Brain Grain · braingrain.in
Science — Practice Paper · Set 1
Class: 9Samacheer KalviMax Marks: 79
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 3 × 1 = 3
Choose the correct answer. (Answer all questions.)
1.Which one of the following is most likely not a case of uniform circular motion?[1]
2.Which of the following converts electrical energy into mechanical energy?[1]
3.Choose the correct one.[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
4.______ compounds generally have high melting and boiling points.[1]
5.In petroleum refining, the method of separation used is ______.[1]
6.Buckminster Fullerene contains ______ carbon atoms.[1]
7.Alcohol can be separated from water by ______.[1]
8.______ named carbon.[1]
Part III — Short Answer Questions 18 × 2 = 36
Answer briefly. (Answer all questions.)
9.Skin of reptiles is smooth and moist.[2]
10.What is a Presentation?[2]
11.Identify Compound Type[2]
12.Final Temperature of Water Mixture[2]
13.Which key is used to run a slide show?[2]
14.Differentiate Flatworms and Roundworms[2]
15.Technical Terms[2]
16.What is Catenation?[2]
17.Classification of Cattle Breeds[2]
18.Antibiotic penicillin is obtained from[2]
19.Food Additives and Their Functions[2]
20.What are electric lines of force?[2]
21.Mars is called the Red Planet.[2]
22.Five Features of Fishes[2]
23.Define Allotropy[2]
24.Can Watch Batteries be Recharged?[2]
25.Change in number of neutrons changes an atom into[2]
26.Ways to Save Water[2]
Part IV — Long Answer Questions 7 × 5 = 35
Answer in detail. (Answer all questions.)
27.Resistance from V-I Graph[5]
28.Write About Orbital Velocity[5]
29.Permanent Tissues and Simple Permanent Tissues[5]
30.Human Activities Affecting Nitrogen Cycle[5]
31.Structure of Kidney and Urine Formation[5]
32.Explain Two Types of Transformers[5]
33.Types of Dyes Based on Application[5]
🔑 Show Answer Key — Set 1
- 1. (a) Motion of the Earth around the Sun (b) Motion of a toy train on a circular track (c) Motion of a racing car on a circular track (d) Motion of the hour hand on a clock dial Answer: (c) Motion of a racing car on a circular track
- 2. (a) Motor (b) Battery (c) Generator (d) Switch Answer: (a) Motor
- 3. (a) mm < cm < m < km (b) mm > cm > m > km (c) km < m < cm < mm (d) mm > m > cm > km Answer: (a) mm < cm < m < km
- 4. (a) Covalent (b) Coordinate (c) Ionic Answer: (c) Ionic
- 5. fractional distillation
- 6. 60
- 7. fractional distillation
- 8. Antoine Lavoisier
- 9. False. Correct Statement: The skin of amphibians is smooth and moist, not reptiles. Amphibians such as frogs, toads, and salamanders have smooth, permeable skin that must remain moist to facilitate cutaneous respiration and prevent desiccation. In contrast, reptiles have dry, scaly skin covered with keratin that provides protection against water loss and is adapted for life primarily on land. This fundamental difference in skin structure reflects the different habitats and physiological requirements of these two vertebrate classes.
- 10. A presentation is a structured method of delivering information systematically using: text pictures charts audio video animations
- 11. Characteristic Compound Type Soluble in non-polar solvent Covalent Fast reactions in aqueous solution Ionic Non-conductor Covalent Crystalline solid at room temperature Ionic
- 12. Given: $$m_1 = 100g$$ $$T_1 = 90^\circ C$$ $$m_2 = 600g$$ $$T_2 = 20^\circ C$$ Using heat balance: $$m_1(T_1-T_f)=m_2(T_f-T_2)$$ $$100(90-T_f)=600(T_f-20)$$ Solving: $$T_f = 30^\circ C$$
- 13. (a) F1 (b) Tab (c) F5 (d) F2 Answer: (c) F5
- 14. Flatworms Roundworms Phylum Platyhelminthes Phylum Aschelminthes Acoelomate Pseudocoelomate Mostly hermaphrodite Sexes separate Flat body Cylindrical body Simple alimentary canal Complete alimentary canal Example: Tapeworm Example: Ascaris
- 15. (a) Growth-dependent movement is called tropic movement. Tropic movements are directional responses to stimuli where the direction of movement is determined by the direction of the stimulus. These movements involve cell elongation and are permanent. Examples include phototropism and geotropism. (b) Growth-independent movement is called nastic movement. Nastic movements are non-directional responses to stimuli where the direction of movement is independent of the stimulus direction. These movements occur due to changes in turgor pressure and are reversible. Examples include photonasty and thigmonasty. <div
- 16. Catenation is property by which atoms of same element link together through covalent bonds. Carbon and Catenation Carbon atoms bond with one another repeatedly. They form: straight chains branched chains ring structures This leads to enormous number of organic compounds. Examples: Starch Cellulose Hydrocarbons
- 17. Type Examples Milch breeds Sahiwal, Gir Draught breeds Kangayam, Hallikar Dual-purpose breeds Hariana, Ongole
- 18. (a) plant (b) microorganism (c) animal (d) sunlight Answer: (b) microorganism
- 19. Food Additive Function Preservatives Prevent spoilage Colouring agents Improve appearance Flavouring agents Improve taste Sweeteners Add sweetness Antioxidants Prevent oxidation Emulsifiers Stabilize mixtures
- 20. Electric lines of force are imaginary lines drawn in space around a charged body that represent the direction and strength of the electric field at any point. These lines originate from positive charges and terminate at negative charges. The direction of an electric line of force at any point is the same as the direction of the electric force that would act on a small positive test charge placed at that point. The density of these lines indicates the strength of the electric field in that region. Regions with closely spaced lines have a stronger electric field, while regions with widely spaced lines have a weaker field. Electric lines of force never intersect each other because at any poi…
- 21. This statement is true. Mars is called the Red Planet because its surface appears reddish in color. This reddish appearance is due to the presence of iron oxide, commonly known as rust, on the Martian surface. The iron oxide gives Mars its distinctive red hue, which is visible even from Earth when observed through telescopes. This characteristic color is one of the most recognizable features of Mars and is the reason it has earned the nickname the Red Planet.
- 22. Aquatic vertebrates Cold-blooded Body streamlined Respiration by gills Locomotion by fins Heart is two-chambered Types of Fishes Cartilaginous fishes Example: Shark Skate Bony fishes Example: Carp Mullet
- 23. Property by which an element exists in more than one form in same physical state is called allotropy. Examples: Diamond Graphite Fullerene <div
- 24. No, watch batteries cannot be recharged. Watch batteries are typically primary cells, which means they contain chemical reactions that are irreversible. Once the chemical reactants in a primary cell are consumed, the battery cannot be restored to its original state by applying an external electric current, and therefore cannot be recharged. In contrast, mobile phone batteries use secondary cells, specifically lithium-ion batteries, which contain reversible chemical reactions. The reversible nature of the chemical reactions in secondary cells allows them to be recharged multiple times by applying an external electric current, which reverses the chemical reaction and restores the battery's…
- 25. (a) ion (b) isotope (c) isobar (d) another element Answer: (b) isotope
- 26. Repair leaking taps Use low-flow taps Reuse water Use recycled water for gardens
- 27. Using Ohm’s law: $$R = \frac{V_2 - V_1}{I_2 - I_1}$$ $$R = \frac{13.2 - 10.2}{4 - 3}$$ $$R = \frac{3}{1}$$ $$R = 3\Omega$$ 8 Intext Activities 0 questions 9 Activity – 1 0 questions Electrical Symbols in Electronic Circuits Aim: To identify electrical symbols used in electronic devices. Observation: Common symbols observed include: Cell Battery Switch Resistor Capacitor LED 10 Activity – 2 0 questions Heating Effect of Electric Current Aim: To observe heating effect of electric current. Observation: The pointed aluminium foil melts when current passes through it. Conclusion: Electrical energy converts into heat energy due to resistance. This is called: Joule Heating 11 Activity – 3 0 ques…
- 28. Definition Minimum horizontal velocity needed to keep satellite in orbit. Important Points Depends on altitude Nearer satellites require greater speed Formula $$v = \sqrt{\frac{GM}{R+h}}$$ Where: (G) = gravitational constant (M) = mass of Earth (R) = radius of Earth (h) = orbital height Geostationary Orbit Satellite appears fixed relative to Earth. Orbital period: $$24 \text{ hours}$$
- 29. # Permanent Tissue Tissues whose cells have lost power of division are called permanent tissues. # Types of Simple Permanent Tissues # (i) Parenchyma Features Living cells Thin-walled Polygonal or oval Intercellular spaces present Special Types Aerenchyma Contains air spaces. Found in aquatic plants. Chlorenchyma Contains chloroplasts. Performs photosynthesis. Functions Food storage Photosynthesis Buoyancy Secretion # (ii) Collenchyma Features Living elongated cells Unevenly thickened corners Non-lignified walls Function Provides flexibility and mechanical support. # (iii) Sclerenchyma Features Dead cells Thick lignified walls Mechanical strength Types Fibres Long pointed cells Example: J…
- 30. Human activities that disturb the nitrogen cycle include: Excessive use of nitrogenous fertilizers and manure, causing nitrate runoff and eutrophication. Industrial nitrogen fixation, which increases reactive nitrogen in ecosystems. Burning fossil fuels, which releases nitrogen oxides and causes smog and acid rain. Deforestation and land-use change, which alter nitrogen inputs and losses. Discharge of nitrogen-rich wastewater into water bodies.
- 31. # Structure of Kidney Bean-shaped organs Located on either side of vertebral column Right kidney slightly lower Internal Structure Cortex Outer region Medulla Inner region Contains renal pyramids. Hilum Entry point for: blood vessels nerves ureter # Steps in Urine Formation # (i) Glomerular Filtration Blood filtered in glomerulus. Filtrate enters Bowman’s capsule. # (ii) Tubular Reabsorption Useful substances reabsorbed: glucose amino acids water salts # (iii) Tubular Secretion Waste ions secreted into tubule. Final urine formed. # Path of Urine $$Kidney \rightarrow Ureter \rightarrow Urinary\ bladder \rightarrow Urethra$$
- 32. # Step-Up Transformer Principle: A transformer works on mutual induction. Alternating current in the primary coil produces changing magnetic flux in the iron core, inducing emf in the secondary coil. Converts low voltage AC into high voltage AC Secondary coil has more turns $$N_s > N_p$$ $$V_s > V_p$$ # Step-Down Transformer Converts high voltage AC into low voltage AC Secondary coil has fewer turns $$N_s < N_p$$ $$V_s < V_p$$ For an ideal transformer: $$\frac{V_s}{V_p}=\frac{N_s}{N_p}$$
- 33. # (i) Acid Dyes Acidic in nature Used for wool and silk Examples: Picric acid Naphthol yellow-S # (ii) Basic Dyes Contain basic groups like: $$-NH_2,\ -NHR,\ -NR_2$$ Examples: Crystal violet Methylene blue # (iii) Mordant Dyes Require mordant before dyeing. Mordants: Aluminium salts Chromium salts Iron salts Example: Alizarin # (iv) Direct Dyes Used directly on cotton and rayon. Example: Congo red # (v) Vat Dyes Used mainly for cotton. Example: Indigo
Brain Grain · braingrain.in
Science — Practice Paper · Set 2
Class: 9Samacheer KalviMax Marks: 79
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 3 × 1 = 3
Choose the correct answer. (Answer all questions.)
1.Which one of the following is most likely not a case of uniform circular motion?[1]
2.Which of the following converts electrical energy into mechanical energy?[1]
3.Choose the correct one.[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
4.______ has same properties throughout the sample.[1]
5.There are ______ plastic resin codes.[1]
6.A ______ mixture has no visible boundary between components.[1]
7.______ is an electrochemical cell which converts electrical energy into chemical change (reaction).[1]
8.Number of neutrons in (,^{7}_{3}Li) is ______.[1]
Part III — Short Answer Questions 18 × 2 = 36
Answer briefly. (Answer all questions.)
9.Which nutrient protects from deficiency diseases?[2]
10.A physical balance is more sensitive than a beam balance.[2]
11.Ice Cube in Water and Alcohol[2]
12.Stomach mainly digests[2]
13.Milch animals are used in agriculture and transport.[2]
14.Smaller orbit size means lower energy.[2]
15.Orbital Velocity of Satellite[2]
16.Why do people wear white clothes in summer?[2]
17.Conclusions from Rutherford’s Gold Foil Experiment[2]
18.Need for Chemical Fertilizers[2]
19.Companion cells are closely associated with[2]
20.Electronic Configuration of K and Cl[2]
21.What Happens if Blood Platelets are Removed?[2]
22.Factors of biosphere affecting survival and reproduction are called[2]
23.Why is Ocean Blue?[2]
24.Metal carbonates and bicarbonates react with acids to liberate[2]
25.Structural and functional unit of kidney is[2]
26.Rubbing a comb with hair[2]
Part IV — Long Answer Questions 7 × 5 = 35
Answer in detail. (Answer all questions.)
27.Significance of Hexagonal Honeycomb Cells[5]
28.Explain Principle, Construction and Working of a DC Motor[5]
29.Account of All Planets[5]
30.Which Blood Cells are Not True Cells?[5]
31.If the velocity-time graph of a particle is a straight line inclined to the x-axis, then its displacement-time graph will also be a straight line.[5]
32.An airtight plastic bottle pushed into water experiences increasing force at the bottom because[5]
33.Correct Incorrect Statements[5]
🔑 Show Answer Key — Set 2
- 1. (a) Motion of the Earth around the Sun (b) Motion of a toy train on a circular track (c) Motion of a racing car on a circular track (d) Motion of the hour hand on a clock dial Answer: (c) Motion of a racing car on a circular track
- 2. (a) Motor (b) Battery (c) Generator (d) Switch Answer: (a) Motor
- 3. (a) mm < cm < m < km (b) mm > cm > m > km (c) km < m < cm < mm (d) mm > m > cm > km Answer: (a) mm < cm < m < km
- 4. (a) Pure substance (b) Mixture (c) Colloid (d) Suspension Answer: (a) Pure substance
- 5. seven
- 6. homogeneous
- 7. Electrolytic cell
- 8. 4
- 9. (a) Carbohydrates (b) Vitamins (c) Proteins (d) Fats Answer: (b) Vitamins
- 10. True. A physical balance is more sensitive than a beam balance. A physical balance can detect smaller differences in mass and provides greater precision in measurements. This is because a physical balance has a more delicate construction and can measure mass to a higher degree of accuracy compared to a beam balance, which is a simpler instrument. The physical balance is therefore preferred in laboratories when precise measurements are required.
- 11. Observation: Liquid Result Water Ice floats Alcohol Ice sinks Reason: $$\rho_{ice} = 0.917$$ $$\rho_{water} = 1.0$$ $$\rho_{alcohol} = 0.78$$
- 12. (a) carbohydrates (b) proteins (c) fats (d) sucrose Answer: (b) proteins
- 13. False. Correct Statement: Milch animals are primarily reared for milk production, not for agriculture and transport. Milch animals such as cows, buffalo, and goats are dairy animals specifically bred and maintained to produce milk and milk products like yogurt, cheese, and butter. While some milch animals may occasionally be used for other purposes, their main economic value and purpose is milk production.
- 14. This statement is true. According to Bohr's model of the atom, electrons in smaller orbits closer to the nucleus have lower energy levels compared to electrons in larger orbits farther from the nucleus. The energy of an electron is inversely related to the size of its orbit. Electrons in the first orbit (n=1) have the lowest energy, those in the second orbit (n=2) have higher energy, and so on. This is why electrons naturally occupy the lowest available energy levels, filling inner orbits before moving to outer orbits.
- 15. Given: $$h = 36000km$$ $$R = 6370km$$ Using orbital velocity formula: $$v = \sqrt{\frac{GM}{R+h}}$$ Answer: $$v = 3.067 \times 10^3 m/s$$ or $$3.067km/s$$
- 16. People wear white clothes in summer because white color reflects most of the heat radiation falling on it and absorbs very little heat. When sunlight falls on white fabric, a large portion of the radiation is reflected back into the surroundings rather than being absorbed by the cloth. This means less heat is transferred to the body, helping to keep the person cool and comfortable. In contrast, dark colors absorb most of the heat radiation, which increases the temperature of the cloth and makes the body feel hotter. Therefore, white clothes are more suitable for summer wear as they minimize heat absorption and help maintain a lower body temperature.
- 17. Conclusions Atom contains very small nucleus. Most of atom is empty space. Entire positive charge concentrated in nucleus. Most mass concentrated in nucleus. Electrons revolve around nucleus.
- 18. Chemical fertilizers supply essential nutrients required for healthy plant growth. Macronutrients: Nitrogen Phosphorus Potassium
- 19. (a) Sieve elements (b) Vessel elements (c) Trichomes (d) Guard cells Answer: (a) Sieve elements <div
- 20. Potassium (K) Atomic number = 19 $$2,8,8,1$$ Chlorine (Cl) Atomic number = 17 $$2,8,7$$
- 21. Platelets help blood clotting. Without platelets: clotting will not occur excessive bleeding occurs may become fatal
- 22. (a) Biological factors (b) Abiotic factors (c) Biotic factors (d) Physical factors Answer: (c) Biotic factors
- 23. Water absorbs longer wavelengths of light such as red and orange more strongly than shorter wavelengths. The shorter wavelengths, particularly blue light, are scattered more effectively by water molecules. When sunlight enters the ocean, the longer wavelengths are absorbed within the upper layers and converted to heat, while the blue wavelengths are scattered back towards our eyes. This scattered blue light is what we perceive when looking at the ocean, making it appear blue. The depth of water also plays a role, as deeper oceans appear darker blue because more light is absorbed before reaching greater depths.
- 24. (NO_2) (SO_2) (CO_2) Answer: $$CO_2$$
- 25. (a) villi (b) liver (c) nephron (d) ureter Answer: (c) nephron <div
- 26. (a) creates electric charge (b) transfers electric charge (c) either (a) or (b) (d) neither (a) nor (b) Answer: (b) transfers electric charge Charges are not created; electrons are transferred.
- 27. Honeycomb is made from wax secreted by worker bees. Importance of Hexagonal Shape Maximum storage with minimum wax Strong structure Stores honey and pollen Used for rearing larvae
- 28. # Principle A current-carrying conductor placed in magnetic field experiences force. Direction is determined using Fleming’s Left Hand Rule. # Construction Main parts: Armature coil Field magnet Split ring commutator Carbon brushes Battery # Working Current passes through armature coil. Opposite sides of coil experience opposite forces. Coil rotates. Split ring reverses current every half rotation. Continuous rotation is produced. Thus electrical energy converts into mechanical energy.
- 29. # Mercury Nearest planet to Sun Rocky planet Fastest revolution # Venus Hottest planet Similar size to Earth Rotates opposite direction # Earth Only known life-supporting planet Blue appearance due to water Revolution period: $$365.25 \text{ days}$$ # Mars Red planet Two small moons # Jupiter Largest planet Gas giant Has Great Red Spot # Saturn Famous for rings Gas giant # Uranus Rotates on its side Cold gas giant # Neptune Windiest planet Has moon Triton
- 30. Mature red blood cells are not true cells because they lack nucleus. Correction made: RBCs possess nucleus only during immature stage.
- 31. False Correct Statement: If the velocity-time graph is a straight inclined line, the displacement-time graph will be a curve because the body is uniformly accelerated. Correction made: Original answer marked as True was incorrect.
- 32. (a) more liquid is displaced (b) more weight of liquid is displaced (c) pressure increases with depth (d) All the above Answer: (c) pressure increases with depth
- 33. (a) Simple molecular species containing coordinate covalent bonds are generally non-ionic and poor conductors. Coordination compounds that form ionic salts may contain complex ions and can conduct electricity in aqueous solution. (b) Ionic bond is stronger than hydrogen bond. (c) Covalent bonds form by sharing of electrons between atoms. In a coordinate covalent bond, the shared pair comes from one atom. (d) Correct statement. Loss of electrons → oxidation Gain of electrons → reduction (e) Electrons not involved in bonding are called: Lone pair (non-bonding) electrons
Brain Grain · braingrain.in
Science — Practice Paper · Set 3
Class: 9Samacheer KalviMax Marks: 79
Name: ____________________Reg No: ____________
Part I — Multiple Choice Questions 3 × 1 = 3
Choose the correct answer. (Answer all questions.)
1.Which one of the following is most likely not a case of uniform circular motion?[1]
2.Which of the following converts electrical energy into mechanical energy?[1]
3.Choose the correct one.[1]
Part II — Fill in the Blanks 5 × 1 = 5
Fill in the blanks. (Answer all questions.)
4.Legal measures to prevent plastic pollution come under the ______ Protection Act.[1]
5.Electric field lines ______ from positive charge and ______ in negative charge.[1]
6.Fill in the Blanks __________[1]
7.______ isotope is used in the nuclear reactors.[1]
8.Noble gases belong to ______.[1]
Part III — Short Answer Questions 18 × 2 = 36
Answer briefly. (Answer all questions.)
9.In an electrolyte, current is due to flow of[2]
10.Adaptations of Bats[2]
11.Question 1[2]
12.Define Sublimation[2]
13.Separation of denser particles from lighter particles by high-speed rotation is called[2]
14.Vitamins are required in large quantities.[2]
15.Epithelial tissue is protective tissue in animals.[2]
16.Applications of Ultrasonic Sound[2]
17.Uses of Aqua Regia[2]
18.Bone and cartilage are areolar connective tissues.[2]
19.Dioxins and PVC Plastics[2]
20.Age of dead organisms can be determined using isotope of[2]
21.Differentiate Step-Up and Step-Down Transformer[2]
22.Nitric acid in stomach kills microorganisms.[2]
23.List Main Parts of an Electric Motor[2]
24.Locomotion in Starfish[2]
25.Italian species of honey bee is[2]
26.What are Nucleons?[2]
Part IV — Long Answer Questions 7 × 5 = 35
Answer in detail. (Answer all questions.)
27.What are Intercalary Meristems?[5]
28.Limitations of Mendeleev’s Periodic Table[5]
29.Big Bang occurred approximately[5]
30.Bird Limb Adaptations[5]
31.Account of Phylum Arthropoda[5]
32.Fertilizer for Soil with pH 5[5]
33.Chlorinated hydrocarbons are used as[5]
🔑 Show Answer Key — Set 3
- 1. (a) Motion of the Earth around the Sun (b) Motion of a toy train on a circular track (c) Motion of a racing car on a circular track (d) Motion of the hour hand on a clock dial Answer: (c) Motion of a racing car on a circular track
- 2. (a) Motor (b) Battery (c) Generator (d) Switch Answer: (a) Motor
- 3. (a) mm < cm < m < km (b) mm > cm > m > km (c) km < m < cm < mm (d) mm > m > cm > km Answer: (a) mm < cm < m < km
- 4. (a) Forest (b) Wildlife (c) Environment (d) Human rights Answer: (c) Environment
- 5. (a) start; start (b) start; end (c) start; end (d) end; end Answer: (b) start; end
- 6. Stimulus Response Light Phototropism Gravity Geotropism Water Hydrotropism Touch Thigmotropism
- 7. Uranium-235
- 8. Group 18
- 9. (a) electrons (b) positive ions only (c) both positive and negative ions (d) neither (a) nor (b) Answer: (c) both positive and negative ions Current in an electrolyte is due to movement of ions. Electrons do not carry current through the bulk of the electrolyte.
- 10. Live in caves Nocturnal habit Use echolocation Undergo hibernation Wings adapted for flight
- 11. Assertion: Urea is excreted through kidneys. Reason: Urea is toxic. Answer: (a) Both are true and reason correctly explains assertion. Urea is a nitrogenous waste product formed during protein metabolism in the liver. It is toxic to the body and must be removed to prevent harmful accumulation. The kidneys filter urea from the blood and excrete it in urine, making them the primary organs responsible for urea elimination. This process is essential for maintaining the body's internal environment and preventing the toxic effects of nitrogenous waste.
- 12. Direct conversion of solid into vapour without becoming liquid is called sublimation. Examples: Camphor Naphthalene Dry ice
- 13. (a) Filtration (b) Sedimentation (c) Decantation (d) Centrifugation Answer: (d) Centrifugation
- 14. False. Correct Statement: Vitamins are required in minute quantities. Although vitamins are essential nutrients necessary for various metabolic processes, growth, and disease prevention, they are needed only in very small amounts compared to macronutrients like carbohydrates, proteins, and fats. The body cannot synthesize most vitamins and must obtain them from food sources. Even though required in minute quantities, deficiency of any vitamin can lead to serious health problems and deficiency diseases. Therefore, the statement that vitamins are required in large quantities is incorrect.
- 15. True. Epithelial tissue is indeed a protective tissue in animals. It forms the outer covering of the body and lines the internal organs and cavities. The epithelial tissue acts as a barrier against mechanical injury, pathogens, and water loss. Different types of epithelial tissues, such as stratified squamous epithelium in the skin and simple columnar epithelium in the digestive tract, are specifically adapted to provide protection in their respective locations while also performing other functions like absorption and secretion.
- 16. Cleaning Used to remove tiny dust particles from delicate objects. Industry Used to detect cracks in metal blocks. Medicine (i) Echocardiography Ultrasound used to study heart. (ii) Kidney Stones Ultrasonic waves break stones into smaller pieces.
- 17. Aqua Regia Mixture of: $$HCl : HNO_3 = 3 : 1$$ Uses Dissolves gold and platinum Cleaning and refining gold
- 18. False. Bone and cartilage are not areolar connective tissues. They are supportive connective tissues. Areolar connective tissue is a loose connective tissue found beneath the skin and between organs, containing fibroblasts, collagen fibers, and elastic fibers in a gel-like matrix. In contrast, bone is a rigid connective tissue with a mineralized matrix containing calcium and phosphate, while cartilage is a firm but flexible connective tissue with a matrix of collagen fibers and proteoglycans. Both bone and cartilage provide structural support and protection to the body.
- 19. # Formation of Dioxins Dioxins form during: burning plastics industrial processes waste incineration Especially when chlorine-containing materials burn. # Linked Plastic PVC (Polyvinyl Chloride) # Harmful Effects Cancer Hormonal imbalance Immune suppression Reproductive disorders Developmental defects
- 20. (a) carbon (b) iodine (c) phosphorus (d) oxygen Answer: (a) carbon Carbon-14 isotope is used.
- 21. Step-Up Transformer Step-Down Transformer Increases voltage Decreases voltage (V_s > V_p) (V_s < V_p) (N_s > N_p) (N_s < N_p) Current decreases Current increases Used in power stations Used in chargers Where: (N_s) = turns in secondary coil (N_p) = turns in primary coil
- 22. False. Correct Statement: Hydrochloric acid in the stomach kills microorganisms. Hydrochloric acid is secreted by the parietal cells of the gastric glands in the stomach and creates an acidic environment with a pH of about 1.5 to 3.5. This highly acidic medium is lethal to most microorganisms that may enter the stomach with food, providing a protective function against bacterial and other microbial infections. Nitric acid is not present in the stomach.
- 23. Field magnet Armature coil Split ring commutator Carbon brushes Battery
- 24. Locomotion in starfish occurs through the coordinated action of tube feet, which are small, sucker-like structures distributed across the arms and body surface. These tube feet are part of the water vascular system, a unique hydraulic system found only in echinoderms. The water vascular system contains fluid-filled canals that connect to each tube foot, allowing them to extend and contract. When the tube feet extend and attach to the substrate using their suckers, they pull the starfish forward in a slow, gliding motion. This mechanism enables starfish to move across the ocean floor and climb vertical surfaces with remarkable efficiency.
- 25. (a) *Apis mellifera* (b) *Apis dorsata* (c) *Apis florea* (d) *Apis cerana* Answer: (a) *Apis mellifera* <div
- 26. Particles present inside nucleus are called nucleons. They include: protons neutrons Nucleons in Phosphorus Mass number of phosphorus: $$31$$ Hence phosphorus has: $$31 \text{ nucleons}$$
- 27. Intercalary meristems are meristematic tissues found between permanent tissues. They occur: at base of leaves at base of internodes Examples: Grasses Wheat Bamboo Ginger Difference from Other Meristems Meristem Location Function Apical meristem Root and shoot tips Increase in length Lateral meristem Sides of stem/root Increase in thickness Intercalary meristem Between mature tissues Regrowth and elongation Correction made: Intercalary meristem mainly helps elongation, not branch production.
- 28. (i) Dissimilar Elements in Same Group Some elements with unlike properties were placed in the same group in order to preserve periodicity. (ii) Position of Hydrogen Uncertain Hydrogen resembles both: alkali metals halogens (iii) Increasing Atomic Mass Order Not Strictly Followed Examples: Cobalt and Nickel Tellurium and Iodine (iv) No Position for Isotopes Isotopes have same chemical properties but different masses. (v) No Clear Explanation of Electronic Structure Mendeleev’s table did not explain the arrangement of electrons, and noble gases were not included in the original table.
- 29. (a) 13.7 billion years ago (b) 15 million years ago (c) 15 billion years ago (d) 20 million years ago Answer: (a) 13.7 billion years ago Modern estimate is approximately 13.8 billion years.
- 30. Forelimbs are modified into wings for flight. In some birds, forelimbs are modified for swimming, as in penguins. Hind limbs are adapted for perching, walking, running, swimming, wading or grasping prey. Examples: duck for swimming, heron for wading, ostrich for running and eagle for grasping with talons.
- 31. Features Largest animal phylum Bilaterally symmetrical Triploblastic and coelomate Body divided into: head thorax abdomen Jointed appendages present Exoskeleton made of chitin Moulting occurs Open circulatory system Respiration by: gills tracheae body surface Excretion by Malpighian tubules or green glands Examples Cockroach Crab Spider Scorpion Prawn Centipede
- 32. Soil with a pH of 5 is acidic soil, which requires treatment to raise its pH to a more neutral level suitable for most crops. Agricultural lime, such as calcium carbonate (CaCO₃) or quicklime (CaO), should be added to the acidic soil to neutralize the excess acidity and raise the soil pH. Calcium carbonate reacts with the acidic compounds in the soil and gradually increases the pH over time, while quicklime acts more rapidly. When adding lime to acidic soil, it is important to avoid using acid-forming fertilizers such as ammonium sulphate, as these would counteract the liming process and further acidify the soil. After the soil pH has been raised to an appropriate level through liming, su…
- 33. (a) fertilizers (b) pesticides (c) food colourants (d) preservatives Answer: (b) pesticides