(i)

Function of labelled parts

I → Carries blood from the heart/left ventricle to the circulatory system
II → Brings (oxygenated) blood from lungs to heart/left auricle/atrium
IX → Brings (deoxygenated) blood from the body to heart/right atrium/right side of heart
X → Carry (oxygen deficient) blood from heart to lungs/right side of heart/right ventricle to lungs

(ii)

Why the left lower part of the heart has a thicker muscle

Contracts to pump (oxygenated) blood with high pressure to all parts of the body

OR

To generate high pressure to allow blood to reach all parts of the body

(iii)

Ways by which the flow of blood to and from the mammalian heart can be kept at acceptable levels

1. Exercising
2. Not smoking
3. Taking iron rich foods/balanced diet
4. Regulating one's blood pressure
5. Stress management
6. Get enough sleep
7. Healthy weight
8. Limit alcohol consumption
9. Manage diabetes
10. Regular health check-up

(iv)

Parts of the heart where oxygenated blood can be found

1. Aorta
2. Pulmonary vein
3. Left atrium
4. Left ventricle

(i)

How P (Maize grains) is planted on seedbed

1. Make holes (using cutlas or stick/dibber)
2. Place 2 or 3 seeds per hole and cover with soil

How Q (Tomato seedlings) is planted on seedbed

1. Remove a plant seedling from a nursery gently
2. Place the seedling in a prepared hole
3. Firm the soil around the seedling with hands
4. Water immediately

How R (Cassava cuttings) is planted on seedbed

1. Dig a hole/loosen the soil/dig trenches
2. Turn the cutting with the nodes/buds facing upwards
3. Place (two thrifts of) cutting into the hole
4. Firm soil around the cutting

(ii)

Conditions under which R(Cassava cuttings) can be cultivated to produce high yield

1. Adequate rainfall/water/irrigation
2. Fertile soil
3. Soil with good structure
4. Absence of diseases
5. Absence of pests
6. Sunlight

(i)

Function of labelled parts

I → Converts chemical energy to electrical energy/generates voltage
II → Closes and opens circuit/allows charges to flow or not flow
III → Stores electric charges
IV → Opposes flow of charges/current

(ii)

V = IR

R = $\frac{\mathrm{V}}{\mathrm{I}}$

Voltage (V) = 2.4 V

Current (I) = 0.8 A

Resistance (R) = $\frac{\mathrm{2.4\; V}}{\mathrm{0.8\; A}}$ = 3 Ω

Note: Mark is deducted for answer without a unit (Ω)

(iii)

Way of conserving the value of the part labelled I (Cell/Battery) in the circuit

Open key/switch when not taking readings.

(iv)

Observations that can be made when the circuit is closed

1. Ammeter will read/deflect
2. Voltmeter will read/deflect

(i)

Description of the process of the experiment

1. Make the set-up as shown in the diagram
2. Put two immiscible liquids into the separating funnel/I
3. Allow the mixture to stand
4. And separate into two layers
5. Open the tap to drain the liquid at the bottom into the conical flask/III
6. Close the tap after draining the liquid at the bottom

Note: the steps must be in sequence. When sequence is broken, marking is stopped.

(ii)

Function of the labelled parts

II → Regulate/control of the flow of liquid
IV → To hold the separating funnel

(iii)

Precautions that should be taken to obtain reliable results when performing this experiment

1. The tap should be opened gently to release only the bottom liquid
2. The retort stand should be firm enough to hold the separating funnel
3. The mixture should be left to stand for sometime to settle and separate
4. The retort stand should be placed on a flat surface

(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)

Herbivore is an animal that feeds on plants only

Examples: Goat, rabbit, sheep, deer, cow, elephant, giraffe, horse

(ii)

Carnivore is an animal that feeds on the flesh of other animals only

Examples: Lion, wolf, leopard, hyena, polar bear, cat, cheetah, giant panda, felidae, tiger, sharks, venus fly trap

(iii)

Omnivore is an animal that feeds on both plants and animals

Examples: Man, bears, birds, dog, raccoons, fox, certain insects

(i)

A vector is an agent/organism that transmits/spreads disease causing organisms/pathogens from diseased organisms to healthy ones.

(ii)

(i)

Systematic name of CaCo₃

Calcium trioxocarbonate (IV)

(ii)

Systematic name of FeS

Iron (II) sulphide

(iii)

Systematic name of NaCl

Sodium chloride

(iv)

Systematic name of NaOH

Sodium hydroxide

(i)

Properties that are common to all states of matter

1. Matter occupies space/has volume
2. Matter has weight/mass

(ii)

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

Mass = 60 g

Volume = Final Volume - Initial Volume

Volume = 75 cm³ - 60 cm³
Volume = 15 cm³

Density = $\frac{\mathrm{60\; g}}{\mathrm{15 }{\mathrm{cm}}^3}$

Density = 4 gcm^-3

i)

Difference between organic fertilizer and inorganic fertilizer

Organic fertilizer is obtained from plant and animals whilst inorganic fertilizers are obtained from artificial/synthetic/non-living/chemical materials.

ii)

Effects of inorganic fertilizer on the environment

1. It pollutes water bodies/causes air or land pollution
2. It increases soil acidity
3. It kills plants and other organisms in the soil

i)

unripe lemon juice → acid

ii)

wood ash → base

iii)

liquid in a car battery → acid

iv)

bicarbonate of soda → base

i)

Fruit is a structure that develops from a fertlized ovary and contains a seed/seeds.

ii)

Differences between a fruit and a seed

i)

Effects of heat on plastics

1. It melts
2. It burns

ii)

Effects of heat on alcohol

1. It expands
2. It evaporates
3. It boils

iii)

Effects of heat on metal rod

1. It expands
2. It melts
3. It bends

i)

An alloy is a uniform/homogenous mixture of two or more metals or a metal and non-metal.

ii)

Diffusion is the process whereby molecules/particles of a liquid/gas move from a region of higher concentration to a region of a lower concentration until they are uniformly spread throughout an occupied space.

iii)

A colloid is a suspension in which the suspended particles are very small in size but bigger than the molecules of the solvent and are permanently suspended/does not settle on standing.

i)

Examples of alloy

1. Bronze
2. Brass
3. Steel
4. Solder
5. Duralumin
6. Cupronickel

ii)

Examples of colloid

1. Emulsion paint
2. Fog
3. Smoke
4. Milk
5. Toothpaste
6. Mist
7. Soap lather
8. Clay in water
9. Chalk in water
10. Gel
11. Aerosols

i)

Pollution is the release of toxic/harmful/poisonous substances into the environment.

ii)

i)

Potential energy

ii)

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

Weight = Mass x Acceleration due to gravity

Potential Energy = Weight x Height

Weight = 50 N
Height = 15 m

Potential Energy = 50 N x 15 m = 750 J