Hg (Systolic pressure = 120 mm Hg, Diastolic pressure = 80 mm Hg), measured using a sphygmomanometer.
Question 5: What is the function of blood platelets? [CBSE 2022] Answer: Platelets circulate in the blood and form clots at points of injury by forming a mesh of fibrin threads, preventing excessive blood loss and maintaining vascular pressure.
Question 6: What is lymph and how does it differ from blood? [CBSE 2024] Answer: Lymph is a clear, straw-colored tissue fluid that filters into intercellular spaces. Unlike blood, lymph lacks RBCs and large proteins, contains fewer nutrients, but is rich in lymphocytes that fight infection.
Question 7: What is the role of bile juice in digestion? [CBSE 2024] Answer: Bile juice (secreted by the liver) contains no enzymes, but its alkaline bile salts neutralize acidic chyme from the stomach and emulsify large fat globules into small droplets for lipase action.
Question 8: Why do desert plants open their stomata at night? [CBSE 2023] Answer: To prevent excessive water loss through transpiration during hot days, desert plants take in CO₂ at night, store it as an intermediate organic acid, and use sunlight during the day to complete photosynthesis.
Question 9: What is the compensation point in plants? [BOARD EXAM FAVORITE] Answer: It is the light intensity (usually at dawn and dusk) at which the rate of photosynthesis equals the rate of respiration, resulting in zero net exchange of CO₂ and O₂ with the atmosphere.
Question 10: What is dialysis (artificial kidney)? [CBSE 2024] Answer: Dialysis is a medical procedure used to remove nitrogenous metabolic waste products (like urea) from the blood of patients suffering from kidney failure using a semi-permeable dialysing machine.
Question 11: What is the role of the epiglottis? [CBSE 2022] Answer: The epiglottis is a flap of cartilage behind the tongue that covers the windpipe (trachea) during swallowing, preventing food particles from entering the respiratory tract.
Question 12: Why is the small intestine in herbivores longer than in carnivores? [CBSE 2024, 2020] Answer: Herbivores eat cellulose-rich plant matter, which takes a longer time and specialized bacteria to digest. Carnivores eat meat, which is easier to digest, so their small intestine is comparatively shorter.
Question 13: What prevents the collapse of the trachea during breathing? [CBSE 2023] Answer: C-shaped rings of cartilage present in the tracheal wall provide structural support and prevent the trachea from collapsing when there is less air in it.
Question 14: What is translocation in plants? [CBSE 2024] Answer: Translocation is the active transport of soluble products of photosynthesis (sucrose, amino acids) from leaves to other storage and growing organs through phloem sieve tubes using ATP energy.
Question 15: What is the functional difference between an artery and a vein? [CBSE 2024] Answer: Arteries have thick, elastic walls without valves and carry oxygenated blood away from the heart at high pressure; veins have thinner walls with one-way valves to prevent backflow as they return deoxygenated blood to the heart.
Mastering the NCERT Solutions for Class 10 Science Chapter 5, “Life Processes”, provides students with the physiological mechanisms, biochemical equations, and anatomical comparisons required for the CBSE Board Examination. Review the pathways of glucose oxidation, the double circulation schematic, and the 15 board-level FAQs above to secure full marks in your biology evaluations.