(i)

(ii)

Differences between an element and a compound

(i)

Greenhouse effect is the trapping of infrared radiations in the earth's surface by gases/carbon dioxide/substances making the earth warmer.

(ii)

Climate change is a large scale or long term/changes in the earth's weather patterns/average temperature.

(i)

Electrical rectification is the conversion of alternating current to direct current.

(ii)

The alternating current is made to pass through a diode, the diode allows the only one half of the alternating current which is in one direction to pass through it.

(i)

Rainfall

1. For seed germination
2. For cooling plants/soil
3. For dissolving mineral salts for absorption

(ii)

Temperature

1. For seed germination
2. For drying of seeds

(iii)

Sunshine

1. For photosynthesis
2. For drying seeds

(iv)

Wind

1. For pollination
2. For seed dispersal

(i)

Reasons why goats are not normally kept under the intensive system of management.

1. Goats are normally very aggressive
2. Their growth rate reduces when they are confined
3. They are highly selective in feeding
4. To increase resistance to diseases (due to exercise)

(ii)

Diseases that affect rabbits

1. Coccidiosis
2. Mange/ear canker
3. Warbles
4. Calici virus
5. Common diarrhoea
6. Cold
7. Snuffles
8. Hairballs
9. Uterine tumours/cancer
10. myxomatosis

(i)

Note:
1. + means Na has lost 1 electron
2. Number of electrons = 11 - 1 = 10

(ii)

Differences between organic compounds and inorganic compounds

(i)

Decomposers are organisms that feed/depend on dead organic materials and thereby aid the decay process of those materials.

OR

Decomposers are organisms that break down/decompose/cause decay of dead organisms.

(ii)

Common decomposers in an ecosystem

1. Bacteria
2. Fungi
3. Earthworm
4. Any saprophyte
5. Millipede
6. Termite

(i)

Structures in the middle ear that help in the transmission of sound waves

1. Malleus/hammer
2. Incus/anvil
3. Stapes/stirrup
4. Ossicles/ear bones

(ii)

Importance of earmuffs

1. It protects the ear against noise of high frequency
2. It keeps a person's ear warm in a cold environment
3. It protects the ear against hearing loss
4. It prevents dust from entering the ear

(i)

Power = IV
where I = current and V = voltage

Current = $\frac{\mathrm{Power}}{\mathrm{Voltage}}$

Power = 1.5 kW = 1.5 x 10³ W = 1500 W

Voltage = 240 V

Current = $\frac{\mathrm{1500\; W}}{\mathrm{240\; V}}$ = 6.25 A

(ii)

Power = $\frac{\mathrm{Work\; done/Energy}}{\mathrm{Time}}$

Energy = Power x Time

Method I

Energy in kW h

Energy = 1.5 kW x 2 h = 3 kW h

Method I

Energy in Joules (J)

Note: the SI unit of time is seconds (s) hence convert the hours to seconds.

Time = 2 x 60 x 60 s = 7200 s

Energy = 1500 W x 7200 s = 1.08 x 10⁷ J

(i)

Importance of mulching

1. It checks growth of weeds (which will otherwise take water out of the soil)
2. It improves soil structure/texture (which in turn improves the soil waters holding capacity/soil drainage)
3. It reduces soil erosion
4. It reduces water loss from the soil (by holding available moisture in the root zone)
5. It adds nutrients to the soil
6. It helps maintain soil temperature

(ii)

Examples of mulching materials

1. Gry grass/grass
2. Banana leaves/plantain leaves/leaves
3. Ground corn cob
4. Palm fronds
5. Polythene materials
6. Organic manure
7. Wood shavings/dust/bark
8. Straw

(i)

Pollution is the release/presence of harmful substances/radiations into the environment.

(ii)

Major atmospheric pollutants

1. Chlorofluorocarbons/CFCs
2. Sulphur oxide/SO₂/SO₃
3. Nitrogen oxide/NO₂/N₂O₅
4. Lead (II) oxide/PbO
5. Carbon monoxide/CO
6. Smoke/fumes from industries or cars
7. Dust

(i)

(ii)

Sources of potassium

1. Fruits/bananas/oranges/pineapples
2. Vegetables/carrots/potatoes/cucumbers
3. Spinach
4. Mushroom
5. Peas/beans

Sources of calcium

1. Dairy products/milk/cheese/yoghurt
2. Green leafy vegetables/legumes/cabbage
3. Salmon/sardine
4. Sunflower seeds
5. Nuts
6. Bones
7. Bread

(i)

Method of preparation of a salts:

(ii)

Pb(NO₃)₂ + 2NaCl → PbCl₂ + 2NaNO₃

(i)

Tidal waves are wave-like swellings of the ocean/water/ surface caused by the effect of gravitational interaction between the moon, sun and the earth.

(ii)

Ways in which water could be contaminated

1. Oil spillage
2. Domestic waste/sewage discharge into water bodies
3. Discharge of industrial waste into water bodies/waste from mining industries
4. Waste from hospitals
5. E-waste/radioactive waste into underground water
6. Excess inorganic fertilizers washed into water bodies
7. Excess insecticides/herbicides into water bodies
8. Petroleum products/gasoline/diesel into water bodies
9. Run-off/silt from construction sites
10. Chemicals/DDT used in fishing
11. Animals stepping into water bodies/drinking
12. Putting dirty hands into water

(i)

Importance of legumes in crop production

1. It fixes nitrogen to enrich the soil
2. It maintains the fertility of the soil
3. It adds organic matter to the soil
4. It checks soil erosion

(ii)

Advantages of crop rotation

1. It helps to improve soil fertility
2. It controls pest
3. It controls diseases
4. It ensures economic use of land
5. It checks soil erosion

(i)

Qualities of a good thermometric liquid

1. It must be a good thermal conductor
2. It must be easily seen in the tube
3. It must have a wide temperature range between its transition temperatures
4. It must not wet glass
5. It must not vapourize/condense in the tubing
6. It must have uniform/regular expansion

(ii)

Precautions that must be taken when using a liquid-in-glass thermometer

1. It must be sterilized in an antiseptic
2. The bulb must have to be inserted well into the substance
3. Reading must be taken at eye-level
4. The bulb must not touch the sides or bottom of the container
5. Allow sufficient time for thermal equilibrium to be reached

(i)

Functions of the placenta in mammals

1. Facilitate exchange of materials between mother and foetus/foetus obtains nourishment through the placenta/waste materials pass out through the placenta
2. Secretes hormones/oestrogen/progesterone
3. Attaches the foetus to the uterine wall

(ii)

Structural features of the placenta which adapt the placenta to its functions

1. Rich in blood vessels
2. Thin walled
3. Large surface area

(i)

816   O, 817    O

They both have 8 protons.

816   O has 16 - 8 = 8 neutrons

817    O has 17 - 8 = 9 neutrons

(ii)

612   C, 614    C

They both have 6 protons.

612   C has 12 - 6 = 6 neutrons

614    C has 14 - 6 = 8 neutrons

(i)

Order of stages of water treatment for public consumption

Screening → aeration → sedimentation → sand filtration → chlorination

(ii)

Significance of stages in water treatment

(i)

Mechanical advantage is the ratio of work output to the work input or ratio of load to effort.

OR

Mechanical Advantage (M.A) = $\frac{\mathrm{Load\; (L)}}{\mathrm{Effort\; (E)}}$

(ii)

Examples of second class levers

1. Wheelbarrow
2. Bottle top opener
3. Nut cracker
4. Nail clipper/cutter
5. Paper cutter
6. Stapler

(i)

Apparatuses needed in the preparation of a standard solution

1. Volumetric flask
2. Beaker
3. Funnel
4. Stirrer
5. Chemical balance
6. Spatula
7. Wash bottle
8. Dropper

(ii)

Concentration/Molarity = $\frac{\mathrm{Mole}}{\mathrm{Volume}}$

Mole = Concentration/Molarity x Volume.

The value of the mole is constant even after dilution.

M₁ x V₁ = M₂ x V₂

V₂ = $\frac{{\mathrm{M}}_{1}x{\mathrm{V}}_1}{{\mathrm{M}}_2}$

M₁ = 5 M

V₁ = 20 cm³

M₂ = 1 M

V₂ = $\frac{\mathrm{5\; M}x20{\mathrm{cm}}^3}{\mathrm{1\; M}}$ = 100 cm³

Volume of water needed = V₂ - V₁

Volume of water needed = 100 cm³ - 20 cm³

Volume of water needed = 80 cm³

(i)

Differences between hypogeal germination and epigeal germination

(ii)

(i)

(ii)

(i)

Mode of cultivation in terms of method of propagation

A → stem cutting
B → setts/yam seed/small tubers/whole tuber/tuber bulb/tissue culture

(ii)

Mode of cultivation in terms of land preparation

Product A

1. Clearing and burning of land/stumping
2. Ploughing and harrowing
3. Ridging and mound/heap making
4. Manure/ fertilizer application

Product B

1. Clearing and burning of land/stumping
2. Ploughing and harrowing
3. Ridging and mound/heap making
4. Manure/ fertilizer application
5. Tilling

(iii)

Mode of cultivation in terms of plant distance

Product A

(90 cm -100 cm) × (100 cm – 150 cm)/ (0.9 m - 1.0 m) × (1 m – 1.5 m)

OR

60 cm × 60 cm (on ridges)
75 cm × 150 cm (flat ground)
78 cm × 120 cm (monocrop)
120 cm × 120 cm (intercrop with maize)

Product B

(100 cm -120 cm) × (100 cm – 120 cm)/ (1.0 m - 1.2 m) × (1.0 m – 1.2 m)

OR

90 cm apart on mounds (staggered in alternate rows)

(i)

Use of dropping pipette

To transfer small amount of liquid/transfer liquid drop by drop.

(ii)

Use of test tube

To hold/mix/heat chemicals in experiments/reaction

(iii)

Use of gloves

For protection from contact with harmful substances/for holding hot objects/protective barrier against germs/ bacteria

(iv)

Use of reagent bottle

To hold/store chemicals in liquid or powder form/for mixing chemicals

(v)

Use of goggles

To protect eye and its surrounding areas from particles/water/chemical/radiations

(i)

NH_{3 gas is brought near HCl vapour}

There is formation of white fumes.

(ii)

Red litmus paper is put in orange juice

There is no change in colour of litmus paper/colour of litmus paper remains the same

(iii)

Red litmus paper is put in dettol

Colour of litmus paper changes to blue.

(iv)

Blue litmus paper is put in baking powder

There is no change in colour of litmus paper/colour of litmus paper remains the same.

(i)

Instruments to determine accurate volumes of liquids

1. Pipette
2. Burette
3. Graduated/measuring cylinder
4. Volumetric/graduated flask
5. Graduated beaker

(ii)

Instruments to determine mass of a substance

1. Electronic balance
2. Chemical balance
3. Top-pan balance
4. Lever balance
5. Beam balance