Pariksha SaathiGeneral Studies
General Science: Practice Questions with Answers
480 practice questions on General Science, with answers; most also have an explanation or a worked solution. Try each one before you open its answer.
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Q.251
Sound travels fastest in which of the following?
- A Air
- B Vacuum
- C Water
- D Steel
Show answer
Correct answer: (D) Steel
Sound is a mechanical wave that needs a medium; it travels fastest in solids (about 5000 m/s in steel), slower in water (about 1500 m/s) and slowest in air (about 340 m/s). It cannot travel through vacuum at all.
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Q.252
Dried raisins kept in plain water for some time swell up. Water enters the raisins by
- A Plasmolysis
- B Osmosis
- C Transpiration
- D Guttation
Show answer
Correct answer: (B) Osmosis
Water moves through the selectively permeable membranes from the dilute water outside into the more concentrated cell contents; this is osmosis (endosmosis). Plasmolysis is the shrinking of cell contents when a cell loses water.
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Q.253
The fuse wire used in household electric circuits should have
- A Low melting point and high resistance
- B High melting point and low resistance
- C High melting point and high resistance
- D Low melting point and low resistance
Show answer
Correct answer: (A) Low melting point and high resistance
A fuse must heat up and melt quickly when excess current flows, so it is made of a tin-lead alloy with low melting point and high resistance. It is always connected in series with the live wire.
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Q.254
Which plant hormone inhibits growth and has effects that include the wilting of leaves?
- A Gibberellin
- B Abscisic acid
- C Cytokinin
- D Auxin
Show answer
Correct answer: (B) Abscisic acid
Abscisic acid is a growth-inhibiting hormone; wilting of leaves is one of its effects. Auxin, gibberellin and cytokinin all promote growth in different ways.
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Q.255
When an iron nail is kept in copper sulphate solution for some time, the blue colour of the solution fades and a brownish coating forms on the nail. This shows that
- A copper is more reactive than iron
- B iron and copper are equally reactive
- C iron is more reactive than copper
- D iron does not react with salts of other metals
Show answer
Correct answer: (C) iron is more reactive than copper
Fe + CuSO₄ → FeSO₄ + Cu. Being more reactive, iron displaces copper from its salt solution; the brown coating is copper, and the solution turns pale green as iron sulphate forms.
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Q.256
Which of the following metals does not react with water, even in the form of steam?
- A Sodium
- B Magnesium
- C Iron
- D Copper
Show answer
Correct answer: (D) Copper
Copper does not react with cold water, hot water or steam. Sodium reacts violently with cold water, magnesium reacts with hot water, and iron reacts with steam to form iron oxide and hydrogen.
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Q.257
Vinegar, used as a preservative in pickles, is a 5-8% solution of which acid in water?
- A Methanoic acid
- B Citric acid
- C Lactic acid
- D Ethanoic acid
Show answer
Correct answer: (D) Ethanoic acid
Vinegar is a 5-8% solution of ethanoic acid (acetic acid, CH₃COOH) in water and is widely used as a preservative in pickles.
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Q.258
Danger signal lights are red because red light
- A is scattered the most by fog and smoke
- B is scattered the least by fog and smoke
- C has the highest frequency in visible light
- D is completely absorbed by fog
Show answer
Correct answer: (B) is scattered the least by fog and smoke
Red has the longest wavelength in visible light, so it is scattered the least by fog, smoke and air particles and can be seen from far away. It has the lowest, not the highest, frequency of visible light.
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Q.259
In plants, the xylem tissue transports
- A Water and minerals from the roots to the leaves
- B Prepared food from the leaves to other parts
- C Hormones only
- D Oxygen from the leaves to the roots
Show answer
Correct answer: (A) Water and minerals from the roots to the leaves
Xylem, made of dead vessels and tracheids, carries water and dissolved minerals upwards; phloem, made of living sieve tubes, carries prepared food in both directions. Together they form the vascular tissue.
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Q.260
If the distance between two masses is doubled, the gravitational force between them becomes
- A one-fourth
- B half
- C double
- D four times
Show answer
Correct answer: (A) one-fourth
Gravitational force F = Gm₁m₂/r² varies inversely as the square of the distance. Doubling r makes the force 1/2² = 1/4 of its original value.
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Q.261
The depletion of the ozone layer is mainly caused by synthetic chemicals used as refrigerants and in fire extinguishers, known as
- A Carbon dioxide
- B Methane
- C Sulphur dioxide
- D Chlorofluorocarbons (CFCs)
Show answer
Correct answer: (D) Chlorofluorocarbons (CFCs)
CFCs released into the air reach the upper atmosphere, where they break down ozone molecules. Their production has been sharply cut under international agreements to protect the ozone layer.
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Q.262
The general formula of alkanes, the saturated hydrocarbons, is
- A CnH2n+2
- B CnH2n
- C CnH2n-2
- D CnHn
Show answer
Correct answer: (A) CnH2n+2
Alkanes contain only single bonds and follow CnH2n+2, e.g. methane CH₄ and ethane C₂H₆. CnH2n is the general formula of alkenes and CnH2n-2 that of alkynes.
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Q.263
Which of the following statements about respiration is correct?
- A Anaerobic respiration releases more energy from glucose than aerobic respiration
- B Aerobic respiration breaks glucose down completely into carbon dioxide and water
- C Aerobic respiration takes place in the absence of oxygen
- D Anaerobic respiration occurs only in plants
Show answer
Correct answer: (B) Aerobic respiration breaks glucose down completely into carbon dioxide and water
In aerobic respiration glucose is completely broken down to carbon dioxide and water, releasing much more energy than anaerobic respiration. Aerobic respiration needs oxygen, and anaerobic respiration also occurs in yeast and in our own muscle cells.
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Q.264
Malaria is caused by a
- A Bacterium
- B Virus
- C Protozoan
- D Fungus
Show answer
Correct answer: (C) Protozoan
Malaria is caused by the protozoan Plasmodium, transmitted by the bite of the female Anopheles mosquito; Ronald Ross proved the mosquito link. Quinine from cinchona bark is its classic drug.
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Q.265
The modern periodic table arranges elements in increasing order of their
- A Atomic number
- B Atomic mass
- C Atomic volume
- D Number of neutrons
Show answer
Correct answer: (A) Atomic number
Moseley's modern periodic law states that the properties of elements are a periodic function of their atomic number. Mendeleev's original table was based on atomic mass.
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Q.266
A short circuit in domestic wiring occurs when
- A too many appliances are connected to a single socket
- B the earth wire gets disconnected from an appliance
- C the live wire and the neutral wire come into direct contact
- D the supply voltage falls suddenly
Show answer
Correct answer: (C) the live wire and the neutral wire come into direct contact
When the live and neutral wires touch, the resistance of the circuit becomes almost zero and a very large current flows; this is a short circuit. Connecting too many appliances to one socket is called overloading.
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Q.267
Food cooks faster in a pressure cooker because
- A the increased pressure raises the boiling point of water, so cooking takes place at a higher temperature
- B the increased pressure lowers the boiling point of water
- C the food is kept away from air
- D the metal of the cooker produces extra heat of its own
Show answer
Correct answer: (A) the increased pressure raises the boiling point of water, so cooking takes place at a higher temperature
The boiling point of water rises when the pressure on it increases. Steam trapped in the cooker raises the pressure inside, so the water boils above 100 °C (at about 120 °C in a typical cooker), and food cooks faster at this higher temperature. For the same reason, water boils below 100 °C at hill stations, where the air pressure is lower, and cooking there takes longer.
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Q.268
Who showed in 1913 that the atomic number of an element is a more fundamental property than its atomic mass, leading to the Modern Periodic Law?
- A Henry Moseley
- B Dmitri Mendeleev
- C John Newlands
- D Johann Döbereiner
Show answer
Correct answer: (A) Henry Moseley
Henry Moseley showed that atomic number is the more fundamental property, and the periodic law was revised accordingly: the properties of elements are a periodic function of their atomic number.
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Q.269
The junction between the end of the axon of one neuron and the dendrite of the next neuron, across which the nerve impulse is passed on, is called the
- A Myelin sheath
- B Synapse
- C Cell body
- D Node of Ranvier
Show answer
Correct answer: (B) Synapse
A synapse is the tiny gap between the axon ending of one neuron and the dendrite of the next; chemicals released at the axon ending carry the impulse across it. The myelin sheath is the insulating cover of the axon and the cell body contains the nucleus.
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Q.270
Which is the largest phylum of the animal kingdom, whose members have jointed legs?
- A Annelida
- B Mollusca
- C Arthropoda
- D Chordata
Show answer
Correct answer: (C) Arthropoda
Arthropoda ('jointed legs') is the largest group of animals and includes insects, spiders, prawns and centipedes. Annelids such as the earthworm have segmented bodies but no jointed legs.
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Q.271
Woollen clothes keep us warm in winter mainly because
- A woollen clothes produce heat of their own
- B wool is a good conductor of heat
- C air trapped between the wool fibres is a poor conductor of heat and reduces the loss of body heat
- D woollen clothes absorb heat from the cold air around us
Show answer
Correct answer: (C) air trapped between the wool fibres is a poor conductor of heat and reduces the loss of body heat
Wool fibres trap a lot of air between them. Air is a poor conductor of heat, so this layer slows the flow of heat from the warm body to the cold surroundings. Woollen clothes do not produce heat; they only reduce the loss of body heat.
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Q.272
Which of the following is absent in mature red blood cells of humans?
- A Cell membrane
- B Haemoglobin
- C Cytoplasm
- D Nucleus
Show answer
Correct answer: (D) Nucleus
Mature human red blood cells lose their nucleus, which leaves more room for haemoglobin to carry oxygen. They are disc-shaped and bounded by a cell membrane.
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Q.273
A fielder pulls his hands backward while catching a fast cricket ball. He does this to
- A make the momentum of the ball become zero more quickly
- B increase the time taken to stop the ball, so that the force on his hands is reduced
- C increase the force applied by the ball
- D change the mass of the ball
Show answer
Correct answer: (B) increase the time taken to stop the ball, so that the force on his hands is reduced
Force = change in momentum ÷ time. Pulling the hands back increases the time in which the ball's momentum becomes zero, so a smaller force acts on the hands.
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Q.274
Which vitamin contains the metal cobalt?
- A Vitamin B12
- B Vitamin K
- C Vitamin A
- D Vitamin D
Show answer
Correct answer: (A) Vitamin B12
Vitamin B12 (cobalamin) has a cobalt atom at its centre, and its deficiency causes a type of anaemia. For comparison, iron is present in haemoglobin and magnesium in chlorophyll.
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Q.275
The Haber process is used for the industrial manufacture of
- A Sulphuric acid
- B Nitric acid
- C Ammonia
- D Methanol
Show answer
Correct answer: (C) Ammonia
In the Haber process nitrogen and hydrogen combine at about 450 degrees C and 200 atmospheres over an iron catalyst to form ammonia. Nitric acid is made by the Ostwald process.
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Q.276
Which part of the brain controls body balance and the coordination of muscular movements?
- A Cerebrum
- B Medulla oblongata
- C Hypothalamus
- D Cerebellum
Show answer
Correct answer: (D) Cerebellum
The cerebellum maintains posture and balance; alcohol affects it and causes staggering. The cerebrum is the seat of intelligence and memory, the medulla controls heartbeat and breathing, and the hypothalamus controls body temperature and hunger.
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Q.277
The human heart has how many chambers?
- A Two
- B Three
- C Four
- D Five
Show answer
Correct answer: (C) Four
Mammals and birds have a four-chambered heart (two atria and two ventricles) that keeps oxygenated and deoxygenated blood separate. Fish have a two-chambered and amphibians a three-chambered heart.
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Q.278
Arrange the following atomic models in the chronological order in which they were proposed: Bohr's model, Dalton's atomic theory, Rutherford's nuclear model, Thomson's plum-pudding model
- A Dalton, Rutherford, Thomson, Bohr
- B Dalton, Thomson, Rutherford, Bohr
- C Thomson, Dalton, Bohr, Rutherford
- D Thomson, Rutherford, Dalton, Bohr
Show answer
Correct answer: (B) Dalton, Thomson, Rutherford, Bohr
Dalton (1808) proposed the indivisible atom, Thomson (1904) the plum-pudding model after discovering the electron, Rutherford (1911) the nucleus from the gold-foil experiment, and Bohr (1913) electrons in fixed orbits.
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Q.279
One kilowatt-hour (1 kWh), the commercial unit of electrical energy, is equal to
- A 3.6 x 10^6 joule
- B 3.6 x 10^5 joule
- C 3.6 x 10^3 joule
- D 36 x 10^4 joule
Show answer
Correct answer: (A) 3.6 x 10^6 joule
1 kWh = 1000 W x 3600 s = 3.6 x 10^6 J. This is the 'one unit' printed on electricity bills.
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Q.280
Atoms of the same element having the same atomic number but different mass numbers are called
- A Isobars
- B Isotopes
- C Isotones
- D Allotropes
Show answer
Correct answer: (B) Isotopes
Isotopes (for example protium, deuterium and tritium of hydrogen) differ only in the number of neutrons. Isobars have the same mass number but different atomic numbers, such as Ar-40 and Ca-40.
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Q.281
Water kept in an earthen pot (matka) stays cool in summer because
- A clay is a good conductor of heat
- B clay reflects all the sunlight falling on it
- C the pot absorbs heat from its surroundings
- D water seeping out through the pores evaporates, taking latent heat from the remaining water
Show answer
Correct answer: (D) water seeping out through the pores evaporates, taking latent heat from the remaining water
Water oozing through the tiny pores evaporates from the outer surface. Evaporation needs latent heat, which is drawn from the pot and the water inside, so the water cools; this is cooling by evaporation.
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Q.282
The age of fossils can be estimated by
- A Measuring their weight
- B Measuring the ratio of radioactive isotopes such as carbon-14 in them
- C Counting the number of cells in them
- D Testing their hardness
Show answer
Correct answer: (B) Measuring the ratio of radioactive isotopes such as carbon-14 in them
Fossils are dated by finding the ratios of different isotopes of the same element in them (radioactive or carbon dating), because a radioactive isotope decays at a fixed rate. The depth of the rock layer in which they are found also gives a rough idea.
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Q.283
Which of the following statements about resistivity is correct?
- A It doubles when the length of the wire is doubled
- B It increases when the wire is made thinner
- C It depends on the nature of the material and its temperature
- D Its SI unit is ohm per metre
Show answer
Correct answer: (C) It depends on the nature of the material and its temperature
Resistivity is a property of the material; it changes with temperature but not with the length or thickness of the wire. Its SI unit is ohm metre (Ω m), not ohm per metre.
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Q.284
X-rays were discovered by
- A Wilhelm Roentgen
- B Henri Becquerel
- C Marie Curie
- D Ernest Rutherford
Show answer
Correct answer: (A) Wilhelm Roentgen
Roentgen discovered X-rays in 1895 and received the first Nobel Prize in Physics in 1901. Becquerel discovered radioactivity, and Marie Curie isolated radium and polonium.
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Q.285
Which of the following statements about meiosis is correct?
- A It occurs in all body cells to bring about growth and repair
- B It produces two daughter cells identical to the parent cell
- C It halves the chromosome number and produces four daughter cells
- D It keeps the chromosome number of the daughter cells equal to that of the parent
Show answer
Correct answer: (C) It halves the chromosome number and produces four daughter cells
Meiosis (reduction division) occurs only in reproductive cells and produces four haploid gametes with half the chromosome number, so that fertilisation restores the diploid number. Mitosis in body cells gives two identical cells for growth and repair.
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Q.286
The total force acting on a surface in a direction perpendicular to it is called
- A pressure
- B tension
- C thrust
- D friction
Show answer
Correct answer: (C) thrust
The force acting perpendicular to a surface is called thrust, and its unit is the newton. Pressure is the thrust acting per unit area.
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Q.287
Ribosomes in a cell are the site of
- A Lipid synthesis
- B Starch storage
- C Photosynthesis
- D Protein synthesis
Show answer
Correct answer: (D) Protein synthesis
Ribosomes, found free in the cytoplasm or attached to the rough endoplasmic reticulum, are the sites where proteins are made from amino acids. Photosynthesis takes place in chloroplasts.
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Q.288
Which statement about urine formation in the nephron is correct?
- A Filtration of blood takes place in the collecting duct
- B Urea is completely reabsorbed into the blood
- C Glucose, amino acids, salts and much water are selectively reabsorbed from the filtrate
- D Urine is formed in the urinary bladder
Show answer
Correct answer: (C) Glucose, amino acids, salts and much water are selectively reabsorbed from the filtrate
As the filtrate flows along the tubule, useful substances such as glucose, amino acids, salts and a major amount of water are selectively reabsorbed. Filtration occurs in the glomerulus, urea is not completely reabsorbed but passes out in urine, and the bladder only stores urine.
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Q.289
Which of the following was a limitation of Mendeleev's periodic table?
- A He left gaps for elements that had not yet been discovered
- B Noble gases, discovered later, could be placed in a new group without disturbing the order
- C He predicted the properties of some undiscovered elements
- D It could not explain the position of isotopes of an element
Show answer
Correct answer: (D) It could not explain the position of isotopes of an element
Isotopes have different atomic masses but the same chemical properties, so an arrangement based on atomic mass could not give them a proper place. Leaving gaps, predicting new elements and fitting in the noble gases were strengths of his table.
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Q.290
At the highest point of its path, a ball thrown vertically upward has
- A zero velocity and zero acceleration
- B maximum velocity and zero acceleration
- C zero velocity and an acceleration g directed downward
- D zero velocity and an acceleration g directed upward
Show answer
Correct answer: (C) zero velocity and an acceleration g directed downward
At the top the ball stops for an instant, so its velocity is zero, but gravity still acts on it, so its acceleration is g directed downward. That is why it immediately starts falling back.
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Q.291
Cuscuta (amarbel) grows on other plants and draws its food from them. Its mode of nutrition is
- A Autotrophic
- B Parasitic
- C Saprophytic
- D Insectivorous
Show answer
Correct answer: (B) Parasitic
Cuscuta is a parasite: it takes ready-made food from its host plant and harms the host. Saprophytes feed on dead and decaying matter, and autotrophs make their own food.
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Q.292
An electric motor lifts a load of mass 50 kg through a height of 10 m in 5 s. Taking g = 10 m/s² and ignoring losses, the power of the motor is
- A 1000 W
- B 250 W
- C 100 W
- D 2500 W
Show answer
Correct answer: (A) 1000 W
Work done = mgh = 50 × 10 × 10 = 5000 J. Power = work ÷ time = 5000 ÷ 5 = 1000 W (1 kW).
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Q.293
Which of the following instrument-quantity pairs is correctly matched?
- A Hygrometer - atmospheric pressure
- B Anemometer - humidity of air
- C Barometer - atmospheric pressure
- D Ammeter - potential difference
Show answer
Correct answer: (C) Barometer - atmospheric pressure
A barometer measures atmospheric pressure. A hygrometer measures humidity, an anemometer measures wind speed and an ammeter measures electric current; potential difference is measured by a voltmeter.
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Q.294
The cell wall of fungi is made of a tough complex sugar called
- A Cellulose
- B Lignin
- C Pectin
- D Chitin
Show answer
Correct answer: (D) Chitin
Fungal cell walls are made of chitin, the same tough material that forms the exoskeleton of insects. Plant cell walls are made mainly of cellulose, and lignin hardens the walls of woody plant cells.
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Q.295
In the food chain grass → grasshopper → frog → snake, a non-biodegradable pesticide sprayed on the grass will be found in the highest concentration in the
- A Grass
- B Grasshopper
- C Frog
- D Snake
Show answer
Correct answer: (D) Snake
Non-biodegradable chemicals are not broken down or excreted easily, so they build up in the body and their concentration increases at each higher trophic level. This is biological magnification, so the snake, at the top of the chain, has the most.
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Q.296
The opening and closing of the stomata (tiny pores) on a leaf is controlled by the
- A Root hairs
- B Companion cells
- C Xylem vessels
- D Guard cells
Show answer
Correct answer: (D) Guard cells
Each stoma is surrounded by a pair of guard cells. When water flows into them they swell and the pore opens; when they lose water they shrink and the pore closes.
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Q.297
Kwashiorkor, in which a child shows stunted growth, swelling of the face and body and discoloured hair, is caused by the deficiency of
- A Vitamin A
- B Protein
- C Iodine
- D Calcium
Show answer
Correct answer: (B) Protein
Kwashiorkor occurs when a child's diet lacks enough protein for a long period. Marasmus, in which the child becomes extremely thin and weak, results when both proteins and carbohydrates are lacking.
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Q.298
The first step of respiration, the breakdown of glucose into pyruvate, takes place in the
- A Mitochondria
- B Cytoplasm
- C Nucleus
- D Golgi apparatus
Show answer
Correct answer: (B) Cytoplasm
Glucose, a six-carbon molecule, is first broken into pyruvate, a three-carbon molecule, in the cytoplasm, whether or not oxygen is present. In aerobic respiration the pyruvate is then broken down further in the mitochondria.
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Q.299
Polythene is a polymer made by joining together a very large number of molecules of
- A Methane
- B Ethene
- C Ethanol
- D Propane
Show answer
Correct answer: (B) Ethene
The monomer of polythene (polyethene) is ethene, CH₂=CH₂; its double bond opens up during polymerisation so that the units join into long chains. Methane, ethanol and propane have no double bond and do not polymerise in this way.
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Q.300
Bile, produced by the liver, helps in digestion by
- A Emulsifying fats into smaller globules
- B Breaking down proteins into amino acids
- C Converting starch into sugar
- D Absorbing water from undigested food
Show answer
Correct answer: (A) Emulsifying fats into smaller globules
Bile is made in the liver and stored in the gall bladder. Its bile salts break large fat globules into smaller ones (emulsification) so that lipase can act efficiently; bile also makes the food coming from the stomach alkaline.
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How these questions were made
Authored by an AI assistant (Claude) from its own general knowledge of stable, well-established facts (no live lookup) - not reviewed by a subject-matter expert; verify against an official source before relying on any fact.