Home / Science / BECE Past Questions & Answers – 1991 (SCIENCE)

BECE Past Questions & Answers – 1991 (SCIENCE)

August 1991

SCIENCE

SECTIONB ESSAY
1 hour [60 marks]

Answerthreequestionsonlyfrom this section.
Illustrate your answers wherever possible, with large, clear and fully labelled diagrams. Creditwill be given for clarity of expression and orderlypresentation ofmaterial.
All questions carry equal marks

1. (a) (i) What is the differencebetweenself-pollination and cross-pollination?
(ii) Name two agents of cross-pollination.

(b) A rayof light strikes thesurfaceof aplanemirrorat an oblique angle.
Drawa raydiagram to show each of the following: (i) the normal
(ii) the incident ray
(iii) the reflected ray
(iv) the angle ofincidence
(v) the angle ofreflection

(d) (i) Carbondioxide is prepared in thelaboratorybypouringsomedilute hydrochloric acid on
calcium carbonate. Giveabalanced equation for this reaction.
(ii) Howwouldyou test forcarbondioxide?
(iii) Giveoneuse ofcarbondioxide.

(b) Mention threeways of protectingpeople from infection duringan outbreakof cholera.

(d) Listthe names of theplanets in order oftheirdistances awayfrom the sun; startingwith theone nearest to it.

3. (a) (i) What is a solution?
(ii) Write down balancedchemical equations forthe preparation ofthe followingsubstances.
(α) SodiumChloride: Preparedfrom a reaction between Sodiumhydroxide and
dilute hydrochloricacid
(β) Ammonia: Preparedfrom a reaction between nitrogenand hydrogen.

(b) Classifythe followingunder voluntaryand involuntaryactions:
(i) Laughing
(ii) (iii) (iv) Blinkingof theeyes
Sneezing
Eating

(c)
(i) (ii)
State four characteristicswhich are common to all livingthings. Write down one functionof each of the following:
(α) Leaves
(β) Roots

(d)
(i) (ii)
Mention two main defects of thehuman eye. How arethesedefectscorrected in each case?

4. (a) (i) Name thegaswhich is used in both rustingand burning.
(ii) Statetwo ways in whichrustingcan bepreventedin everydaylife.

(b) Classifyeach of thefollowingitems as element, compound,mixtureor colloid: (i) Sodiumchloride
(ii) Sugar solution
(iii) Fog
(iv) Hydrogen
(v) Sulphur

(ii)
Name two diseases that can be controlledbyimmunization.

(d)
(i)

(ii)
A boythrows astone verticallyup into the air. What aretheenergychanges that take place as the stone falls tothe ground?
Givetwo appliances which use electromagnets intheiroperation
(iii) Listtwo ways in whichamagnet can lose its magnetism. CLICK TO VIEW ANSWERS TO PART 2

August 1991

SCIENCESectionB

SOLUTIONS

ESSAY

1. (a) (i)

Self-pollination
Cross-pollination

Thetransfer ofpollengrains from an antherofa flower to thestigma ofthe same flower. Thetransfer ofpollengrains from the
antherofa flower to thestigma of another flower on another plant of the same kind.

(ii) Agents ofcross-pollination
Wind, water, insects, birds, man [anytwo]

(b) Ray diagramshowing

(c) Properties ofimageformedby planemirror
 Same size as object
 Same distance from mirror as object
 Virtual
 Erect /upright
 Laterallyinverted [anyone]

(d) (i) Balancedequationfor reaction
CaCO3+2HCl → CaCl2+H2O +CO2

(ii) Test for carbon dioxide
Pass the carbondioxidethrough lime water[Ca(OH)2]; Thelime waterturns milky.

(iii) Uses ofcarbon dioxide
 Fire extinguisher
 Photosynthesisin greenplants
 Refrigerant
 Production ofsoft drinks
 Oneof thegases used inanaesthesia
[anyone]

2. (a) (i) Excretion
Theremoval ofmetabolic waste materials from the cells of abody
Or:
Thedischargeof wastematter from the body’s tissues ororgans

(ii)
Respiration
Thebreakdown of food substances in an organismto releaseenergy,carbon dioxide,
water

(iii)
Organ responsible for
Excretion: lung, skin, kidney [anyone] Respiration: lung

(b) Ways ofprotecting people frominfection during anoutbreakofcholera
Ensuring that(people)
• Receive immunization
• Eat hot meals,
• drink clean potablewater,
• wash hands with soap after visitingthe toilet
• cover meals to prevent flies from settlingon them
• keep the environment clean and freefrom filth
[anythree]

(c) CHEMICAL NAMES
(i) (ii) MgCl2
FeS Magnesiumchloride
Iron (II)sulphide
(iii) (iv) CuSO4
NH4OH Copper (II)sulphate
Ammonium hydroxide

(d) Theplanets inorder:
Mercury,Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto)

3. (a) (i) Solution
A liquid which has oneor moreothersubstances uniformlydissolved in it.

Or:
A fluid consistingof twoor moresubstances mixed together and uniformlydispersed

(ii) Balancedchemicalequation for:
(α) SodiumChloride: Prepared froma reaction between Sodiumhydroxide
and dilutehydrochloricacid
NaOH +HCl → NaCl + H2O

(β) Ammonia: Prepared froma reaction between nitrogenand hydrogen
N2+3H2 → 2NH3

(b)

VOLUNTARY INVOLUNTARY
Laughing blinkingof theeyes
eating sneezing

(c) (i) Characteristics commonto allliving things
 Theyrespire
 Theyexcrete
 Theyfeed
 Theygrow
 Theyreproduce
 Theyrespond / aresensitive to stimuli
[anyfour]

(ii) Function of:
(α) Leaves
 Photosynthesis(preparation of food using carbondioxide and water)
 Transpiration (loss of watervapourthrough the stomata)
 Respiration (intakeof oxygen to produceenergy)
 Guttation (oozingout of excess waterfrom the surfaceof leaf)
 Food storageincertain leaves

(β) Roots [anyone]

 Absorbs waterand mineral saltsfrom the soil
 Some roots store food prepared bytheplant
 Holds the plant firmlyinplace

(d) (i) Main defects ofthehumaneye [anyone]

 Longsightedness(seeing from longdistances only/ notseeingfrom a closedistance)
 Short sightedness (seeingfrom short distances only/ notseeingfromalongdistance)

(ii) Correction oflong sightedness
Convex/ converginglens areusedto correct long sightedness

Correction ofshort sightedness
Concave/ diverginglensareusedtocorrect short-sightedness

4.
(a)
(i)
Gas usedin bothrusting andburning
Oxygen

(ii)
Ways ofpreventing rusting
 Painting
 Greasing/ oiling
 Galvanizing

(b) Classify as element, compound, mixtureor colloid
(i) Sodiumchloride – compound
(ii) Sugar solution – mixture
(iii) Fog – colloid
(iv) Hydrogen – element
(v) Sulphur – element

(c) (i) foodchain
Greengrass→grasshopper →bird
Or: Greengrass→goat →Man
Or: grasshopper →bird →Man
(ii) Disease that can be controlled by immunization
Smallpox, Measles, Chicken pox, Whoopingcough, Tetanus, Poliomyelitis, Tuberculosis, Diphtheria

(d) (i) Energy changes– stone falling to theground
Potential →Kinetic→Sound +Heat
(ii) Appliances that use electromagnets
Speakers, motors, computerhard drives,microphones, telephonereceivers,electricbells

(iii) Ways by whicha magnet canlose itsmagnetism
– Byheatingitaboveacertain temperature(knownas the Curietemperature)
– Byplacingitin a magnetic field ofopposite polarity; eitherfrom another permanent magnet or asolenoid
– Byaphysical shock; through droppingitor hitting it with ahammer
[anytwo]

Pages: Page 1, Page 2