i)

Differences between a rhizome and a stem tuber

ii)

Examples of a rhizome and a stem tuber

Rhizome: Ginger, Canna Lily, Fern, Elephant grass, Tiger nuts
Stem tuber: Yam, Irish potato/potato

i)

Density is defined as mass per unit volume of a substance

OR

Density = $\frac{\mathrm{Mass\; of\; substance}}{\mathrm{Volume\; of\; substance}}$

ii)

How to make a body which sinks in water float

1. Make the body hollow/shape body into a bowl
2. Decrease the density of the body to lower than the density of water by increasing the volume of the body

(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)

Surface tension is the property of a liquid which makes the surface behave as if it were a stretched elastic skin.

ii)

Household devices that make use of surface tension

1. Umbrellas
2. Raincoats
3. Tents
4. Canopies

iii)

Umbrellas/Raincoats/Tents/Canopies made of canvas do not leak because the surface tension of the water prevents the water from passing through the tiny holes in them

OR

In umbrellas/raincoats/tents/canopies made of canvas, water forms films like stretched elastic skin over each pore which prevents water from passing through.

i)

Constipation is the difficulty in freeing/expelling faces from the bowels regularly.

OR

Constipation is the difficulty in defecating regularly.

OR

Constipation is the irregular and difficult passage of faeces.

ii)

Ways by which constipation can be prevented

1. Take meals at regular times
2. Do not overeat
3. Undertake a good amount of exercise
4. Take in enough water
5. Eat plenty of fruits, vegetables and rouphages
6. Free bowels regulary/attend nature's call regularly

i)

Blue

ii)

Reaction is complete

OR

Reaction is slightly acidic

OR

Sodium hydroxide has been neutralized

iii)

Sodium chloride/NaCl/common salt

iv)

NaOH + HCl → NaCl + H₂O

i)

Digestion is the breaking down of complex or insoluble food substances into simple and absorbable forms in the body of mammals.

ii)

How food is digested in the stomach

1. Slightly alkaline food enters the stomach
2. The walls of the stomach produce/secrete gastric juice which is mixed with the food
3. The gastric juice contains dilute hydrochloric acid and protein digesting enzymes (proteases)
4. The dilute hydrochloric acid provides/creates acidic medium/condition in the stomach
5. The enzymes break down the large protein molecules into simpler units (amino acids)
6. Only protein molecules are digested in the stomach

i)

Eclipse of the sun is the blocking of the light from the sun by the moon from reaching portions/parts of the earth.

OR

Eclipse of the sun occurs when the moon comes between the sun and the earth so that the moon's shadow is cast on the earth.

ii)

Total and partial eclipse

The shadow which the moon casts over the earth has both umbra (total darkness) and penumbra (partial darkness).

People in the direct region of the eclipse observe total darkness/umbra which is the total eclipse.

Those slightly out of the region observe partial darkness/penumbra which is the partial eclipse.

People outside the shadow regions will see the sun as normal.

i)

Differences between a physical change and a chemical change

ii)

Examples of a physical change

1. Dissolving sugar in water
2. Sand and sugar mixture
3. Sulphur and iron filing mixture
4. Melting of candle
5. Melting of ice
6. Expansion of copper
7. Filtration
8. Freezing of water
9. Grinding of chalk
10. Boiling of an egg for five minutes
11. Chewing of meat in the mouth for two minutes
12. Pounding of boiled cassava and plantain together into fufu

Examples of a chemical change

1. Burning wood
2. Reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl)
3. Rusting of iron
4. Cooking of food
5. Fermentation
6. Chewing of piece of bread in the mouth for two minutes

(i)

Density is the mass per unit volume of a substance

OR

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

(ii)

Determination of the density of stone

1. Measure/weigh the mass of stone by means of a beam/chemical balance as M g
2. Fill a large measuring cylinder with water to a suitable level and record the volume as V₁ cm³
3. Tie the stone with thread and gently lower it into the water in the measuring cylinder and record the new volume as V₂ cm³

The density of the stone is then calculated as follows:

Volume of stone = V₂ cm³ - V₁ cm³

Mass of stone = M g

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

Density of the stone = $\frac{\mathrm{M\; g}}{({\mathrm{V}}_2-{\mathrm{V}}_1){\mathrm{cm}}^3}$

(i)

Alcohol and water → Distillation/fractional distillation

(ii)

Salt and water → Distillation/Evaporation and condensation

(iii)

Powdered charcoal and iron filings → Use of magnet

(iv)

Powdered chalk and water → Filtration/decantation

(i)

I = beaker
II = residue/particles/cotton wool/mixture/filter paper
III = filtrate

(ii)

Methods of Separation

(iii)

Class of mixtures

1. Solid - liquid mixture
2. Liquid - solid mixture

(iv)

Reason for the class of mixture

Because there is residue on the filter paper and filtrate in the beaker

(v)

possible component of the mixture in set-up B

- iron fillings/any magnetic substance
- powdered sulphur
- sand
- powdered chalk
- powdered charcoal
- any non-magenetic substance

(vi)

Function of part labelled IV (Retort/Clamp Stand)

It holds the funnel in place/holds the clamp

(i)

The system illustrated is respiratory system

(ii)

Name of the parts labelled

I = Larynx/Voice Box
II = Trachea/windpipe
III = Bronchus
IV = lung

(iii)

Role of the part labelled I (Larynx)

1. Allows air to pass through it/breathing
2. Prevent food and drink from blocking the airways
3. Produces sound/phonation

(iv)

Diseases of the respiratory system

1. Tuberculosis/T.B.
2. Bronchitis
3. Pneumonia
4. Whooping cough
5. Lung cancer
6. Influenza
7. Asthma
8. Bronchiectasis
9. Idiopathic pulmonary fibrosis/pulmonary disease
10. Common cold
11. Covid-19

(i)

Rain gauge

(ii)

Name of the parts labelled

I = funnel
II = measuring cylinder
III = rain water/water

(iii)

Use of the parts labelled I (funnel) and II (measuring cylinder)

I - directs rain water into the measuring cylinder

II - use to measure the amount/volume of rain water/collect rain water

(iv)

Ecological factor measured

Rainfall/amount of rainfall/rain

(v)

Importance of ecological factor measured

1. Protects plants roots from injury
2. Causes erosion
3. Causes leaching
4. Needed for seed germination
5. Promotes activities of soil organisms
6. Aids in easy tillage of soil
7. An agent of weathering of rocks in the soil
8. Dissolves plant nutrients for easy absorption
9. Makes soil fertile
10. Determine the type of crop to grow
11. Used for photosynthesis

(vi)

Handfork

(vii)

Use to loosen hard soil surface after heavy rainfall

(i)

Name of the components labelled

I = cell
II = switch/key
III = lamp/bulb

(ii)

Type of arrangement of resistors (R) in B is parallel

(iii)

A - makes III/bulb dim
B - makes III/bulb bright

(iv)

Reasons

A - the resistors in series have an increased resistance

B - the resistors in parallel have decreas resistance hence keep the bulb bright