Kuulchat - WASSCE June 2020 science

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OBJECTIVE TEST

Ozone layer depletion results in

melting of ice at the poles.

increase in number of storms.

skin cancer in humans.

loss of productive farmland.

Which of the following factors can affect the boiling and freezing points of water?

Surface tension

Adhesive forces

Impurities

Density

Purple-leaf colouration in plants is a symptom of deficiency in

magnesium.

nitrogen.

phosphorus.

potassium.

Which of the following diseases in humans is caused by bacteria?

Hepatis B

Herpes

Chlamydia

Prostate

Hepatitis B is an infection of the liver caused by the hepatitis B virus. The infection can be acute (short and severe) or chronic (long term). Hepatitis B can cause a chronic infection and puts people at high risk of death from cirrhosis and liver cancer.

Herpes is a common virus that causes sores on your genitals and/or mouth. Herpes can be annoying and painful, but it usually doesn’t lead to serious health problems.

Herpes is spread from skin-to-skin contact with infected areas, often during vaginal sex, oral sex, anal sex, and kissing. Herpes causes outbreaks of itchy, painful blisters or sores that come and go.

Herpes is caused by two different but similar viruses: herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). Both kinds can make sores pop up on and around your vulva, vagina, cervix, anus, penis, scrotum, butt, inner thighs, lips, mouth, throat, and rarely, your eyes.

Chlamydia is a bacterial infection. The bacteria are usually spread through sex or contact with infected genital fluids (semen or vaginal fluid). You can get chlamydia through: unprotected vaginal, anal or oral sex. sharing sex toys that are not washed or covered with a new condom each time they're used.

Symptoms of chlamydia

Many people with chlamydia have no symptoms or only mild symptoms. If symptoms occur, they may not appear until up to three weeks after having sex with someone who has chlamydia.

In women, common symptoms include:
1. a change in vaginal discharge
2. bleeding between menstrual periods or after sex
3. pain or discomfort in the lower abdomen
4. burning sensation when urinating

Common symptoms in men include:
1. burning when urinating
2. discharge from the penis
3. pain or discomfort in the testicles

Anal infection in women and men can cause:
1. pain
2. discharge
3. bleeding

Chlamydia can also infect the throat often without symptoms.

Infants born to mothers with chlamydia may experience eye infections or pneumonia. These can be treated with antibiotic medications for newborns.

The prostate gland is a male reproductive organ that produces fluids that feed and protect sperm cells.

The three most common forms of prostate disease are:
1. inflammation (prostatitis)
2. non-cancerous enlargement (BPH)
3. prostate cancer

The part of the human ear responsible for amplification of sound is

cochlea.

ossicles.

sacculus.

utriculus.

The general formula of alkyne is

C_nH_2n+2

C_nH_2n

C_nH_2n-2

C_nH_n

Which of the following bones is present in the forelimb of man?

Femur

Radius

Ribs

Sternum

Minerals included in the layer ration for egg shell formation are calcium and

magnesium.

nitrogen.

phosphorus.

potassium.

Carrot is a good source of which of the following vitamins?

Vitamin A

Vitamin B complex

Vitamin C

Vitamin D

10.

The major reason why relative atomic mass of some elements is not a whole number is the existence of

isomerism.

allotropy.

isotopy.

isotonism.

11.

Which energy transformation occurs in a light emitting diode?

Light energy to chemical energy

Chemical energy to heat energy

Electrical energy to heat energy

Electrical energy to light energy

12.

Which of the following characteristics are associated with local breeds of fowl?

I. Resistant to diseases
II. High foraging ability
III. Susceptible to adverse weather conditions

I and II only

I and III only

I, II and III

13.

Temporary hardness of water is removed by heating because

it is caused by insoluble salts.

the salts causing the hardness become soluble.

calcium hydrogen trioxocarbonate (IV) in water is decomposed by heat.

calcium trioxocarbonate (IV) is produced.

14.

Examples of continuous variation include:

I. weight,
II. rhesus factor,
III. sickle cell.

I only

I and II only

I and III only

II and III only

15.

The number of protons in an ion with a charge of +3 is 13. How many electrons are present in the neutral atom?

16.

Metals are normally used as electrical wires because they are

brittle.

ductile.

elastic.

malleable.

17.

One advantage of male circumcision is that, it

allows for easy penetration in the vagina.

keeps the penis free from germs.

makes the man sexually active.

makes the man sexually inactive.

18.

Organic manures are preferred to inorganic manures because, they are

easy to apply.

readily available to plants.

relatively cheap.

toxic to plants.

19.

Calculate the number of moles in 5.85 of NaCl.

[Na = 23; Cl = 35.5]

0.01

0.10

1.00

10.00

Mole Formula

Mole = $\frac{Mass}{Molar Mass}$

Mass = 5.85

Na = 23
Cl = 35.5

Molar mass = 23 + 35.5 = 58.5

Mole = $\frac{5.85}{58.5}$ = 0.10

20.

The diagram below illustrates a ray of light incident on a plane mirror MM^'.

The value of α is

40°

50°

80°

100°

21.

A respiratory surface must have

I. rich supply of blood capillaries.
II. thin wall.
III. large surface area.

Which of the statements above is/are correct?

I only

I and II only

II and III only

I, II and III

22.

In which of the following processes is plant nutrient in the soil lost through gravity?

Capillarity

Erosion

Evaporation

Leaching

23.

A body of mass 20 kg falls from a height of 10 m. If g = 10.0 ms^-2, calculate the velocity of the body just before it touches the ground.

10.0 ms^-1

14.0 ms^-1

20.0 ms^-1

24.3 ms^-1

Just before the body touches the ground, the kinetic energy equals the potential energy.

Potential Energy Formula

Potential Energy (PE) = Mass (M) x Acceleration due to gravity (g) x Height (h)

PE = mgh

Kinetic Energy Formula

Kinetic Energy (KE) = $\frac{1}{2}$ x mass x velocity x velocity

KE = $\frac{1}{2}$ x mv²

Mass = 20 kg
Acceleration due to gravity = 10 ms^-2
Height = 10 m

Potential Energy = 20 x 10 x 10 = 2000 J

Kinetic Energy (KE) = $\frac{1}{2}$ x mass x velocity x velocity

$\frac{1}{2}$ x mass x velocity² = 2000

Mass = 20 kg

$\frac{1}{2}$ x 20 x velocity² = 2000

Note: 2 divides 20, 10 times

10 x velocity² = 2000

Divide both sides by 10

velocity² = $\frac{2000}{10}$

velocity² = 200

Take square root of both sides.

Velocity = $\sqrt{200}$ = 14.1421356237 ≈ 14.0 ms^-1

24.

A solution of 250 cm³ HCl has a concentration of 2 mol dm^-3. Determine the number of moles of the acid.

0.25 moles

0.50 moles

1.00 moles

1.50 moles

Since the concentration is in dm³, convert the cm³ volume to dm³ by dividing by 1000

250 cm³ = $\frac{250}{1000}$ = 0.25 dm³

Concentration Formula

Concentration = $\frac{Mole}{Volume}$

Mole = Concentration x Volume

Mole = 2 mol dm^-3 x 0.25 dm³ = 0.5 moles

25.

In which of the following blood vessels in the mammalian body would high levels of urea be found?

Hepatic artery

Hepatic vein

Pulmonary artery

Pulmonary vein

26.

Land breeze occurs when

cool wind blows across the land during the day.

warm air rises up from the sea during the day.

cool wind blows across the sea at night.

warm air rises up from the land during the day.

27.

The following statements are characteristics of large-scale industries except

volumes of products turned out are large.

many people are involved in its operation.

capital investment is large.

space of operation is limited.

28.

Muscles are mostly made up of

proteins.

starch.

fibre.

cellulose.

29.

Determine the volume of water required to change the concentration of 100 cm³ HCl from 0.5 mol dm^-3 to 0.1 mol dm^-3.

100 cm³

200 cm³

400 cm³

500 cm³

The initial and final moles are the same. Thus the mole doesn't change but only the concentration changes.

Initial molarity = Final molarity

Moles = Concentration x Volume

C₁ x V₁ = C₂ x V₂

C₁ = 0.5 mol dm^-3

V₁ = 100 cm³

C₂ = 0.1 mol dm^-3

0.5 mol dm^-3 x 100 cm³ = 0.1 mol dm^-3 x V₂

Divide both sides by 0.1

V₂ = $\frac{0.5 x 100}{0.1}$ = 500 cm³

The final volume must be 500 cm³

Volume of HCl + Water = 500 cm³

Volume of HCl = 100 cm³

100 cm³ + Water = 500 cm³

Water = 500 cm³ - 100 cm³

Water = 400 cm³

30.

A force moves a body through a distance of 15 m in the direction of the force. If the work done by the force is 45.0 J, determine the magnitude of the force.

3.00 N

3.15 N

6.00 N

6.75 N

Work Formula

Work done = Force x Distance

Work done = 45 J
Dstance = 15 m

45 = Force x 15

Divide both sides by 15

Force = $\frac{45}{15}$ = 3.00 N

31.

Which of the following statements are functions of soil air?

I. It is for respiration of plant roots.
II. It is for respiration of soil fauna.
III. It is for seed germination.

I and II only

I and III only

II and III only

I, II and III

32.

Digestion of food is completed in the

small intestine.

large intestine.

stomach.

rectum.

33.

Transistors can be used as

I. amplifiers.
II. switches.
III. temperature controls.

Which of the statements above is/are true?

I only

II only

I and II only

II and III only

34.

Sedimentary rocks are not resistant to weathering because, they

are formed from molten matter.

formed from other rocks.

have lines of weakness between mineral aggregates.

have lines of weakness between strata.

35.

The reaction represented by the equation

RCOOH + R^'OH ⇋ RCOOR^' + H₂O is an example of

esterification.

hydrolysis.

neutralization.

oxidation.

36.

All the following crops require staking as a cultural practice except

cowpea.

cucumber.

tomato.

yam.

37.

Which of the following lights will combine with red light to give white light?

Cyan

Green

Magenta

Yellow

38.

Which of the following organelles is called the power house of the cell?

Golgi complex

Mitochondrion

Nucleus

Endoplasmic reticulum

39.

The IUPAC name of the compound Mg(HCO₃)₂ is

magnesium hydrogen trioxocarbonate (III).

magnesium hydrogen trioxocarbonate (IV).

magnesium hydrogen trioxocarbonate (V).

magnesium hydrogen trioxocarbonate (II).

40.

Which of the following brooder house equipment confines day-old chicks?

Feed trough

Chick guard

Hover

Liter

41.

Symbiotic association in the root nodules occurs in

cocoyam.

millet.

rice.

soya bean.

42.

The method of fertilizer application which is most labour intensive and time-consuming is the

broadcasting method.

drilling method.

foliar method.

ring method.

43.

An electric kettle rated 1.5 kW operates at 200 V. Determine the current passing through the kettle.

7.5 A

133.3 A

201.5 A

300.0 A

Electric Power Formula

Power (P) = Current (I) x Voltage (V)

Power (P) = 1.5 kW = 1.5 x 1000 W = 1500 W

Voltage = 200 V

Electric Power Formula

Current (I) = $\frac{Power (P)}{Voltage (V)}$

Current (I) = $\frac{1500}{200}$ = 7.5 A

44.

The best way of storing yam tubers is

burying them in the soil.

keeping them in silos.

packing them on wooden platforms and in barns.

leaving them in the mounds for long periods.

45.

Blood pressure is highest at

pulmonary veins.

vena cava.

aorta.

ventricular diastole.

46.

The main constituent of natural gas is

ethane.

helium.

methane.

nitrogen.

47.

The SI unit of light intensity is

ampere.

candela.

kilogram.

kelvin.

48.

A 250 cm³ of 0.10 mol dm^-3 of KOH is to be prepared. Calculate the mass of KOH required.

[K = 39, O = 16, H = 1]

1.0 g

1.4 g

7.0 g

14.0 g

Concentration Formula

Concentration = $\frac{Mole}{Volume}$

Mole = Concentration x Volume

Mole Formula

Mole = $\frac{Mass}{Molar Mass}$

Concentration Formula

Concentration = $\frac{Mass}{Molar Mass}$ ÷ Volume

Concentration = $\frac{Mass}{Molar Mass x Volume}$

Mass = Concentration x Molar Mass x Volume

Since the concentration is in per dm³, convert the cm³ to dm³ by dividing by 1000

250 cm³ = $\frac{250}{1000}$ dm³ = 0.25 dm³

Concentration = 0.10 mol dm^-3

Molar mass = 39 + 16 + 1 = 56 g mol^-1

Note: unit for molar mass is grams per mole

Volume = 0.25 dm³

Mass = 0.10 mol dm^-3 x 56 g mol^-1 x 0.25 dm³ = 1.4 g

49.

The male and female sex cells are collectively called

foetus.

gamete.

seed.

zygote.

50.

A characteristics of sound that differentiates the same note played on different instruments is

frequency.

loudness.

pitch.

quality.

THEORY QUESTIONS

(a)

(i)

List three major types of weathering.

(ii)

Explain the role of temperature in weathering of rocks.

(b)

A 100 W heater is connected to a 240 V mains supply. Calculate the:

(i)

current drawn;

(ii)

resistance of the heater.

(c)

(i)

List three compounds which have electrovalent bond.

(ii)

Give two characteristics of electrovalent compounds.

(d)

(i)

What is rhesus factor?

(ii)

Explain briefly how the rhesus factor in humans could result in miscarriage.

Show Solution

(a)

(i)

Major types of weathering

1. Physical/mechanical weathering
2. Chemical weathering
3. Biological weathering

(ii)

Explanation of the role of temperature in weathering of rocks

1. When temperature rises, rocks expand and when temperature falls, rocks contract
2. The continuous expansion and contraction of rocks, cause cracks and eventual breakdown of the rocks to smaller pieces

(b)

(i)

Electric Power Formula

Power (P) = Current (I) x Voltage (V)

Power (P) = 100 W

Voltage = 240 V

Current Formula

Current (I) = $\frac{Power (P)}{Voltage (V)}$

Current = $\frac{100 W}{240 V}$ = 0.417 A

(ii)

Method I

Electric Power Formula

Power = Current² x Resistance

P = I²R

P = 100 W
I = 0.417 A

100 = 0.417² x R

R = $\frac{100}{{0.417}^{2}}$ = 575.079504742 ≈ 575 Ω

Method II

Voltage Formula

Voltage = Current x Resistance

Resistance Formula

Resistance = $\frac{Voltage}{Current}$

Voltage = 240 V
Current = 0.417 A

Resistance = $\frac{240 V}{0.417 A}$ = 575.5395683 ≈ 575.5 Ω

(c)

(i)

Compounds which have electrovalent bond

1. Sodium chloride/NaCl
2. Magnesium chloride/MgCl₂
3. Sodium Hydroxide/NaOH
4. Calcium Chloride/CaCl₂

(ii)

Characteristics of electrovalent compounds

1. Hard/Crystalline/solid
2. Soluble in water/insoluble n organic solvent/Kerosene,etc.
3. High boiling/melting point/high heat of fusion/Vaporization
4. Conduct electricity iin solution/molten state

(d)

(i)

Rhesus factor is a type of/inherited protein/antigen that may be present on the surface of a red blood cell.

(ii)

Explanation of how the rhesus factor could result in miscarriage

1. The problem arises when an Rh+ man marries a woman who is Rh- and their baby would be Rh+
2. In the event of leakage of blood during the pregnancy/birth from the mother to the foetus
3. The Rh antibodies of the mother get into contact with the Rh+ blood of the foetus resulting in antibody-antigen reaction
4. This destroys the foetus/causes miscarriage

(a)

(i)

Explain briefly how solar energy is used to generate electricity.

(ii)

State two other uses of solar energy.

(b)

State five ways of conserving water in the home.

(c)

(i)

State three management practices to ensure high yield in maize production.

(ii)

Explain how two of the management practices stated in (i) help in ensuring high yield of maize.

(d)

State

(i)

two effects of air masses on the environment.

(ii)

three ways by which global warming can be reduced.

Show Solution

(a)

(i)

Explanation of how solar energy is used to generate electricity

1. A photovoltaic cell/solar cell collects the sun's energy
2. The energy removes an electron from the cell/causes photoelectric effect
3. The electron then moves and this movement of electrons contribute electric current

(ii)

Other uses of solar energy

1. Heating water/Homes/Environment
2. Lighting homes/places
3. Drying clothes/fish/baked pots/earthen ware/seeds
4. Stimulates the skin to produce Vitamin D
5. Use in hydrological/water cycles
6. For photosynthesis in plants

(b)

Ways of conserving water in the home

1. Turn off tap intermittently while brushing teeth so as to have the water running only when washing
2. Fix leaks/leakages in pipe line/performing routine maintenance
3. Re-use of waste water for flushing toilet/watering plants where possible
4. Avoid using treated water for car washing
5. Flush toilet only when necessary
6. Lawn should be made of succulent/other plants that thrive under drought

(c)

(i)

Management practices to ensure high yield in maize production

1. Fertilizer application (at the right time)
2. Controlling of weeds
3. Controlling pests/disease
4. Harvesting/planting at the right time/early harvesting
5. Application of lime to increase soil pH
6. Using viable seeds
7. Ensure correct spacing/planting density/rotation with other crops
8. Water/irrigation

(ii)

Explanation of how management practices stated in help in ensuring high yield of maize

1. Fertilizer: provides sufficient nutrients
2. Controlling of weeds: Minimize/reduces competition for resources
3. Controlling pests/disease: keeps the crops health
4. Harvesting/planting at the right time/early harvesting: prevents invasion of pest in the field
5. Application of lime: to give them required pH of the soil for maximum growth
6. Using viable seeds: to ensure maximum germination
7. Ensure correct spacing/planting density/rotation with other crops: to reduce/minimize competition for resources
8. Water/irrigation: to maintain good soil temperature/to help dissolve the nutrients

(d)

(i)

Effects of air masses on the environment

1. Destruction of biodiversity
2. Destruction of the ozone layer
3. Makes environment dry/moist/influences humidity
4. Can create storm where two air masses of different temperatures meet
5. Can change the weather/climate
6. Makes environment hot/cold/vary environmental temperature
7. Causes acid rain, etc.

(ii)

Ways by which global warming can be reduced

1. Afforestation/planting of trees
2. Use of LPG (instead of wood for domestic fire)/reduce use of fossil fuels/Using renewable energy/Using solar energy to produce electricity
3. Use of HFCs instead of CFCs
4. Avoid/reduce bush burning
5. Avoid using driers to dry clothes/Use open air
6. Reduce the use of processed foods/eating plant rich diet
7. Using energy efficient appliances
8. Minimizing the use of cars/vehicles/automobiles
9. Replacing filters in air conditioners

(a)

(i)

Explain why aluminium resists corrosion but iron does not.

(ii)

State two methods of preventing iron from rusting.

(b)

(i)

Explain the term culling as used in livestock management.

(ii)

State three benefits of practising culling.

(c)

(i)

Distinguish between grafting and budding.

(ii)

Give three reasons for grafting and budding.

(d)

(i)

State the principle of conservation of energy.

(ii)

State the energy transformation that occur in each of the following devices:

(α)

a moving motorcycle;

(β)

a television set in operation.

Show Solution

(a)

(i)

Explanation of why aluminium resists corrosion but iron does not

1. The Aluminium oxide layer formed protects the aluminium from further oxidation

2. Iron does not form any layer which protects it from oxidation/Oxide formed by Iron flakes off exposing the iron for further oxidation

(ii)

Methods of preventing iron from rusting

1. Painting
2. Oiling/greasing
3. Electroplating
4. Galvanizing
5. Alloying
6. Organic/Powder coating
7. Sacrificial protection/Cathodic
8. Keep the iron dry and clean

(b)

(i)

Culling is the practice of removing all diseased/unproductive animals from the flock.

(ii)

Benefits of practising culling

1. Prevention of spread of diseases/promoting healthy growth of livestock/eradicating/eliminating hosts species/helps birds stay healthy
2. Reducing overcrowding/creation of space
3. Unproductive animals are gotten rid of
4. Reduction in losses that could have been incurred feeding unproductive animals/Economic gain
5. Improves growth rate of animals

(c)

(i)

Distinction between grafting and budding

In grafting, the upper part (scion) of one plant is transferred to grow on the root system (stock) of another plant (of the same species), whereas, in budding, a bud from one plant is transferred and allowed to grow on another plant.

(ii)

Reasons for grafting and budding

1. To change varieties
2. To take advantage of a particular root stock
3. To perpetuate clones
4. To produce certain plant forms/it enables effective use of a specific characteristic of plant
5. To repair damaged plants
6. To increase growth rate of seedlings/early production of fruits
7. It enables one plant which cannot produce viable seeds to be propagated
8. To produce plants more resistant to adverse conditions/diseases

(d)

(i)

The principle of conservation of energy states that energy is neither created nor destroyed but can be changed/transferred/transformed from one form to another

The principle of conservation of energy states that in a closed system, the total energy is constant.

(ii)

Energy transformation in

(α)

a moving motorcycle

Chemical energy to kinetic energy/sound energy/heat energy

Note: Start with chemical energy to score

(β)

a television set in operation

Electrical energy to light energy/sound energy/heat energy

Note: Start with electrical energy to score

(a)

(i)

What are secondary colours of light?

(ii)

Name the colour that results from the combination of each of the following pairs of colour of light:

(α)

red and green;

(β)

blue and green;

(γ)

red and blue.

(b)

(i)

Define the mole of a substance.

(ii)

Calculate the number of atoms in 18 g of magnesium metal.

[Mg = 24, Avogadro number = 6.023 x 10²³]

(c)

(i)

Differentiate between bone and cartilage.

(ii)

Name three parts of the human body where cartilages are found.

(d)

(i)

Explain the term deep litter system as used in poultry.

(ii)

Give three advantages of the deep litter system.

Show Solution

(a)

(i)

Secondary colours of light are colours obtained by mixing two primary colours of light.

(ii)

Secondary colours formed from the mixture of

(α)

Red and green

Yellow

(β)

Blue and green

Cyan

(γ)

Red and blue

Magenta

(b)

(i)

Mole of a substance is the amount of substance which contains same number of chemical units/atoms, molecules, etc. as there are carbon atoms in 12 g of carbon-12 isotopes.

Mole of a substance is the amount of substance which contains one Avogadro number of particles.

(ii)

Method I

Using the formula

Number of Atoms Formula

Number of atoms = Mole x Avogadro number

Mole Formula

Mole = $\frac{Mass}{Molar Mass}$

Mass of magnesium = 18 g

Molar mass = 24

Mole of magnesium metal = $\frac{18}{24}$ = 0.75 mol

Number of atoms = Mole x Avogadro number

Avogadro number = 6.023 x 10²³

Number of atoms in 18 g of magnesium metal = 0.75 x 6.023 x 10²³

Number of atoms in 18 g of magnesium metal = 4.515 x 10²³ atoms

Method II

Using proportionality

1 mole of Mg contains 6.02 x 10²³ atoms

0.75 mole of Mg contains 0.75 x 6.02 x 10²³ atoms

0.75 mole of Mg contains 4.515 x 10²³ atoms

(c)

(i)

Distinction between bone and cartilage

Bone is a hard/in elastic/tough/rigid connective tissue forming part of the skeleton. Cartilage is a soft/elastic/flexible connective tissue that protects the bone from robbing against each other.

(ii)

Parts of the human body where cartilages are found

1. Joint/Elbow/knee/Ankle/any correct named joint
2. End of Ribs/Ribs
3. Nose
4. Trachea/Bronchial tubes/Air ways
5. Larynx
6. External ear/Pinna/Ear
7. Epiglottis

(d)

(i)

Deep litter system is a management practice in poultry where large number of birds are kept in large room/enclosure covered with thick layers of wood shavings/straw/grass/foreign materials

(ii)

Advantages of the deep litter system

1. It makes management of large birds easy
2. Birds are protected from harsh weather conditions
3. There is less risk of predation and theft
4. It requires small space of land to operate/effective use of land space
5. It ensures effective use of labour/economical
6. It is good for commercial egg production
7. It is hygienic/safe to birds
8. It controls diseases
9. It increases efficiency of production

(a)

Explain how each of the following actions causes loss of soil nutrients:

(i)

crop removal;

(ii)

continuous cropping;

(iii)

drainage.

(b)

(i)

Give the reason for using each of the following devices in household wiring:

(α)

earthing;

(β)

stabilizer;

(γ)

fuse.

(ii)

Explain the behaviour of a p-n junction diode when it is forward biased.

(c)

State in which way each of the following factors is important in the germination of seeds:

(i)

water;

(ii)

oxygen;

(iii)

warmth;

(iv)

sunlight.

(d)

The table below shows a list of some chemical substances and the sources from which they are obtained but not correctly matched. In a tabular form, match each chemical substance with its correct source.

	Substance	Source
(i)	Ammonia	Lime water
(ii)	Potassium hydroxide	Sour palm wine
(iii)	Calcium oxide	Green vegetables
(iv)	Ethanoic acid	Ashes of plants
(iv)	Ascorbic acid	Decomposed organic matter

Show Solution

(a)

Explanation of loss of soil nutrients through

(i)

crop removal

Harvesting by taking the entire crop plant from the farm denies the land of organic matter that would have resulted from the decay of the plant.

Leaves the ground bare leading to loss of nutrients by erosion.

(ii)

continuous cropping

It leads to constant removal of nutrients from the land by plants. The land is not allowed to rest in order to regain fertility.

(iii)

drainage

Nutrients that dissolved in the soil water are removed together with the excess water/water washes away the top soil (humus) thereby depriving the soil of its nutrients.

(b)

(i)

Reason for using device in household wiring:

(α)

Earthing

To conduct excess charges/current on an appliance safely to earth

To prevent the user of the appliance from getting electric shock

It protects the circuit breaker/fuse/electrical appliances

(β)

Stabilizer

To keep the voltage through an appliance constant/Regulates the fluctuating voltage/current.

(γ)

Fuse

To cut power supply to an appliance/circuit when the current goes beyond acceptable level/to protect an appliance from being damaged by excessive current.

(ii)

Explanation of the behaviour of a P-N junction diode when it is forward biased

1. The junction narrows
2. Holes move across the junction to the N-type material/electrons move in the opposite direction into the P-type material
3. Much more current flows in the circuit

(c)

Importance of factors in the germination of seeds

(i)

Water

1. Enables food materials to dissolve and diffuse into the embryo
2. Imbibition of water activates the protoplasm of the cells of the seed
3. Softens the seed coat/makes the seed coat permeable for gaseous exchange
4. Activates enzymes (which break down food materials)

(ii)

Oxygen

Oxidizes food in the seed (to provide the embryo with energy required for its growth)

(iii)

Warmth

Provides suitable/adequate temperature for enzymes in the seed to act.

(iv)

Sunlight

Stimulate phytochrome (pigment) in seed that promote germination in some seed/ a type of light can promote/inhibit germination.

(d)

	Substance	Source
(i)	Ammonia	Decomposed organic matter
(ii)	Potassium hydroxide	Ashes of plants
(iii)	Calcium oxide	Lime water
(iv)	Ethanoic acid	Sour palm wine
(iv)	Ascorbic acid	Green vegetables

(a)

(i)

What is meant by insanitary condition?

(ii)

State three ways by which fire from electrical causes could be prevented.

(b)

(i)

Give three effects of ecto-parasites on cattle.

(ii)

List four methods of controlling ecto-parasites of livestock.

(c)

Describe briefly how a standard solution of sodium hydroxide is prepared in the laboratory.

(d)

(i)

Define displacement.

(ii)

A bird flies with a constant velocity of 100 ms^-1 for 10 minutes.

Calculate the magnitude of its displacement.

Show Solution

(a)

(i)

Insanitary condition refer to the situation/circumstances that might contaminate with dirt/filth/unclean/unhealthy environment that can lead to injury/health problems/spread diseases.

Insanitary condition refer to a condition which is dirty/dangerous for one's health due to lack of toilet facilities/drains/water making it difficult to keep things clean.

(ii)

Ways of preventing fire from electrical sources

1. Use only licensed electricians for installation/repair
2. Do a thorough check on electrical wiring before cutting through the wall/floor/ceiling
3. Inspect power tools regularly
4. Check insulated tools for damage before using them
5. Never modify electrical plugs
6. Keep extension cords in a safe place/in where they would not be stepped on/driven over
7. Ensure that all electrical components are kept dry
8. Avoid overloading sockets
9. Keep flammable materials away

(b)

(i)

Effects of ecto-parasites on cattle

1. Anaemia/loss of blood/weakness
2. Restlessness
3. Transmit diseases/health of the animal affected
4. Poor growth rate
5. Reduction in production
6. Reduction in economic value of animal
7. Damage to skin
8. Loss of weight/emaciation/animals grow lean/loss of appetite

(ii)

Method of controlling ecto-parasites of livestock

1. Rotate pasture to help prevent overgrazing to reduce the risk of parasites
2. Feed livestock in containers (instead of on the ground)
3. Ensure to clean feeders/water buckets/observe farm hygiene/ensure proper sanitation
4. Keep young animals in separate pastures from adults livestock
5. Dipping

(c)

Description of preparation of a standard solution of sodium hydroxide in the laboratory

1. Weigh a quantity of Sodium hydroxide crystals in a container/beaker
2. A small quantity of distilled water is added and the mixture stirred for all the solute to dissolve
3. The solution is transferred into a standard volumetric flask (using a filter funnel)
4. The beaker and the glass rod are rinsed with distilled water into the volumetric flask
5. The volumetric flask is corked and shaken
6. More distilled water is added till the solution reaches its calibrated mark and then shaken

(d)

(i)

Displacement is the distance moved in a given/specified direction.

Displacement is the change in position of a body in a given/specified direction.

(ii)

Displacement Formula

Displacement = Velocity x Time

Velocity = 100 ms^-1

Time = 10 minutes = 10 x 60 s = 600 s

Note: the unit of time is seconds (s) hence the minutes must be converted to seconds.

Displacement = 100 ms^-1 x 600 s

Displacement = 60,000 m

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