i)

A transistor is a three terminal (a base, emitter and collector) semiconductor device.

ii)

Uses of a transistor

1. Used as an amplifier
2. Used as a switch
3. Used as a rectifier
4. Used for tuning in radios
5. Used as a voltage/current regulator

i)

Suitable solvents for grease

1. Petrol
2. Kerosene
3. Methylated spirit

ii)

Suitable solvents for ink stain

1. Milk
2. Alcohol
3. Parazone
4. Shaving cream
5. Kerosene

iii)

Suitable solvents for starch

1. Alcohol
2. Acetone

iv)

Suitable solvents for cube sugar

Water

v)

Suitable solvents for oil paint

1. Turpentine
2. Kerosene
3. Petrol
4. Thinner

vi)

Suitable solvents for iodine

1. Ethanol/Alcohol
2. Potassium iodide solution

i)

Respiratory organ is an organ used by living organisms for gaseous exchange

ii)

Structures of the respiratory system of humans

1. Trachea
2. Lungs
3. Alveolus
4. Larynx
5. Diaphragm
6. Bronchus/Bronchi
7. Nostril/Nose
8. Nasal cavity
9. Intercostals muscle
10. Ribs
11. Pharynx

i)

Agricultural chain is a series of stages that are connected in the production of agricultural goods/services.

ii)

Types of agricultural chain

1. Production
2. Processing
3. Supply
4. Value

(i)

What happens when photosynthesis occurs in a leaf

Plants take in carbon dioxide (CO_{2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. Light is also absorbed by chlorophyll}

(ii)

pollination is the transfer of pollen from the anther of a flower to the stigma of the same flower or another flower of the same type

(i)

A physical quantity is any physical property of a material or substance that can be quantified, that is, can be measured using numbers

(ii)

1. Mass
2. Force
3. Density
4. Length
5. Temperature
6. Volume
7. Electric current
8. Velocity
9. Time

(i)

Importance of light in crop production

1. Needed for photosynthesis
2. Affects developments of fruits/growth of vegetative parts of crops
3. Absence of light results in weak stem

(ii)

Importance of temperature in crop production

1. Required for germination
2. Delays ripening of fruits when temperature is low
3. High temperature can cause evaporation from the soil causing water deficit for crops
4. High temperature can scorch the leaves of crops
5. Needed for photosynthesis/growth and development of plants

(i)

A lever is a simple machine which consists of a rigid bar/rod free to turn about a fixed turning point called the fulcrum/pivot.

(ii)

(i)

Pollination is the transfer of pollen grains from the anther of a flower to the stigma of the flower or another flower of the same species.

(ii)

Agents of pollination

1. Wind
2. Animal (Birds, Bats, Man)
3. Insect
4. Water/Rain

(i)

An alloy is a uniform/homogeneous mixture of a metal and another metal or a non-metal.

(ii)

Compositions of alloys

Bronze → Copper and Tin
Brass → Copper and Zin
Steel → Iron and Carbon
Duralumin → Aluminium, Magnesium, Copper and Manganese

(i)

How a shadow can be formed

(ii)

Change in volume = (75 - 50) cm³ = 25 cm³

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

Method I

Calculating density in kg dm^-3

Note: when using the mass in kilogram (4 kg) the volume must be in dm³.

25 cm³ = $\frac{25}{1000}$ = 0.025 dm³

Density = $\frac{4}{0.025}$ = 160 kg dm^-3 or 160 kg/dm³

Method II

Calculating density in g cm^-3

Note: when expressing the density in g cm^-3, the kilogram must be changed to gram.

4 kg = 4 x 1000 g = 4000 g

Density = $\frac{4000}{25}$ = 160 g cm^-3 or 160 g/cm³

Note: Mark is deducted for answer without correct unit

(iii)

Precautions that must be taken to obtain reliable results

1. The object should be dropped gently to avoid splashing the water
2. The volume should be read at the correct meniscus

(i)

Composting

1. Microorganisms in organic matter make use of oxygen
2. and decompose/breakdown organic matter into nutrients

(ii)

Recycling

1. Involves processing/conversion/physically and chemically changing waste materials
2. Into new products

(iii)

Incineration

1. Involves burning of waste materials at high temperatures
2. and converting them into gas/ash to destroy contaminants

i)

The two elements that combines to form ammonia gas

1. Nitrogen
2. Hydrogen

ii)

Balanced chemical equation for the formation of ammonia

N₂ + 3H₂ → 2NH₃

i)

Galaxy is a group of stars.

OR

Galaxy is a system of stars,gases,dust/dark matter held together in the heavens/space.

OR

Galaxy is a collection of billions of stars that show a common gravitational link.

ii)

Relationship between stars and galaxies

Galaxies are held together by gravitational attraction much like a solar system while stars in the solar systems combine to form galaxies

OR

Stars makes up the galaxies

OR

Galaxies are made up of several billions of Stars

iii)

Milky way is the galaxy that contains the solar system and the earth.

OR

Milky way is a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.

i)

Physical properties of water

1. Odourless
2. Colourless
3. Tasteless/insipid
4. Freezes at 0^oC
5. Boils at 100^oC
6. Universal solvent
7. Exists in three states
8. Has a density of 1g/cm³ (at 4^oC)
9. It is transparent
10. It has a neutral pH/pH = 7
11. High surface tension

ii)

Why water is neutral

When red litmus paper or blue litmus paper is dropped in a sample of water, there is no change in colour.

i)

Functions of nitrogen in plants

1. For plant growth/vegetative growth
2. Increases yield of straw
3. A constituent of organic compound of plants
4. For plant development
5. Increases seed and fruit production
6. To make proteins
7. To make chlorophyll

ii)

Functions of potassium in plants

1. Plays an important role in plant metabolism
2. Plays an important role in translocation of starch to growing parts
3. Plays an important role in carbohydrate formation
4. Neutralization of organic acids
5. Strengthens straw and stalk of plants
6. Aids absorption of nutrients
7. Helps to reduce diseases in plants
8. Helps to produce quality fruit and promotes seed development
9. Activates enzymes for photosynthesis and respiration
10. Helps build proteins
11. Aids absorption of nutrients

i)

Human activities that disrupt the carbon cycle

1. Destruction of forest/cutting of trees/lumbering
2. Bush burning
3. Burning of fossil fuels

ii)

Effects of the disruption of the carbon cycle on the environment

1. Global warming/rise in temperature/greenhouse effect/affects climate
2. Reduction in oxygen
3. Rise in sea level/flooding/melting of ice
4. Animals/plants become endangered/extinct
5. Prolonged drought
6. Reduction in rainfall

i)

Density is the mass per unit volume of a body

OR

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

ii)

Density = $\frac{\mathrm{Mass}}{\mathrm{Volume}}$

Density x Volume = Mass

Divide both sides by Density

Volume = $\frac{\mathrm{Mass}}{\mathrm{Density}}$

Mass = 50 kg
Density = 2kg/m³

Volume = $\frac{50}{2}$ = 25 m³