BECE Past Questions & Answers – 2004 (SCIENCE)

SCIENCE Section B

SOLUTIONS

ESSAY

1. (a) (i) I – Cell
II – key/ switch
III – Ammeter
IV – Electric bulb
V – Variable resistor
VI – Voltmeter

(ii) The key/switch

(iii)
The bulb will light,the ammeter will deflect, the volt meter will deflect

(iv) Chemical→Electrical→light (and heat)

(v)
Parallel connection

(b) (i) (ii) Distillation

Liquid Y – Alcohol

This is because it is more volatile and has a lower boiling point than water.Therefore,it boils
first,leaving the water behind.

(iii)
The thermometer measures the temperature within the flask

The water jacket X cools the gaseous alcohol to condense it back to liquid form

(iv)
Heating and cooling/vapourisation and condensation

(v)
Boiling points of water and alcohol which are clearly different.

(c) (i) A – Starch or carbohydrate
B – fats and oils
C – reducing sugar or simple sugar

(ii) Products of digestion

A B C – glucose
– fatty acids and glycerol
– glucose

(iii)
A B C
– Mouth
– The duodenum(first part of the small intestines)
– Mouth

(iv) C is absorbed after digestion in -The ileum(third & last part of the small intestines

2. (a) (i) Four parts of a plant used for a sexual reproduction
Rhizome, bulb, sucker,stem cutting, tuber, corm, bud [any four]

(ii) Two Advantages of sexual reproduction over a sexual reproduction
 Offspring are usually more resistant to diseases
 Offspring are usually more stronger and healthier
 Offspring have different and usually better characteristics from parents
[anytwo]

(b) (i) Why atoms are electrically neutral
The numbers of protons and electrons are equal.The positively charged protons neutralize
the negatively charged electrons, hence, making the atom electrically neutral

(ii)
Systematic names of:

(α) CuO – Copper(II)Oxide
(β) SO2 – Sulphur (IV)oxide

(c) (i) Dispersion of light
The separation of light into different wave lengths or its component colours when it passes through a given medium

(ii)
Labeled diagram showing dispersion of light through a triangular glass prism

3. (a) (i) Soil erosion

The washing away of the top soil by agents of erosion
Or:
The removal of soil material by natural processes,principally running water, glaciers, waves, andwind

(ii) Two types of soil erosion

Sheet, Gully, Rill, Splash [any two]

(b) (i) Zinc and oxygen
Name: Zinc oxide
Chemical formula: (ZnO)

(ii) Calcium and Chlorine
Name: Calcium chloride
Chemical formula: CaCl2

(c) (i)

Heat Temperature
The energy possessed by a body that
results in its hotness or coldness A measure of the hotness or coldness
of the body

Unit = joule (J) Unit = kelvin (K) or
degee Celsius (°C) or degree Fahrenheit(°F)

(ii) Labeled diagram of mercury-in-glass thermometer

(iii) Mode of heat transfer = Conduction

4. (a) (i) Hormone
A chemical secreted by an endocrine gland or some nerve cells that regulates the function of a specific tissue or organ

(ii)

Name of hormone Organ secreting hormone
Function of hormone

Adrenalin

Adrenal gland increases the speed and
force of the heart beat or
increases the energy of
the body.

Thyroxin

thyroid gland stimulates metabolism
for normal growth and development of the body

Insulin
Pancreas regulates the glucose
(sugar)level in blood

(b) (i) Balanced equation for the laboratory preparation of ammonia
NH4Cl + Ca(OH)2 → NH3 + CaCl2+ H2O
(ii) Test for ammonia gas
Hydrochloric acid is introduced into the gas. White fumes are produced in the presence of the
HCl.
Or: Gas is smelled. Ammonia has a very pungent/choky smell.

(iii) Uses of ammonia
 As a refrigerant(used in refrigerators)
 Preparation of fertilizers
 Flying of balloons
 Preparation of medicines/drugs
 Preparation of explosives [anyone]

(c) (i) Types of forces
Frictional, tensional, gravitational, centripetal, centrifugal, magnetic,upthrust
[any four]

(ii) Forces involved
 Tensional force(in the stretched catapult);
 frictional force(bird perched on the tree)
 gravitational force (bird falling to the ground); [any two]

5. (a) (i) Differences

Rhizome Stem tuber

Grows horizontally below the ground Grows vertically/diagonally below the
ground
Buds are covered by scaly leaves Buds are not covered by scaly leaves
Both nodes and inter nodes present Only nodes present

(ii) Examples of
Rhizome: Ginger, canna lily
Stem Tuber: Potato, yam

(b) Method of separation and explanation
(i) Salt and water – Evaporation
The temperatures at which water and salt evaporate are wide apart. Therefore, as the mixture is heated, the water evaporates, leaving the salt crystals behind

(ii)

(iii) Saw dust and iron filings – Magnetization
Their on filings is a magnetic substance, while saw dust is not.Hence, the magnet would attract their on filings, leaving the saw dust behind

powdered charcoal and water-Decantation or filtration
Powdered charcoal particles are insoluble in water;therefore they can be separated from water by
filtration or decantation, if the particles have settled at the bottom

(c)
(i)
Density of a substance
The mass perunit volume of the substance
Or: Density = mass /volume

(ii)
Explanation
When the volume of a body increases at a constant mass, its density reduces.Therefore,the
volume of the body is increased by increasing its hollowness/expanse such that its resultant
density is less than that of water.Then the body will float on water.