based on Journalism and
Mass Communication.
Hindi Edition Code No. 1332 Rs. 90/-
Journalism
Journalism
&
Mass Communication
Mass Communication
Journalism
Journalism
&
Mass Communication
Mass Communication
Journalism
Journalism
&
Mass Communication
Mass Communication
C.S.V.
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February/
2008/
1665Physics
Q. What is a periodic wave function ?
☞ A wave function y (x, t) which satisfies the periodicity conditions of position and time is called a periodic wave function, i.e.
(i) y (x + m λ; t) = y (x, t) (ii) y (x, t + nt) = y (x, t) where λ = wavelength of wave, T = period of the wave n and m are integers.
Q. Heating system based on circulation of steam are more effi- cient in warming a building than those based on circulation of hot water. Explain why.
☞ Steam at 100°C possesses more heat than the same mass of water at 100°C. One gram of steam at 100°C possesses 540 calories of heat more than that possessed by 1 gm of water at 100°C. That is why heating systems based on circulation of steam are more efficient than those based on circulation of hot water.
Q. What is the relation between dielectric constant (K) and electric susceptibility (χχχχe) ?
☞ Relation between dielectric constant K and electric susceptibility χe is
K = 1 + χe.
Q. Why is electric power trans- mitted through A.C. and not D.C. ?
☞ Transformer is a device which can increase or decrease the A.C. voltage. We know that we transmit powerathighvoltagestoreducetrans- mission losses. Therefore, by using step-up transformers, we increases the voltage at generating station and step-down the voltage to 230 V at the distribution.Nosuchequivalentdevice of transformers is available in case of D.C. Therefore, we transmit power through AC and not D.C.
Q. What is the value of reduc- tion factor K of tangent galvano- meter ?
☞ K = 2 Hr
µ0n
where H = Horizontal component of earths magnetic field in tesla.
r = Radius of circular coil n = Number of turns in the
coil
Q. What is the function of grid in a triode valve ?
☞ The grid eliminates space charge and it controls the number of electrons reaching the plate and hence it is known as control grid.
Q. Explain why sun appears red at sun rise or sun set.
☞ At sunriseorsunset,thesunis near the horizon. Sunlight has to travel much greater distance than at noon. So, a much larger portion of the blue component of sunlight gets scattered away. Therefore, the light reaching the observer has a larger proportion of the remaining colours specially red.Hence, the sun appears red at sun rise or sun set.
Q. What does a welder protect against when he wears a mask ?
☞ The mask has a filter which absorbs the ultra-violet radiation pro- duced by the welding arc. This radia- tion is dangerous for the eyes.
Q. Does the relation V = iR apply to non-ohmic resistors ?
☞ Relation V = iR applies to non-ohmic resistors as well. For non- ohmic resistors, ‘R’ is not constant. It may noted that V = iR is not the statement of Ohm’s law. It is merely the definition of the resistance of a conductor whether it obeys Ohm’s law or not.
Q. Derive dimensional formula for electrical resistance and electri- cal conductance. ☞ [R] = [V] [I] = [Work done] [Charge] [I] = [ML 2T– 2] [AT] [A] = [ML2T–3A–2] Also R = ρAreaL where ρ is resistivity ρ = R × Area Length Conductance = 1 Resistivity = Length R × area Therefore, Conductance = [Length] [Resistance] [Area] = [L] [ML2T–3A–2] [L2] = [M–1L–3T3A2]
Q. Why is it easier to start a car engine on a warm day than on a chilly day ?
☞ The internal resistance of a car battery decreases with increase in temperature. Hence more current is drawn on a warm day and it becomes easier to start the engine.
Q. Why electrolytes have lower conductivity than metallic conduc- tors ?
☞ This is becauseofthefollow- ing two reasons :
(i) The number of ions in elec- trolyte is small compared to the number of free electrons in metallic conductors.
(ii) The mobility of ions in an electrolyte is small compared to the mobility of free electrons in a metallic conductor.
Chemistry
Q. How are colloidal impurities removedduringwaterpurification? ☞ The neutralisation of surface charge is used to precipitate colloidal impurities in water purification. When water is taken into municipal purifica- tion plants, it contains dispersed material such as colloidal clay. Clay particles are negatively charged, which keeps particles apart and dis- persed in water. To precipitate clay, aluminiumsaltssuchas Al2(SO4)3 are added.An aqueous solution, Al3+ ions
are hydrolysed to give [Al (H2O)6]3+
and other larger ions such as :
(H2O)4 Al Al (H2O)4 OH | O O | H 4+These highly charged ions are adsorbed onto the surface of the negatively charged colloidal particles, therebyneutralisingthesurfacecharge and allowing the colloidal particles to come together, and the clay precipi- tates from solution.
Q. Why does sulphur (density 2·1 g cm3), when carefully placed
on top of water, float while the same sinks in water when a few drops of detergent are placed on water ?
☞ Surface tension of water is affectedbyaddingdetergent.Thehigh surface tension of the water keeps more dense sulphur float on the water surface. When some drops of deter- gent are placed on the surface of water, the surface tension of water is reduced and the sulphur sinks to the bottom of the pot containing water.
Q. Why does even painstak- ingly purified water conducts electricity to a very small extent ?
☞ The existence of so-called
autoionization of water was proved
many years ago by Friedrich Kohlrauch. He found that even after water is painstakingly purified, it still conducts electricity to a very small extent, since autoionization produces very low concentration of H3O+ and
OH– ions even in the purest water.
2 H2O(l) H3O+
(aq) + OH–(aq)
Q. What biological function is performed by mineral apatite (cal- cium and phosphorus containing mineral) ?
☞ Hydroxy-apatite, Ca (OH)2.3 Ca3(PO4)2, is the main component of tooth enamel. Cavities in our teeth are formed when acids decompose the weakly basic apatite coating. This decaycanbe prevented by converting hydroxy-apatite to much more acid- resistant coating, fluorapatite, CaF2, 3 Ca3 (PO4)2, by adding a source of fluoride ion.
Q. What is the chemistry of usefulness of mortar ?
☞ Mortar consists of one part of lime to three parts of sand, with water added to make a thick paste. The very first reaction which occurs, is the hydrolysis or ‘slaking’ of the lime. Whenmortarisplacedbetween bricks or stone blocks, it slowly absorbs CO2 from air, and the slaked lime converts to calcium carbonate.
Ca(OH)2(s) + CO2(g)
→ CaCO3(s) + H2O(l) Although the sand in the mortar is chemically inert, the grains are bound together by the particles of CaCO3 and the hard material results.
Q. What is the thyroxine ? ☞ Itisnowknownthatthethyroid gland produces a growth regulating hormone, thyroxine which contains iodine. Thyroxine has following struc- ture : HO—C C— C | I | I H | C C — — C—O | H —C C C | I | I H | C C — — C— | H — — H2CH(NH )2 COOH. C
Most of the table salt sold in the market contains 0·01% NaI added to provide the necessary iodine in the diet.
Q. Cryolite is found in only small amounts in nature but large amount of cryolite is needed in production of Al. How is demand met with ?
☞ Most of the hydrogen fluoride (HF) produced by the reaction of fluorspar (CaF2) and H2SO4, is used to make cryolite.
CaF2(s) + H2SO4
→ CaSO4(s) + 2HF(g) 6 HF(aq) + Al(OH)3(s) + 3 NaOH
→ Na3AlF6(s) + 6 H2O(l) Cryolite
Q. Why cannot an electron exist inside the nucleus of an atom ?
☞ Suppose an electron exists insidethenucleus,thenits uncertainty inpositionwillbeofthesame order as the radius of the nucleus. The radius of the nucleus is of the order of 10–13
cm.Thentheuncertaintyin its velocity
∆v = h 4πm ×∆x = 6·62 × 10 – 27 4 × 3·14 × 9·1 × 10– 28 × 10–13 ≈ 5 × 1012 cm/sec
Thevelocityofelectronis greater than the velocity of light when it is present inside the nucleus. This condition is impossible and hence electron cannot exist in nucleus.
Q. What will be the average life of radium (Ra) if its t1/2 is 1690 years ?
☞ The reciprocal of radioactive decay constant, k is called the average life of a radioactive subs- tance. Average life (T) = 1 k We know that t1/2 = 0·693 k 1690 years = 0·693 k ∴ k = 0·693 1690 Hence average life,
T = 1690 0·693 = 2433·6 years or the value of 1 0·693 = 1·44 ∴ T = 1·44 × t1/2 = 1·44 × 1690 = 2433·6 years
Q. What is the basic difference between a sol and gel ?
☞ A colloidal solution in which dispersion medium is liquid and dis- persed phase is solid, then such a systemiscalled sol. For example gold sol and sulphur sol.
When the dispersion medium is solid and dispersed phase is liquid then the colloidal system is called gel. For example, boot polish, butter, gellies etc.
Q. What would be the vapour density (VD) of PCl5 if it is 90% dissociated at 250°°°°C ?
C.S.V.
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1667 ☞ As PCl5 is 90% dissociated at 250°Cand hence the degree of disso- ciation(α)ofPCl5willbe90/100=0·9. The molecular mass of PCl5 is 180·5 andhencethe theoretical V.D. of PCl5 will be 104·25. We know that α = DT – Do Do (Do observed V.D. of PCl5) Hence 0·9 = 104·25 – Do Do ∴ Do = 104·25 1·9 ≈ 54·8 Hence,thevapourdensityofPCl5 at 250°C will be 54·8.Q. What is the relation between equivalent mass and electroche- mical equivalent of a substance ?
☞ The equivalent mass of a substance is the mass of substance deposited by passage of one mole of electrons or one Faraday (96,500 C) of electricity.
Themassofsubstancedeposited by one coulomb is called electro- chemicalequivalent.Henceequivalent mass
= 96,500 × electrochemical equivalent Q. Whatwillbethe%composi- tion of a mixture of CO and CO2 whichonpassingoverredhotcoke registered a 25% increase in its volume ?
☞ We are aware of the following facts :
CO2 + C → 2 CO and CO + C → No reaction
Suppose the gaseous mixture contains x ml of CO2 and (100 – x) ml of CO gas.
From equation we can conclude that x ml CO2 produces 2x ml CO gas after passing on red hot coke.
Hence, the total volume of CO after reaction can be expressed as
100 – x + 2x = (100 + x) ml Given volume is increased by 25% and hence the final volume is 125 ml. Hence
100 + x = 125 ml
x = 25 ml
Thus, the mixture contains 25% CO2 and 75% CO gases.
Q. Using diazomethane as one of the reagents, how is acetic acid converted into propanoic acid ? What is this synthesis known as ?
☞ Theacidchlorideofaceticacid on reacting with diazomethane, an intermediate, diazoketone is formed. Diazoketone on losing nitrogen gives a ketene. When ketene is passed into water propanoic acid is formed.
CH3COOH →PCl5 CH3COCl Acetic acid CH2N2 → CH3— O || C—CH—N ≡ N Diazoketone CH3— O || C—CH—N ≡ N – N2 → CH3CH = C = O Ketene H2O → CH3CH2COOH Propanoic acid This reaction is known as Arnt
Eistert synthesis.
Zoology
Q. What is Trophic Level ? ☞ Trophic level is theoretical term in ecology. One of a succession of steps in the transfer of matter and energy through a community, as may be brought about by such events as grazing,predation,parasitism,decom- position. For theoretical and heuristic purposes,organismsare often treated as occupying the same trophic level when the matter and energy they containhavepassedthroughthesame number of steps since their fixation in photosynthesis. Primary producers, herbivores, primary, secondary and tertiary carnivores and decomposers all commonly figure as trophic levels intheanalysisofecosystems.Different developmental stages and/or sexes within a species may occur in more than one trophic level. The number of trophic levels in a community is thought to be limited by inefficiency in energy flow from one trophic level to the next; however, food chains are no longer in tropical communities, where energy input is high, than they are in Arctic communities, where energy input is low.
Q. What is Variation ?
☞ Variation is phenotypic and/or genotypic differences between indi- viduals of a population. Continuous
(qualitative) characters are those
exemplifiedthroughout the phenotypic range, tending to be determined by
polygenes. Discontinuous (quanti- tative) characters are those unrepre-
sented in all parts of the phenotypic range tending to be polymorphic, determined by genetic ‘switch- mechanisms’. Controversy over the relative influence of heredity and environment in producing phenotypic differences fuels the Nature—Nature debate. Problems arise in obtaining acceptable control populations to test hypothesis. By starting with geneti- cally uniform material (e.g., by cloning or repeated inbreeding) it is often possible to compare phenotypes pro- duced under different environmental regimes and to estimate heritability.
Q. What is Brain stem ? ☞ Brainstemisthestemlikepart of the brain that connects cerebral hemispheres with the spinal cord and comprises the medulla oblongata, the pons and the midbrain. Thus, the medulla oblongata, the pons and the midbrain lie in a portion of the brain known asthebrain stem. The medulla oblongata lies between the spinal cord and the pons and is anterior to the midbrain. It contains a number of vital centres for regulating heartbeat, breathing and vasoconstriction. It also contains the reflex centres for vomiting, coughing,sneezing, hiccups and swallowing. The pons contains bundles of axons travelling between the cerebellum and the rest of the central nervous system. In addition, the pons functions with the medulla to regulate the breathing rate and has reflex centres concerned with head movements in response to visual and auditory stimuli. Aside from acting as a relay station for tracts passing bet- ween the cerebrum and the spinal cord or cerebellum, the midbrain has reflex centres for visual, auditory and tactile responses.
Q. What are good and bad cholesterols ?
☞ In human blood, cholesterol is carried by special proteins, the lipo- proteins, which are manufactured in theliver.Two classes of these choles- terol containing lipoproteins are signi- ficant for the heart and blood vessels. Lowdensitylipoproteins(LDL)contain triglycerideandcholesterol.Ifcellsare in need of cholesterol for plasma
membranes or steroid hormone syn- thesis, they take up LDL. If this pro- cess does not occur, the LDL loaded with cholesterol remain in the plasma and deposition of cholesterol as plagues becomes possible. High den- sity lipoproteins (HDL) are the second group of lipoproteins. HDL picks up cholesterol from cells and transports it to the liver for disposal. The liver releases the excess cholesterol with the bile into the small intestine. It has been found that the higher HDL levels are associated with a fewer risk of developingatherosclerosis, while high LDL levels are associated with a higher risk. That is whyHDLhas been called ‘good’ cholesterol and LDL ‘bad’ cholesterol. LDL levels below 130 milligram per decilitre and HDL levels above 40 mg/dl are considered desirable.
Botany
Q. What do you mean by trace fossils ?
☞
Trace fossils are tracks, traits and burrows made by animals and found in ancient Sediments such as Sandstones, Shales or limestones. Very different biological activities of animals produce these biological structures. Study of trace fossils is knownasichnology or palichnologyand is a part of the Science of Palaeontology.
In the early years of Palaeon- tology, most of the ramified burrows creeping trails or other trace fossils were considered to be remains of marine algae. This is proven by many names ending ‘Phycus’ given to trace fossils. Generally palaeontology use for trace fossils the same bionomial nomenclature, with Latin names, as in naming animals and plants scien- tifically.
Q. What are fimbrie (pili) in certain bacteria ?
☞
Many gram negative bacteria have minute, hair like, straight and non-flagellar appendages called fimbrie or pili. They are given off from the cell surface and thinner than flagellum. Pili are composed entirely of protein known as Pilin. Their func- tion is attachment of bacteria to any plant or animal. During bacterial con- jugation, one or two sex pili from the male cells form bridges to the femalecell. The genetic material (DNA) is transferred form male bacterium to female bacterium along the groove of pili.
Fig. : Bacterial cell showing the distribution of pili.
Q. What do you mean by essential oil ?
☞
The essential oils are odori- ferous, oily products of plant origin which are distillable. They occur in leaves, twig, fruit, blossoms, root and trunk of plants. The principal cons- tituents of essential oils are the terpenes. Benzenoid and aliphatic compounds may also be present. Most of the constituents are hydro- carbons and oxygenated derivatives of hydrocarbons. A few contain sul- phur andnitrogen. For example, oil of mustardcontains organic isothio-cyanate; garlic and onion oils contain
organic sulphides. Anthranilates,
indole and skatole sometimes occur
in small amounts. Most essential oils are exceedingly complex mixtures of non-terpene and terpene ingredients.
Q. What do you mean by rusts and smuts fungi ?
☞
Rusts and smuts are club fungi. They parasitize cereal crops such as rye, wheat, corn and oat. Rusts and smuts do not form basi- diocarps and their spores are small and numerous, resembling shoot. Some smuts enter seeds and exist inside the plant, becoming visible only near maturity. Some other smuts externally infect plants. In corn smuts, the mycelium grows between the corn kernels and secretes substances that cause the development of tumours on the ears of corn.The life cycle of rusts often requires two different plant host species to complete the cycle. Black
stem rust of wheat uses barberry
plant leaves as an alternate host and
blister rust of white pine uses
current and gooseberry bushes. The
black rust of wheat is caused by
Puccinia graminis-tritici, which is a
heteroecious parasite.
Q. Whatarehistones?Givethe molecular weight of H3 and H4
histones. In which type of histone the largest amount of arginine is found ?
☞
The DNA in the chromatin is very highly associated with proteins called histones, which package and order the DNA into structural units called nucleosomes. Histones have molecular weight of between 11,000 and 21,000 and are very rich in the basic amino acidsarginine and lysine. The H3 histones are nearly iden- tical in amino acid sequence in all eukaryotes, as are the H4 histones, suggesting strict conservation of their functions.HistoneH4 bearsthelargest amount of argine (about 14%).Q. What is cytochrome and its application ?
☞
Cytochrome is a complex protein occurring withincells of a wide variety of animals and plants. The integral part of a cytochrome is a heme (iron tetrapyrrole) moiety. The heme imparts generally red colour to the cytochrome, as well as charac- teristic absorption bands which are used for the spectroscopic observa- tion and identification of these intra- cellular hemoproteins. The iron atom of the heme may be reduced and oxidized by appropriate substances in the cell, thus constituting the function ofthecytochromeaselectroncarriers.Q. What does a cell face chal- lenges while it undergoes a great increase in size ?
☞
Under such conditions, many portion of the cell may well suffer deprivation of vital fuel materials or the essential molecules as a result of enlargement. The cell must exchange materials with the environment across the surface membrane. An increase cell size will result in a greater increase in volume and mass than in surface area, so that the cell wall lose effective exchange capacity. This will impose restriction on the amount of food and oxygen that can move across the membrane to service the metabolic needs of the increased living mass in the interior. The distri- bution of materials by diffusion will also take longer as the cell grows larger.C.S.V.
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1669CSV Crossword–20
1 2 3 4 5 6 7 8 9 10 11 13 19 17 18 20 21 22 23 24 14 15 13 16 Across :1. A long thin solenoid turned into a ring (6). 4. A mathematical entity, an array (6). 8. Unit of 1/(Capacitance) (5).
9. Geiger and ……… bombarded thin gold foils with Alpha particles, on suggestions of Ernest Rutherford (7).
10. His mass spectrograph was very important (5). 11. Essentially oxygen, molecular weight = 48 (5). 14. A supplementary unit (9).