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BECE Past Questions & Answers – 2006 (SCIENCE)

April2006

SECTION B

1 hour15 minutes

ESSAY [75marks]

This section is in two parts, I and II

AnswerQuestion1ofPartIand any other three questions in Part II.

Credit will be given for clarity of expression and orderly presentation of material

PART I
[30 marks]

(Compulsory– Answer all of Question 1)

1. (a) The diagram below shows the electrical method of magnetizing a nail.

Study the diagram and use it to answer the questions that follow.

(i) Give the names of the parts of the circuit labelled I,II and III (ii) List two substances that can be made into a magnet.
(iii) State two other methods of making magnets.
(iv) Name one material that is used in making an electrical wire
(v) Give two properties of the material you named in (iv) which makes it useful as a wire.
[10 marks]

(b) The diagram below shows the set-up for the preparation of carbon dioxide in the laboratory.

(i)

(ii) Name the parts of the set-up labelled I and II

Give the name of the method of gas collection shown in the diagram.
(iii)

(iv) Give one property of gases collected over water

What will happen if component I does not dip into the contents of the flask?
(v)

(vi) List two compounds that form the content of the flask.

Write down the systematic name of carbondioxide. [10 marks]

(c)

In an experiment,yam pap is put into two test tubes A and B containing iodine solution.

The test tubes are warmed slightly to a temperature of 37°C and saliva is put into test tube B

(i) State the colour of the content of test tube A

(ii) State the colour changes of the contents in test tube B after about 3 minutes.

(iii) Fehling’s solution is added to the contents of test tube B after the3 minutes and it turns brick- red. What food substance is present?
(iv) Give two functions of saliva in eating.

(v) Why was it necessary to warm the contents of the test tubes to about 37°C?

(vi) Give two aims of the experiment. [10 marks]

PART II
[45 marks]

(Answer three questions only from this part)

(a)

(i)

State two conditions that are required for photosynthesis to take place.
(ii) How would you show that starch is formed during photosynthesis?

(b) Write a balanced chemical equation to show the reaction between hydrogen and oxygen.

(ii)
Give one example of a natural satellite.

(iii)
List two uses of artificial satellites.

3. (a) Define
(i) self-pollination
(ii) cross-pollination

(b)
State two ways in which cross-pollinated plants are better than self-pollinated plants.

(i) Write a balanced equation for the reaction

(ii) What is the name given to this reaction?

(d)
Describe an experiment to show that pressure acts in all directions in a liquid

4. (a) (i) What is a vector of a disease
(ii) State two methods each by which the vectors of the following diseases can be destroyed:
α) river blindness;

β) malaria

(b) Write down the systematic names of the following compounds:

(i) (ii) CaCO3
FeS
(iii) (iv) NaCl
NaOH

(ii)
In an experiment to determine density, a stone of mass 60 g is put into a bowl containing water
If the level of the water rises from the60 cm3mark to 75 cm3, determine the density of the stone.

5. (a)

(b) Mention five differences between plants and animals

Define each of the following terms,giving one example in each case
(i) (ii) compound element

(ii)
Draw and label a simple electrical circuit made up of a cell and a switch connected to two electrical bulbs connected in parallel CLICK TO VIEW ANSWERS TO PART 2

April 2006

SCIENCE Section B

SOLUTIONS

ESSAY

1. (a) (i) I – Cell

II – Key or switch

III – Solenoid or coil

(ii) Substances: Iron (Fe), Steel, Nickel (Ni), Cobalt(Co) [any two]

(iii) Methods of making magnets
• Single stroking
• Double stroking
• Induction
• Hammering [any two]

(iv) Material for electrical wire:

Copper (Cu), aluminum (Al), steel, iron (Fe),gold(Au), silver (Ag), and platinum (Pt) [anyone] (v) Property of material
 ductile,
 malleable,
 low resistivity
 high tensile strength [any two]

(b) (i) I – thistle funnel
II – delivery tube

(ii) Upward delivery or down ward displacement of water

(iii) They are

• insoluble in water;
• less dense than water [anyone]

(iv) The gas produced will escape through the thistle funnel

(v) Content of flask
• Calcium carbonate [CaCO3] – (reactant)
• Hydrochloric acid [HCl] – (reactant)
•
• Calcium chloride
Water [CaCl2] [H2O] – (product)
– (product)

(vi) Carbon(IV) oxide

(ii)
pale blue black

(iii)
maltose or reducing sugar

(iv)
Functions of saliva
 makes the food softer for easier chewing and swallowing
 Contains the enzyme ptyalin, which breaks down carbohydrates to reducing sugar

(v) To attain thenormal bodytemperature, at which the enzyme in salivacanwork efficiently

(vi) Aims ofexperiment
 To show that saliva contains enzymes that digest carbohydratesorstarch
 To show that digestion ofcarbohydrates starts in themouth, wheresalivais produced
 To show thatyamcontains starch

2. (a) (i) Thepresenceof water, carbondioxide, chlorophylland light

(ii)
Experiment
 Pluck aleaf from aliving plantthat has been in sunlight for3 ormorehours.
 Boilthe leaf to kill the cells andstop the process of photosynthesis
 Placethe leaf in warmalcohol forsomeminutes to remove the chlorophyll
 Placethe leaf in warm waterto washawaythealcohol and softenthe leaf
 Placeafew drops of iodinesolution on the leaf

Observation andConclusion
It is observed that the leaf turns blue-black. Thiscolouration indicates thepresenceof starch. This show that starch is formed duringphotosynthesis

(b) H2 + O2 → 2H2O

(c)
(i) (ii)
A satellite is anyheavenlybodythat orbits (revolves around)alarger one. Themoon is a natural satelliteof the earth;
Theplanets arenatural satellites ofthe sun

(iii) Us
 es ofartificial satellites
Weatherstudies and forecasting
 Telecommunication
 SendingandreceivingTV signals
 Takingphotographs fromspace for various purposes
 Internet networking
 Global PositioningSystem (GPS)-aworldwide navigation system

3. (a) (i) Self-pollinationis
Thetransfer ofpollengrains from an antherof aflower to thestigmaof thesame flower

(ii) Cross-pollinationis
Thetransfer ofpollengrains from the antherofa flower to thestigmaof another flower on anotherplant ofthe samekind

(b) Produceoffspringthat aremoreresistant to diseases

Produceoffspringthat arestronger andhealthierthan parents

Causes geneticvariations in offspringthat makethem betterthen parents [anytwo]

(ii)
Neutralization reaction

(d) Experiment

Get a suitable container and makeholes of equal sizes at thesameheight around it(as shown in thediagram above

Pour water (or other liquid)into the container to fillit

Thewater (orliquid) comes out through the holes in alldirections and with thesamepressure

This shows that pressureacts in alldirections in aliquid

4. (a) (i) A vectoris
an agent that carriesandspreads organisms that cause diseasefrom infected organisms to non-infected ones.

(α) riverblindness

 Killingthe vector, theblack fly, byspraying chemicals onto the riverbanks or wherever theyarelocated

 Destroyingthebreeding grounds of theblackflybyclearingthe bushes alongthe banks of riverswheretheyarefound.

(β) malaria

 Killingthe mosquito byspraying appropriate insecticide at places wheretheyare located
 Killingthe mosquitoes byspraying room with insecticide.
 Destroyingthebreeding grounds of mosquitoes byclearingchokedgutters
 Destroyingthehidingplaces of mosquitoes byclearingbushes
 Killingthe larvaeof mosquitoes bypouringoilonthe surfaceof stagnant water
 Killingmosquitoes byusinginsecticide treated mosquito nets
 Killingmosquito larvaein ponds bystockingwithfish that feed on the larvae.

(b) (i) Calcium trioxocarbonate (IV)

(ii)
Iron (II)sulphide

(iii)
SodiumChloride

(iv)
Sodiumhydroxide

 Matter has mass

 Matter has volume (occupyspace)

(d) Density = mass ÷ volume

Mass ofstone = 60kg

Volume ofstone
= 75cm3– 60cm3

= 15cm3

Density
= 60 g÷15 cm3

= 4 g/cm3
or 4 gcm-3

(a) Differences

PLANTS ANIMALS
Manufacturetheirownfood (photosynthesis) Do not manufacturetheirown food
Cannot move freelyfromplaceto place Ableto move freelyfromplaceto place
Mostplants do not respond quicklyto stimuli Respond quicklyto stimuli
Haveacellwall Do not haveacellwall
Have chloroplasts, whichcontain chlorophyll Do not have chloroplast
Excess carbohydratesarestored as starch Excess carbohydrates arestored asglycogen
Absorb carbondioxide forphotosynthesis and

releaseoxygen aswasteproduct Inhale oxygenforrespiration and release carbon

dioxide as waste product
Cells havelargeand permanent vacuoles Cells havesmall temporaryvacuoles
Growth takes place at specific parts Growth takes place atallparts
[any five]

(b) (i) A compound is a substance formed bythe chemical combination of two ormore elements in definite proportions

Example, HCl, orNacl, orCa(OH)2, or CaCl2, or NH3,orMgCO3, etc

(ii) An element is a substancethat is madeup ofonlyonekind of atoms.

Example are: Calcium, or Sodium, orMagnesium, or Argon, or Sulphur, etc

ElectricalInsulator Electrical Conductor
Does not conduct electricity Conducts electricity
There arenofree electrons to conduct
electricity There are free electronswhich make
electrical conduction possible
Narrowconduction energyband Wide conduction energyband
Wide forbidden gap between valence
and conduction band No forbiddengap between valenceand
conduction band

(ii) simple electrical circuit

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