(i)

Substances that are excreted from human body

1. Urea
2. Carbon dioxide
3. Salt
4. Bile pigment

(ii)

Organs in humans which perform excretory functions

1. Liver
2. Skin
3. Lungs
4. Kidneys

(i)

Grafting is a process in which part of different plants known as the shoot/scion is connected/joined to another plant of the same species known as the stock to grow as one plant.

(ii)

Benefits of Grafting

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

(i)

Ways in which scientific methods is important

1. It helps the scientist to easily identify Problems
2. It provides logical procedure at drawing valid conclusions

(ii)

Reason for laboratory rules:

(i)

Earthing is the transfer of electrical charges from the atmosphere directly to the earth through a wire buried in the ground. This is done to conduct excess charges/current on an appliance safely to earth or to prevent the user of the appliance from getting electric shock or to protect the circuit breaker/fuse/electrical appliances

(ii)

Sources of electric power generation

1. Battery/Cell
2. Solar
3. Wind
4. Biogas
5. Nuclear
6. Hydro/water
7. Diesel

(i)

Temporary hard water is the hardness of water caused by the presence of hydrogen carbonates (bicarbonates) of calcium and magnesium and can be softened by boiling/heating.

(ii)

Chemical equation to show how the temporary hard water can be softened by heating

Ca(HCO₃)₂(aq)→CO₂(g)+H₂O(l)+CaCO₃(s)

OR

Mg(HCO₃)₂(aq)→CO₂(g)+H₂O(l)+MgCO₃(s)

(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)

Food processing is the chemical operations on food in order to preserve it.

(ii)

(i)

Benefits that Ghana could derived from nuclear energy

1. For generation of Electricity
2. For the treatment of Cancer
3. For research
4. For the production of nuclear weapons

(ii)

Types of nuclear radiation

1. Alpha particles
2. Beta Particles
3. Gamma rays

(i)

Kenkey production → Fermentation

(ii)

Soap production → Saponification

(iii)

Salt production → Evaporation

(iv)

Vegetable oil production → Fermentation / Chemical extraction

(v)

Gari processing → Fermentation / Evaporation

(i)

Micronutrients in the soil

1. Chloride
2. Iron
3. Boron
4. Copper
5. Nickel

(ii)

Distinction between broadcasting and side dressing methods of fertilizer application

Broadcasting methods of fertiizer application involved the use of hand to spread the fertilizer over the soil whilst side dressing is when the fertilizer is placed in one particular spot near the plant or the the roots of grain crops

(i)

Distinction between conductors and semiconductors

Conductors are materials which allow electrons to pass through them whilst semiconductors are solid materials which electrons are held in covalent bond or materials whose conductivity lies between conductors and insulators.

(ii)

Appliances in a home which use semiconductors

1. Solar panel
2. LED Bulbs
3. Microwave
4. Central Processing Unit (CPU)
5. Washing Machines
6. Radio Sets
7. TV sets

(i)

Conditions to be considered when selecting viable seeds for planting

1. Cost of Seed
2. Desired Colour
3. Moisture content of the seed
4. Seed must be free from infection
5. only whole seed must be selected

(ii)

Characteristics of good seeds

1. Free from Dirt
2. Disease Free
3. Free from Pest
4. Free from holes

(i)

Ohm's law states that the current flowing through a metallic conductor at a constant temperature is proportional to the potential difference across it.

OR

V = IR,
where V = voltage or P.d
      I = current,
      R = resistance.

(ii)

V = IR

Current(I) = 10 A
Resistance(R) = 12.5 Ω

Potential difference/voltage = 10 x 12.5 V = 125 V

(i)

Distinction between a pandemic and an epidemic

Pandemic is a disease occurring world wide over wide area crossing international boundaries which usually affects a large number of people whilst epidemic is a disease that affects a large number of people within a community or population/region.

(ii)

Roles of the World Health Organisation in the management of the COVID-19 disease

1. Establishes a Respond fund
2. Researches on the COVID-19 disease
3. Distributes very important medical supplies
4. Provides education on the disease
5. Advices countries on critical interventions

(i)

Instruments used for measuring the volume of liquids accurately

1. Pipette
2. Burette
3. Volumetric Flask
4. Calibrated Beaker

(ii)

Reasons why accurate measurement is necessary

1. To prevent cheating
2. To prevent Wastage
3. To avoid error
4. To avoid over dose and under dose of medicine

(i)

Examples of endoparasites of cattle

1. Tapeworm
2. Liver Flukes
3. Round worm
4. Pin Worm

(ii)

Methods of controlling pest of cattle

1. Ensure proper sanitation in the farmhouse
2. Practice dipping on farm animals using appropriate pesticides
3. Ensure proper stocking density
4. Isolate / cull infested animal
5. Practice rotational grazing
6. Practice controlled burning of pasture
7. Dust with recommended pesticides

(i)

Formula mass of a compound is the sum of the atomic masses of constituent atoms in a compound.

(ii)

(i)

Ways by which humans could be protected from harmful effects of radioactivity

1. Minimize time of exposure
2. Move far away from source of radiation
3. By using protective clothing

(ii)

Uses of radioisotopes

1. For food preservation
2. For insect/pest Control
3. To improve crop
4. For equipment sterilization
5. Use as a fuel in nuclear reactor
6. Use to establish ages of various objects
7. Production of atomic bombs
8. Production of electricity

(i)

Alkanoates are products formed when an alkanol reacts with an alkanoic acid.

(ii)

Uses of alkanoates

1. Use as perfume, flavoring and essence
2. Use as solvent for paints
3. Use in the production of plastics/polymers
4. Use in making glycerol

(i)

Weathering is the disintegration and decomposition of rocks into smaller fragment of particles by chemical, physical and biological means.

(ii)

Ways of maintaining soil fertility on a sloppy land

1. Cover cropping
2. Strip Cropping
3. Terracing
4. Countour ploughing
5. Land rotation

(i)

Reasons why genetic variation is important in living organisms

1. Prevents extinction of species
2. Helps in disease resistance in organism
3. It ensures the survival of the species

(ii)

Examples of genetic variations in humans

1. Skin colour
2. Hair colour
3. Blood type
4. Baldness
5. Sickling
6. Dimples
7. Colour blindness
8. Albinism
9. Height
10. Rhesus factor

(i)

Archimedes principles states that a body wholly or partially immersed in a fluid experiences an upward force called upthrust which is equal to the weight of fluid displaced.

(ii)

Upthrust = Density x Volume x Acceleration due to gravity

Density = 10.30 kgm^-3

Volume = 200 m³

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

Upthrust = 10.30 kgm^-3 x 200 m³ x 10 ms^-2

Upthrust = 20,600 N