SECTION - I (MARKS : 15) · PDF fileSURA BOOKS MARCH - 2017. Public Exam Question Paper with Answers [Time Allowed : 2.30 Hours] SCIENCE [Maximum Marks : 75] SECTION - I (MARKS : 15)

SURA BOOKS

MARCH - 2017Public Exam Question Paper with Answers

[Time Allowed : 2.30 Hours] SCIENCE [Maximum Marks : 75]

SECTION - I(MARKS : 15)

Note:(i) Answer all the 15 questions. 15 × 1 = 15 (ii) Choose the correct answer from the alternatives given in the brackets.

1. In persons suffering from insulin-dependent diabetes, _____ the cells of pancreas are degenerated.(Alpha, Beta, Gamma, Delta)

2. Thefirstvaccineinjectedintoajustbornbabyis________(Oral polio, DPT, DPT and Oral polio, BCG)

3. Theendocrineglandrelatedtotheimmunesystemis___________.(Thyroid,Thymus,Adrenal,Pineal)

4. If a water soaked seed is pressed, a small drop of water comes out through the __________.(Stomata,Lenticel,Micropyle,Radicle)

5. Mitralvalveisfoundbetween_________.(Rightauricleandrightventricle,Leftauricleand leftventricle,Rightventricleandpulmonaryartery,Leftventricleandaorta)

6. Inmonotropathespecialtypeofrootwhichabsorbsnourishmentisthe_______.(Haustoria,Mycorrhizalroot,Clingingroot,Adventitiousroot)

7. Thesedimentedandfloatingmaterialsareremovedbythistreatmentprocess.(Primarytreatment,Secondarytreatment,Tertiarytreatment,Peripheraltreatment)

8. Themixtureofgasesusedbydeep-seadiversis________.(helium-oxygen,oxygen-nitrogen,hydrogen-nitrogen)

9. Vinegar is present in acetic acid. Curd contains _____ acid.(Lactic acid, Tartaric acid, Citric acid)

10. An element which is an essential constituent of all organic compounds belongs to the ______ group.(14th group, 15th group, 16th group)

11. _________ is used for coagulating rubber from latex.(Ethanol, Ethanoic acid)

12. ScrewGaugeisaninstrumentusedtomeasurethedimensionsofverysmallobjectsupto________ .(0.1 cm., 0.01 cm., 0.1 mm., 0.01 mm)

[ 1 ]

10th

STD.

SURA's Guides for 3rd to 12th Std for all Subjects in TM & EM Available

www.surabooks.com Sura's Will to Win Guides For Contact 9600175757

www.Padasalai.Net www.TrbTnpsc.com

http://www.trbtnpsc.com/2016/03/10th-12th-public-exam-answer-keys.html

www.Padasalai.Net

SURA BOOKS

2 Sura’s Science – X Std. Public Exam Question Paper - March 2017 with Answers

13. Thephysicalquantitywhichisequaltorateofchangeofmomentumis________.(displacement, acceleration, force, impulse)

14. Kilowatt–hour is the unit of ________.(potentialdifference,electricpower,electricenergy,charge)

15. An electric current through a metallic conductor produces _________ around it.(magneticfield,mechanicalforce,inducedcurrent)

SECTION - II

(MARKS : 40)Note : Answer any twenty questions. 20 × 2 = 4016. Theinheritablecharactersvaryindifferentspeciesandwithinthesamespecies.Name

thevariationinthefollowingcases: (i) Theeyecolouramongthehumanbeingsarevariedasblue,black,brown,green,

etc.Thisiscalledas________variation. (ii) The dentition in the rabbit and the elephant are not the same. This is called as

________variation.17. What is Genetic Engineering?18. Matchthefollowingbyidentifyingthepair: (medicines, fuel, microbes, metabolism, organic acids) (i) Vaccine, (ii) Naturalgas, (iii) Citricacid, (iv) Vitamins19. MarasmusandKwashiorkararebothproteindeficiencydefects.Marasmusdiffersfrom

Kwashiorkarinenlargedbellyandswellingintheface.Arethesesymptomsfortheabovediseases correct? If not, correct it.

20. Copythediagramandlabelthepartswiththehelpofthecluesgiven:

(i) It is otherwise called supra renal gland. (ii) Itsecretestwohormones,namelyaldosteroneandcortisone.21. Drawthegivendiagramandlabelthefollowingparts. (i) Exine (ii) Tube nucleus





www.Padasalai.Net

SURA BOOKS

Sura’s Science – X Std. Public Exam Question Paper - March 2017 with Answers 3

22. Mentionanyfouradaptationsseeninthecamelsothatitcanlivesuccessfullyindeserts.23. Pick out the odd one out. (i) globulin,glomerulus,fibrinogen,albumin (ii) mountaingoat,bighornedsheep,grizzlybear,seal24. Completethetablegivenbelow:

Excretory organ Disposed as Excretory productsKidneys Urine Nitrogenouswasteproducts-

Urea, Uric acid, Creatinine etc.Lungs Exhaled / Expired air __________Skin __________ Excess water and salts

25. Observethediagram. (i) MentionthetypeofmovementsshowninfigureAandB. (ii) Howdoesthemovementdifferfromthemovementofmimosa?

26. Sugarsolutionisconvertedintoalcohol. (i) Intheabovereactionwhatkindofprocesstakesplace? (ii) Whichmicro-organismisinvolved?27. Matchthefollowing:

A B(a) Ammonotelic (i) annelids(b) Ureotelic (ii) fish(c) Uricotelic (iii) mammal(d) Nephridia (iv) birds





www.Padasalai.Net

SURA BOOKS


28. Depictafoodchainbyplacingthefollowingorganismsinthecorrecttrophiclevels: (Snake, Grass, Eagle, Frog, Grasshopper) 29. Whatarethevariousliquidbiofuelsfortransportation?(Anyfour)30. Match the suitable renewable and non-renewable sources.

Sources A B CRenewable Coal Wind PetroleumNon–Renewable Hydrogen Naturalgas Solarenergy

31. Fossilfuelsareformedbydecompositionofbiomassburiedundertheearthovermillionsofyearsago.Nameanytwofossilfuels.

32. WhatisBrownianmovement?33. Find the concentration of solution in terms of weight percent if 20 g of common salt is

dissolvedin50gofwater.34. Calculate number of moles in 12.046 × 1022 atoms of copper.35. Two acids ‘A’ and ‘B’ were kept in beakers. Acid ‘A’ undergoes partial dissociation in

water, whereas acid ‘B’ undergoes complete dissociation in water. (i) Of the two acids ‘A’ and ‘B’ , which is weak acid and which is strong acid? (ii) Giveoneexampleforweakacidandstrongacid.36. Picktheoddoneout: (i) Inorganicacid:HCl,HNO3, H2SO4, HCOOH (ii) BasicNature:Blood,BakingSoda,Vinegar,Householdammonia.37. Correctthemistakes,ifanyinthefollowingstatement. (i) Secondperiodisashortperiod.Itcontainsonlytwoelements. (ii) Group18elementsarecalledHalogenfamily.38. Assertion : Agreenishlayerappearsoncoppervessels,ifleftuncleaned. Reason : Itisduetotheformationofalayerofbasiccoppercarbonate. (a) Assertionandreasonarecorrectandrelevanttoeachother. (b) Assertionistruebutreasonisnotrelevanttotheassertion.39. Anorganiccompound(A)iswidelyusedasapreservativeinpickleandhasamolecular

formula C2H4O2. This compound reacts with ethanol to form a sweet smelling compound (B).

(i) IdentifythecompoundsAandB. (ii) Nametheprocessandwritecorrespondingchemicalequation.





www.Padasalai.Net

SURA BOOKS


40. Assertion (A) : MRIisusedtoscantheinnerorgansofhumanbodybypenetratingveryintensemagneticfield.

Reason (R) : Byuseofveryintensemagneticfield,veryhighresolutionimagescanbe obtained.

(a) (A) is incorrect and (R) is correct. (b) (A) is correct and (R) is incorrect. (c) Both (A) and (R) are incorrect. (d) (A) is correct and (R) supports (A).41. Anobjectofmass1kgisdroppedfromaheightof20m.Ithitsthegroundandrebounds

with the same speed. Find the change in momentum. (Take g = 10 m/s2)42. Matchthefollowing:

COMPONENTS SYMBOLS(a) An electric cell (i)

(b) Plugkey(or)switch(closed) (ii) + -

(c) Awirejoint (iii)

(d) AresistorofresistanceR (iv) ( )

43. Fill in the blanks. (i) Potential difference : Voltmeter ; then Current : ________ (ii) Hydro power plant : Conventional source of energy ; then Solar energy : ________44. Writeaboutoceanthermalenergy.45. Theraydiagramshownbelowisintroducedtoshowhowaconcavemirrorforms the

imageofanobject. (a) Identify themistake and draw the correct ray

diagram. (b) Writethejustificationsforyourcorrections.

46. DefineFleming’srighthandrule.47. Ifanobjectisplaced25cminfrontoftheconverginglensformsanimage20cmbehind

the lens, then what is the focal length of the lens?

C F P

N

M





www.Padasalai.Net

SURA BOOKS


SECTION - III

(MARKS : 20)Note: (i) Answer any four questions by choosing one question from each part. (ii) Each question carries five marks. (ii) Draw diagrams wherever necessary. 4 × 5 = 20

PART - I48. Thereisawidespreadoutbreakofmalariainyourarea. (a) Suggest some controlling measures to the local authorities concerned. (b) Writethesymptomsformalaria.49. (a) Usewordsfromthegivenlisttocompletethefollowingparagraph. (Vertebral column, Piamater, Arachnoid membrane, Meninges, Duramater) Thecentralnervoussystemiscoveredbythreeprotectivecoveringscollectively

called___(1)____.Theoutermostcoverlyingbelowtheskulland____(2)____is double thick and is called ____(3)____.Themiddle covering is thin andvascularisedandiscalled____(4)____.TheinnermostcoverisaverythindelicatemembraneandiscloselystretchedovertheoutersurfaceofBrainandSpinalCordand is called _____(5)_____.

(b) Nameany5typesofnervecells.PART - II

50. Describe the structure of a dicot seed with a neat diagram.51. (a) WhatisGreenChemistry? (b) WritethefutureproductsofGreenChemistry.

PART - III52. Modernatomictheorytakesupthewaveconcept,principleofuncertaintyandother

latestdiscoveriestogiveaclearcutpictureaboutanatom.Statethefindingsofmodernatomictheory.

53. Explain the manufacturing of Ethanol from Molasses.PART - IV

54. (a) Newton’sfirstlawofmotiongivesaqualitativedefinitionofforce.Justify. (b) Thefigurerepresentstwobodiesofmasses10kgand15kg,movingwithaninitial

velocityof10ms–1 and 5 ms–1respectively.Theycollidewitheachother.Aftercollision,theymovewithvelocities4ms–1 and 9 ms–1respectively.Thetimeofcollisionis2s.NowcalculateF1 and F2.

10 kg 15 kg 10 kg 15 kg 10 kg 15 kg

10m/s 5m/s F1 F24m/s

9m/s

55. StateandexplainthedefectsofVision.Howcanthesedefectsberectified?





www.Padasalai.Net

SURA BOOKS


ANSWERS

Section - I

1. Beta 2. BCG3. Thymus 4. Micropyle5. Leftauricleandleftventricle 6. Mycorrhizalroot7. Primarytreatment 8. Helium-oxygen9. Lactic acid 10. 14th group11. Ethanoic acid 12. 0.01 mm13. force 14. electricenergy15. magneticfield

Section - II16. (i) intraspecific (ii) intergeneric17. Geneticengineeringisthemodificationofthegeneticinformationoflivingorganisms

bymanipulationofDNAbyadding,removingorrepairingpartofgeneticmaterialandchangingthephenotypeoftheorganism.

It is also known as gene manipulation or Recombinant DNA Technology (r-DNATechnology).

18.

(i) Vaccine microbes(ii) Naturalgas fuel(iii) Citric acid organic acids(iv) Vitamins metabolism

19. Symptomsof theMarasmusdiseasearenotcorrectlygivenhere.For thediseaseofKwashiorkaronly,thechilddevelopsanenlargedbellyandswellinginthefaceandfeet.IncaseofMarasmusdisease,thesymptomsarelossofweightandseverediarrhoeaanditwillappearasthoughbonesarecoveredbytheskin.

20. (i) Adrenal Gland. (ii) Adrenal Cortex.

Adrenal gland Adrenal cortex





www.Padasalai.Net

SURA BOOKS


21. (i) Exine

(ii) Tube nucleus

22. (a) Theskinofcamelisdoublythick. (b) Theskincontainswater-storingosmoticcellstoconservewater,astheylivein

deserts. (c) Theyhavethickbushyeyebrowscoveringtheeyestoprotecttheireyesfromsand

storms. (d) Their nostrils can be closedduringdesert storms to prevent the entry of sand

particles.23. (i) Glomerulus. Reason : It is a network of blood capillaries. The other three are the blood proteins

seen in plasma. (ii) Seal. Reason : The habitat of seal is Ocean. The habitats for the other three are High

mountains.24.

Excretory organ Disposed as Excretory productsKidneys Urine NitrogenouswasteproductsUrea,

Uric acid, Creatinine etc.Lungs Exhaled / Expired air Carbon dioxide and water vapourSkin Sweat Excess water and salts

25. (i) A - Geotropism B - Phototropism (ii) Themovementsingeotropismandphototropismaredependentongrowthbutin

Mimosathemovementisindependentofgrowth.26. (i) Fermentation (ii) Yeast27.

A B(a) Ammonotelic (ii) fish(b) Ureotelic (iii) mammal(c) Uricotelic (iv) birds(d) Nephridia (i) annelids





www.Padasalai.Net

SURA BOOKS


28. grass → grass hopper → frog → snake → eagle grass - producer grasshopper - primaryconsumer(Herbivores) frog - Primarycarnivores snake - Secondarycarnivores eagle - Tertiary carnivores.29. Thevariousliquidbiofuelsfortransportationare, 1. Bio alcohol 2. Green diesel 3. Bio diesel 4. Vegetable oil.30.

Sources A B CRenewable Hydrogen Wind SolarenergyNon–Renewable Coal Naturalgas Petroleum

31. Coal,Petroleum,Naturalgas.32. Thephenomenonbywhichthecolloidalparticlesareincontinuousrandommotionis

called Brownian movement.33. WeightofNaCl = 20g Weight of H2O = 50 g

Weight percent = Weight of soluteWeight of solute + Weight of solvent

× 100

= 2020+50

× 100

= 28.57%.

34. Solution :

Numberofmolesofatoms= Number of AtomsAvogadro's number

= 22

23

12.046 10 12106.023 10

× = ××

= 0.2 moles.

35. (i) Acid A is a weak acid. Acid B is a strong acid. (ii) Exampleforweakacid:CH3COOH. Exampleforstrongacid:HCl.





www.Padasalai.Net

SURA BOOKS


36. (i) HCOOH. Reason : It is Organic acid. (ii) Vinegar Reason : It is acidic in nature.37. (i) Second period is a short period. It contains eight elements.

(or) First period is the shortestperiod.Itcontainsonlytwoelements. (ii) Group 17elementsarecalledHalogenfamily.

(or) Group 18 elements are noble gases or insert gases.38. (a) Assertionandreasonarecorrectandrelevanttoeachother.39. (i) Compoundusedinpicklesasapreservativeisvinegar–Aceticacid–CH3COOH.

When Acetic acid reacts with ethanol, in the presence of conc. H2SO4, it forms ester with sweet smell.

Compound Molecular formula NameA CH3COOH Acetic acid (or) ethanoic acidB CH3COOC2H5 Ethylethanoate

(ii) The process is called Esterification.

→2 5 3 3 2 5 22 4

Ethanol Ethanoic acid Ethyl ethanoate(A) (B)

conc.H SOC H OH + CH COOH CH COOC H + H O

40. (d) (A)iscorrectand(R)supports(A).41. m = 1 kg h = 20 m Velocitywithwhichtheobjecthitstheground v2 = u2 + 2as

v2 = o2 + 2ghv = v= 2gh

v = 2gh

2×10×20 4001

= =

= −20 1ms

Velocitywithwhichtheobjectrebounds v2 = –20 ms–1

Change in momentum = Final momentum - Initial momentum = mv2–mv1 = [(1 × (–20)] – (1 × 20) = –20 – 20 = – 40 kg ms–1

\ Magnitude of change in momentum is 40 kg ms–1.





www.Padasalai.Net

SURA BOOKS


42. Components Symbols

(a) An electric cell (ii) + -

(b) Plugkey(or)switch(closed) (iv) ( )

(c) Awirejoint (i)

(d) AresistorofresistanceR (iii) 43. (i) Ammeter (ii) Non–conventionalsourceofenergy44. Oceanthermalenergy: • Oceanthermalenergyconversionusesthetemperaturedifferencebetweencooler

deep and warmer shallow or surface water. • Ingeographicalareaswithwarmsurfacewaterandcolddeepwater,thetemperature

differencecanbeleveragedtodriveasteamcyclethatturnsaturbineandproducepower.

• Warmsurfaceseawaterpassesthroughaheatexchanges,vaporisingalowboilingpointworkingfluidtodriveaturbine,generatorproducingelectricity.

45. (a)

PF

C r i

N

M

(b) Araypassingthroughtheprincipalfocusofaconcavemirror,afterreflection,willemerge parallel to the principal axis.

46. Fleming’s right hand rule:Stretchthethumb,forefingerandmiddlefingerofrighthandsothattheyaremutuallyperpendiculartoeachother.Iftheforefingerindicatesthedirectionofthemagneticfieldandthethumbshowsthedirectionofmotionofconductor,thenthemiddlefingerwillshowthedirectionofinducedcurrent.

47. (i) u = –25 cm v = +20cm f = ?





www.Padasalai.Net

SURA BOOKS


1f

= 1 1v u

−

= 120

125

−−

= 120

125

+

= 5 4100

9100

+ =

\ f = 1009

11 11= . cm

Section - II

PART - I48. (a) 1. Sanitarymeasuresincludegroundfoggingwithdisinfectants. 2. Preventwaterstagnationandcoverditchesanddrains. 3. Usemosquitonetsandrepellants. (b) Chills,shiveringandariseintemperature.

49. (a) (1) Meninges. (2) Vertebral column. (3) Duramater. (4) Arachnoid membrane. (5) Piamater. (b) Types of nerve cells: (1) MyelinatedorMedullatedorWhiteneurons. (2) Non-MyelinatedorNon-MedullatedorGreyneurons. (3) Unipolar neurons. (4) Bipolar neurons. (5) Multipolar neuron.

PART - II50. Structure of a dicot seed (bean) : Theseedisbulky,ovalandslightlyindentedononeside.Onthissidethereisa

short longitudinal, whitish ridge called the raphae. Atoneendoftheraphaethereisaminuteopeningknownasgermporeormicropyle. Ifawatersoakedseedispressedgentlyasmalldropofwateralongwithairbubbles

willbefoundcomingoutthroughthemicropyle. Theembryoisenclosedbytheseedcoat.Itconsistsofcotyledonsattachedtothe

primaryaxiswhichhasrudimentaryrootportioncalledtheradicleandarudimentarystem portion known as plumule.





www.Padasalai.Net

SURA BOOKS


Thetipoftheradicleprojectsoutside,andisnearertothemicropyle.Theplumuleisplacedbetweenthetwocotyledonsandconsistsofashootaxis,andasmallbudhavingtwotinylittlefoldedleaves.

Seed coatplumule

Radicle

Cotyledons

Dicot Seed (Bean)

51. (a) Green chemistry is the design of chemical products and processes to reduce or eliminatetheuseandgenerationofhazardoussubstances.

(b) Future Products : • Arawmaterialfeedstockshouldberenewableratherthandepleting,whenever

technicallyandeconomicallypractical. • Catalyticreagentsaresuperiortostoichiometricreagents. • GreenChemistryisapplicabletoallaspectsoftheproductlifecycleaswell. • Newleadfreesolderswithlowerheatrequirementsarebeingdeveloped.

PART - III

52. The findings of modern atomic theory are given as follows: (i) An atom is the smallest particle which takes part in chemical reactions. (ii) Anatomisconsideredtobeadivisibleparticle. (iii) Theatomsofthesameelementmaynotbesimilarinallrespects. e.g.:Isotopes[17Cl35, 17Cl37] (iv) Theatomsofdifferentelementsmaybesimilarinsomerespects. e.g.:Isobars[18Ar40, 20Ca40] (v) Theratioofatomsinamoleculemaybefixedandintegralbutmaynotbesimple.

e.g.:C12H22O11 is not a simple ratio (Sucrose) (vi) The atomsof one element canbe changed into atomsof another element by

transmutation.





www.Padasalai.Net

SURA BOOKS


(vii) Themassofanatomcanbeconvertedintoenergy.ThisisinaccordancewithEinstein’sequationE=mc2.[E=Energy,m=mass,c=speedoflight].

UsingEinstein’sequationE=mc2stabilityandreactivityoftheelementsandmoleculesarededucedusingmodernatomictheoryaswelltheusageofatomasasourceofenergyisalsoknown.

53. Manufacture of Ethanol:Molasses is dark coloured syrupy liquid left after thecrystallizationofsugarfromtheconcentratedsugarcanejuice.Molassesstillcontainsucroseandthissucroseisconvertedintoethanolbythefollowingsteps:

(i) Dilution :Molassesisfirstdilutedwithwatertobringdowntheconcentrationofsugar to about 8 to 10%.

(ii) Addition of ammonium salts :Molassesusuallycontainsenoughnitrogenousmattertoactasfoodforyeastduringfermentation.Ifthenitrogencontentofthemolasses ispoor, itmaybe fortifiedby theadditionofammoniumsulphateorammonium phosphate.

(iii) Addition of yeast : The solution from step (ii) is collected in large ‘fermentation tanks’andyeastisaddedtoit.Themixtureiskeptatabout303Kforafewdays.Duringthisperiod,theenzymesinvertaseandzymasepresentinyeast,bringabouttheconversionofsucroseintoethanol.

12 22 11 2 6 12 6 6 12 6

6 12 6 2 5 2

Sucrose Glucose Fructose

Glucose or Fructose Ethanol

invertase

zymase

C H O + H O C H O + C H O

C H O 2C H OH + 2CO

→

→ ↑

Thefermentedliquidistechnicallycalledwash. (iv) Distillation of wash : Thefermentedliquidcontaining15to18%alcoholandthe

restofwater,isnowsubjectedtofractionaldistillation.Themainfractiondrawn,isanaqueoussolutionofethanolwhichcontains95.5%ofethanoland4.5%ofwater.Thisiscalledrectifiedspirit.Themixtureisthenheatedunderrefluxoverquicklimefor about 5 to 6 hours and then allowed to stand for 12 hours. On distillation of this mixture, pure alcohol (100%) is obtained. This is called absolute alcohol.

PART - IV54. (a) Newton’sfirstlawofmotionstatesthatanobjectremainsinthestateofrestor

ofuniformmotioninastraightlineunlesscompelledtochangethatstatebyanapplied unbalanced force.

Reason : Wetendtoremainatrestwithrespecttotheseat,untilthedriverappliesbrake to stop the motor car. With the application of brake, the car slows downbutourbodytendstocontinueinthesamestateofmotionbecauseof inertia.A sudden applicationof brakemay cause injury to us bycollision with the panels in front.





www.Padasalai.Net

SURA BOOKS


(b) 10 kg 15 kg 10 kg 15 kg 10 kg 15 kg

10 m/s 5 m/s F1 F24 m/s

9 m/s

A B A B A B

MassofabodyA,(m1) = 10 kg MassofabodyB,(m2) = 15kg InitialvelocityofA,(u1) = 10 m/s InitialvelocityofB,(u2) = 5 m/s FinalvelocityofA,(v1) = 4 m/s FinalvelocityofB,(v2) = 9 m/s The time of collision, (t) = 2 seconds. AccordingtoNewton’ssecondlawofmotion, Force acting on B (action), F1 = mass of B × acceleration on B

F1 = m v ut

2 2 2( )−

= 15 9 52

15 42

30( )−

= × = N

F1 = 30N

Force acting on A (reaction), F2 = mass of A × acceleration on A

F2 = m v ut

1 1 1( )−

= 10 4 102

10 62

30( ) ( )−

=× −

= − N

F2 = –30N

AccordingtoNewton’sthirdlawofmotion F1 = –F2

\ F1 = 30N F2 = –30N





www.Padasalai.Net

SURA BOOKS


55. Defects of vision :Therearethreecommonrefractivedefectsofvision. (1) Myopia or near-sightedness : Apersonwithmyopiacanseenearbyobjectsclearly

butcannotseethedistantobjectsdistinctly. Theimageofadistantobjectisformedinfrontoftheretinaandnotattheretina

itself.

(a) Far point of myopia eye (b) Myopia eye

(c) Correction of myopia eye

(2) Hypermetropia or far-sightedness : Apersonwithhypermetropiacanseedistantobjectsclearlybutcannotseenearbyobjectsdistinctly.

Thisisbecausethelightraysfromaclosebyobjectarefocussedatapointbehindthe retina.

(a) Near point of hypermetropic eye (b) Hypermetropia eye

(c) Correction of hypermetropia eye

(3) Presbyopia : Thepowerofaccomodationoftheeyeusuallydecreaseswithageing.Theyfind it difficult to see near by objects confortably anddistinctlywithoutcorrectiveeye-glasses.Thisdefectiscalledpresbyopia.

Defects be rectified : (i) Myopia :Thisdefectcanbecorrectedbyusingaconcavelensofsuitablepower. (ii) Hypermetropia : Thisdefectcanbecorrectedbyusingaconvexlensofappropriate

power. (iii) Presbyopia :Suchdefectsarerectifiedusingby-focallenses.Acommontypeof

by-focal lensesconsistsofbothconcaveandconvex lenses.Theupperportionconsistsofaconcavelens.Itfacilitatesdistantvision.Thesedays,itispossibletocorrecttherefractivedefectslikePresbyopiawithcontactlenses.





www.Padasalai.Net

SECTION - I (MARKS : 15) · PDF fileSURA BOOKS MARCH - 2017. Public Exam Question Paper with Answers [Time Allowed : 2.30 Hours] SCIENCE [Maximum Marks : 75] SECTION - I (MARKS : 15)

Documents