(i)

Water cycle is a set of natural processes that indicate the repeated use and release of water.

OR

Water cycle is a set of natural processes that describes how water evaporates from the surface of the earth into the atmosphere, cools/condenses into rain or snow in the clouds and falls again to the surface of the earth as rain or precipitation.

(ii)

Processes involved in the water cycle

1. Evaporation (from water sources)
2. Transpiration (from leaves of plants)
3. Respiration (from humans and animals)
4. Cooling/condensation of vapour (to form clouds or drops of water)
5. Sublimation
6. Falling of rain/precipitation/falling of snow
7. Collection into water sources
8. Used by plants/animals (to start the cycle again)

(i)

Ways of protecting people from the effects of radioactivity

1. Evacuation of people/resettle people/increasing the distance from radiation source
2. Sheltering in rooms
3. Use of non-radioactive iodine to prevent uptake of radioactive iodine by thyroid gland
4. Keeping radiation detector
5. Educating people
6. Wearing of protective clothing/shield/face mask/respirator
7. Shortening the time of exposure
8. Avoid drinking/eating contaminated water or food

(ii)

Uses of nuclear energy

1. Production of electricity
2. Nuclear medicine/medical uses/human health
3. Heating
4. Space missions
5. Used in agriculture or preservation of food/sterilization of insects/pests or plant mutation/breeding
6. Used in small batteries in exploring space
7. Propulsion of space craft
8. Manufacture of atomic bomb
9. Hydrogen production/fertilizer production
10. In submarines
11. Research
12. Sea water desalination

(i)

(ii)

Diseases that affect maize

1. Smut
2. Rust
3. Streak

(i)

Names of biological systems which help to co-ordinate the body's activities

1. The nervous system
2. The hormonal/endocrine system

(ii)

Hormones produced by the pancreas

1. Insulin
2. Glucagon
3. Pancreatic polypeptide
4. Somatostatin

(iii)

The disease condition associated with the failure of the pancreas to produce sufficient hormone is diabetes.

(i)

Carbon and oxygen → Covalent bond

(ii)

Hydrogen and sulphur → Covalent bond

(iii)

Copper and oxygen → Ionic/electrovalent

(iv)

Carbon and hydrogen → Covalent bond

(i)

Distinction between permanent magnet and temporary magnet

(ii)

(i)

Decombing is the removal of combs of poultry/young birds to prevent restlessness infection caused by flies or for them to grow fat or avoid being pecked by others.

(ii)

Reasons for castrating farm animals

1. To remove odour
2. To fatten the animal/to facilitate growth
3. To prevent sexually transmitted diseases/sexual desire
4. To make animal docile/to reduce aggression/reduces sexual desire
5. To prevent in-breeding/indiscriminate mating
6. Minimizes stress on the animal, when done close to birth/just after birth

(i)

Functions of the human ear

1. For hearing
2. For balancing

(ii)

The structures in the ear that is responsible for hearing

1. Cochlea
2. Auditory nerve
3. Pinna
4. Eardrum
5. Ear ossicles
6. Auditory canal

The structure in the ear that is responsible for balancing

Semi-circular canals

(i)

Differences between red blood cells and white blood cells

(ii)

Expected changes that will occur in the composition of the blood leaving a muscle of a person soon after a period of vigorous activity

1. There is increase in carbon dioxide
2. There is decrease in oxygen
3. There is decrease in glucose

(i)

Difference between a saturated hydrocarbon and an unsaturated hydrocarbon

Saturated hydrocarbons are hydrocarbons/compounds which have molecules containing only single covalent bonds whereas/while unsaturated hydrocarbons are hydrocarbons/compounds with double or triple bonds between carbon atoms.

(ii)

(i)

How a p-n junction diode is formed

A p-n junction diode is formed by doping one side of a semi-conductor with trivalent/acceptor impurity and the other side with a pentavalent/donor impurity

(ii)

How a p-n junction diode can be forward biased

This can be done by connecting the p-type semi-conductor of a diode to the positive terminal of a cell and the n-type to the negative terminal of the cell.

(i)

Elements which are positive ions

C and D

Note:

Positive ion/cation is formed when an atom loses one ore more electrons making the number of protons more than the electrons.

C has 12 protons and 10 electrons hence C has lost 2 electrons hence it is +2 ion

D has 11 protons and 10 electrons hence D has lost 1 electron hence it is +1 ion

(ii)

Elements which are negative ions

A and B

Note:

Negative ion/Anion is formed when an atom gains one ore more electrons making the number of electrons more than the protons.

A has 8 protons and 10 electrons hence A has gained 2 electrons hence it is -2 ion

B has 17 protons and 18 electrons hence B has gained 1 electron hence it is -1 ion

(iii)

Elements which can form isotopes

B and E

Note:

Isotopes possess the same number of protons but different number of neutrons.

B and E have the same number of protons (17) but different number of neutrons (18 and 20 respectively)

(i)

Causes of uneven heating of the earth's surface

1. Curvature of the earth's surface/the angle at which the sun's rays strike the earth/the earth is a sphere with equator heated more intensely than the poles
2. Revolution of the earth around the sun
3. Rotation of the earth on its axis
4. Differences in land and sea temperatures
5. The earth covered primarily with land and water which get heated and cool at different rates

(ii)

Characteristics of westerlies

1. They are hot air
2. They are from the equator to the poles
3. They have low density

(i)

Functions of the mammalian teeth

(ii)

How the structure of the incisor is adapted for its function

It has sharp or chisel-shaped edge

How the structure of the canine is adapted for its function

It has pointed edge/it is conical

How the structure of the molar is adapted for its function

It has flat/cusped/ridged surface

(i)

Diseases that affect poultry

1. Gumboro
2. Newcastle
3. Marek's/fowl paralysis
4. Fowl pox/Avian flu/bird flu
5. Pullorum/bacillary white diarrhea
6. Foot rot
7. Ring worm
8. Chronic respiratory disease
9. Fowl typhoid

(ii)

Diseases that affect cattle

1. Foot-and-mouth disease
2. Rinderpest
3. Cervico-vaginitis
4. Anthrax
5. Brucellosis/contagious abortion
6. Mastitis
7. Babesiosis (red water/tick fever)
8. Rabies
9. Tuberculosis
10. Footrot
11. Mad-cow disease

(i)

Ways in which parallel wiring system in households is important

1. The same voltage is supplied to all lamps/all lamps receive their required currents/it ensures that lamps are bright
2. When a lamp blows, it does not affect the functioning of other lamps/it is safe/reliable
3. Lamps are controlled by individual switches/lamps can be turned on and off independently
4. It is simple to design
5. It allows additional components/lamps

(ii)

Energy = Power x Time

1 hour = 60 x 60 s = 3600s

Note: the S.I unit for time is second hence you have to convert the hour to second.

Power = 2kW = 2 x 10³W

Energy = 2 x 10_{3 x 3600 J}

Energy = 7,200,000 J

Energy = 7.2 x 10⁶ J

(i)

Management practices are husbandry activities carried on animals to ensure proper growth or good health of the animals.

(ii)

Management practices undertaken in pig production

1. Clipping of needle teeth
2. Creep feeding
3. Iron injection
4. Bathing
5. Weaning
6. Castration
7. Fostering
8. Disease and pest control
9. Record keeping
10. Ensuring good sanitation control

(i)

Momentum is the product of mass and velocity of a body.

(ii)

Force = 50 N

Acceleration due to gravity (g) = 10ms^-2.

Mass = $\frac{50}{10}$ = 5 kg

Momentum = Mass x Velocity

Velocity = 20 m/s

Momentum = 5 kg x 20 m/s = 100 kgms^-1

(i)

Mode of dispersal of fruits

(ii)

Features that adapts fruits for dispersal

Pawpaw

Possession of fleshly mesocarp/It appears attractive

Silk cotton

Presence of floss/it is light

Pride of Barbados

Unequal drying of pods

(i)

Slope (S) = $\frac{\mathrm{Change\; in\; the\; Y\; -\; axis}}{\mathrm{Change\; in\; the\; X\; -\; axis}}$ = $\frac{{\mathrm{Y}}_2-{\mathrm{Y}}_1}{{\mathrm{X}}_2-{\mathrm{X}}_1}$

From the points A(39, 19) and B(84, 42)

Slope = $\frac{\mathrm{42\; -\; 19}}{\mathrm{84\; -\; 39}}$ = 0.5 cm³/g

(ii)

S^-1 = $\frac{1}{\mathrm{S}}$ = $\frac{1}{0.5}$ = 2 g/cm³

(i)

When mass is 35 g, volume = 17.5 cm³

Note:

Value at a grid = Number of grids from 0 x Value per grid

Volume = 35 grids x 0.5 = 17.5

(ii)

When volume is 22.5 cm³, mass = 45 g

Note:

Number of grids for 22.5 cm³ = $\frac{22.5}{0.5}$ = 45 grids from 0