BECE Past Questions & Answers – 1994 (SCIENCE)

August 1994

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) Distinguish between thefollowingterms:
(i) Physical change andchemical change
(ii) Solution and suspension

(b) Classifythe followingaseither aphysical or chemical change
(i) Common saltin water
(ii) (iii) (iv) Burningofcharcoal
Meltingof ice
Hydrochloricacid in sodium hydroxide solution

(d) Givethe chemical symbols of the followingelements
(i) (ii) (iii) (iv) Oxygen Chlorine Aluminium Calcium

(e)
(i) (ii) (iii)
Explain the term self-pollination
Name four agents of pollination
Statethe function ofthebrightlycoloured petals in insect pollination

2. (a) (i) Explain the term digestion
(ii) Statethe end products ofdigestion ofeach of thefollowingfood substances
(α) carbohydrates;
(β) proteins;
(γ) fats and oils
(iii) Name the enzyme present in saliva and state its function

(b) (i) Bywhat process does theheat of thesun reach theearth?
(ii) An aluminium bowl placed on a tableis filled with hot water. Name theprocesses by
which heat is lost bythebowl.
(iii) Giveone reason whywood is used as a handleforsome cookingutensils.

(d) (i) What are alloys?
(ii) Givetwo examples of alloys andstatetheir constituents

3. (a) (i) Explain the term friction
(ii) Givetwo methods of reducingfriction
(iii) A rigid bar is used to lift a stone
(α) Drawadiagram showing the effort, pivot and loadpositions
(β) Ifthe length of the bar is100 cm and thepivotis placed 80 cm from the effort,
calculate theload distance

(b) (i) Explain the term excretion
(ii) Statethe organs in human beings which excrete the following waste products:
(α) Sweat
(β) Carbondioxide
(γ) Urine

(c) (i) What is a food chain?
(ii) Drawa food chain using the followingorganisms:
Hawk, cassavaleaf, lizard and grasshopper

(d) Statethree conditions necessaryforthegermination ofseed.

(e) (i) Name two diseases which can betransmitted sexually
(ii) Givetwo features whichcan bepassed on from parents to children

4. (a) (i) Listthe various planets of the solarsystem in theorder theyoccurstarting with theplanet nearest thesun

(ii) Stateonedifferencebetween the eclipse of thesunand the eclipse of themoon.

(b) (i) Definethe term force
(ii) Statethreetypes offorce
(iii) A boxis pulled byaforceof 20N through adistanceof 8m alongasmooth floor.
Calculate theworkdonebythe force.

(c) Draw simple electricalcircuits showingthefollowingarrangements: (i) A switch and alight bulb in series with two drycells in series (ii) A switch and alight bulb in series with two drycells in parallel

(d) Name two diseases that can be controlled byimmunization CLICK TO VIEW ANSWERS TO PART 2

August 1994

SCIENCESectionB

SOLUTIONS

ESSAY

1. (a) Difference
(i)

Physical change Chemical change
No new substanceis formed A new substanceis formed
It is usuallyreversible It is irreversible (notreversible)

(ii)

Solution Suspension
A liquid/fluid which has oneor
moreothersubstances uniformlydissolved in it
adispersion of fine solid particles in a liquid orgas

(b) (i) Commonsalt in water – Physical change
(ii) Burning ofcharcoal – chemical change
(iii) Melting ofice – Physical change
(iv) HCl inNaOH – chemical change

(ii) Examples:
PARASITE

HOST
Tapeworm human / mammal
Tick dog/ cattle / sheep
Dodder milk bush / alfalfa /clover
Broomrape tomato crop
Mistletoe apple / oak trees
Witch weed sugarcane/ corn
Plasmodium human

Roundworm human/ mammal Hookworm human/ mammal Guineaworm human/ mammal Schistosome human/ mammal [anytwo]

(d) ELEMENT CHEMICAL SYMBOLS (i) Oxygen – O
(ii) Chlorine – Cl (iii) Aluminium – Al (iv) Calcium – Ca

(e) (i) Self-pollination
Thetransfer ofpollengrains from an antherof aflower to thestigmaof thesame flower.

(ii) Agents ofpollination
Wind, water, insects, birds, man,

(iii) Function of brightly coloured petals
To attract insectsand birds

2. (a) (i) Digestion
Thebreakdown of food in the bodyinto simpler forms that can beabsorbedinto the bloodstreamand used

(ii) ENDPRODUCTSOF DIGESTION
(α) carbohydrates – glucose
(β) proteins – amino acids
(γ) fats andoils – fattyacidsandglycerol

(iii) Enzymeinsaliva andits function
Ptyalin – break down starch into sugar

(b) (i) process by which heatofthesunreachthe earth
Radiation

(ii) Conduction and convection

(iii) Wood is abad conductorof heat, henceheat fromthe cookingutensildoes not easilyget to thehand.

(c)

Vegetative parts Reproductiveparts
stem
roots leaves
flowers (stigma, style, ovary, anther&filament)

(d) (i) Alloys
Substance containingtwo or moremetalsphysicallyanduniformlycombined
Or: A homogeneous mixtureof two or moremetals

(ii) ALLOY CONSTITUENTS
Steel Bronze Brass Duralumin iron and carbon copper and tin copper and zinc
Aluminium, copper andmanganese

3. (a) (i) Friction
The forcethat opposes the relative slidingmotion of two bodies in contact
Or:
The resistance encountered byan object movingrelative to anotherobjectwith which it is
in contact

(ii) Methods ofreducing friction
 Applyinglubricants suchas grease/ oil
 Smootheningthe contact surfaces
 Usingwheels /rollers
 Usingballbearings

(iii)

(α) Diagramshowingeffort,pivotand load positions

(β) Load distance= total length– effort distance
= 100 cm– 80 cm
= 20 cm

(b) (i) Excretion
The removal ofmetabolic waste materials from the cells of abody
Or:
Thedischargeof wastematter from the body’s tissues ororgans

(ii) EXCRETORY ORGAN
(α) Sweat Skin
(β) Carbon dioxide Lung
(γ) Urine Kidney

(c)
(i)
Foodchain
Thelinear sequencethatshows energytransfer from one livingorganismtothe other by
feedingor being fed upon
Or
A hierarchyof different livingthings, each of which feeds on theonebelow to obtain
energy

(ii)
Foodchain
Cassavaleaf →grasshopper →lizard →hawk

(d) Conditions necessary forgerminationofseed
Viable seed, suitabletemperature, air, moisture/water
[anythree]

(e) (i) Diseases that can be transmittedsexually
 AcquiredImmuneDeficiencySyndrom (AIDS)
 Gonorrhea
 Genital warts
 Syphilis
 Hepatitis B
 Genital herpes
[anytwo]

(ii) Features thatcan bepassed fromparents tochildren
 Intelligence
 Height,
 Colour ofeyes,
 Shape/sizeof nose/ear/mouth,
 Colour ofskin,
 Abilityto roll tongue [anytwo]

4. (a) (i) Planets ofthesolarsysteminorder
Mercury,Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, (Pluto)

(ii)

Eclipse ofthesun Eclipseofthemoon
Themoon comes between the
earth and the sun The earth comes betweenthe
moon and thesun
Theshadow ofthemoon is
cast on the earth Theshadow ofthe earth is cast
on the moon
[anyone]

(b) (i) Force
A forceis a push or pullexerted on abody.
Or:
A physical influencethattends to changethe position or shapeofan objectwith mass

(ii)
Types offorce
Gravitational, tensional,centripetal, centrifugal,magnetic, electrostatic, upthrust, cohesive, adhesive
[anythree]

(iii)

Work done = force × distance
= 20 N × 8 m
= 160 Nm or 160 J

(ii) A switchanda light bulbinseries with two drycells in parallel

(d) Diseasesthatcanbecontrolledbyimmunization
Smallpox,Measles,Chickenpox,Whoopingcough,Tetanus,Poliomyelitis,Tuberculosis, Diphtheria
[anytwo]

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