(i)

Functions of vitreous humour of the eye

1. It helps to maintain pressure in the eyeball/maintain shape of eyeball
2. It helps to refract light passing through the eyeball or allow light to pass through
3. It contains phagocytes (which keeps the visuals axis clear most of the time)
4. It helps to keep retina in place (by pressing against the choroid)
5. Medications are sometimes injected into the vitreous (where it lasts for longer period of time)
6. It keeps free radicals from damaging the lens

(ii)

Function of hammer of the ear

It vibrates/transmits impulse (when hit by the eardrum)

(iii)

Function of fovea of the eye

It provides the clearest vision on the retina/contains cones for clear vision

(iv)

Function of organ of the corti of the ear

It converts sound vibrations into nerve impulses

(v)

Function of cochlea of the ear

It transforms vibrations of liquids in it and associated structures into neural signal/sending signal to the brain

(i)

Differences between compounds and mixtures

(ii)

146C → 147N + 0-1e

(i)

Resistance of a conductor is the opposition offered to electric current (or flow of charges).

(ii)

The 2Ωs are in series.

R_{series total} = 2Ω + 2Ω = 4Ω

The R_{series total} (4Ω) is parallel to the 3Ω

$\frac{1}{{\mathrm{R}}_{\mathrm{total}}}$ = $\frac{1}{4}$ + $\frac{1}{3}$

$\frac{1}{{\mathrm{R}}_{\mathrm{total}}}$ = $\frac{\mathrm{3\; x\; 1\; +\; 4\; x\; 1}}{12}$

$\frac{1}{{\mathrm{R}}_{\mathrm{total}}}$ = $\frac{\mathrm{3\; +\; 4}}{12}$

$\frac{1}{{\mathrm{R}}_{\mathrm{total}}}$ = $\frac{7}{12}$

Cross multiply

7 x R_total = 12 x 1

Divide both sides by 7

R_total = $\frac{12}{7}$Ω = 1.71Ω

(i)

Oestrus is the period within the breeding/reproductive cycle of a female farm animal when it comes on heat/is ready to accept a male for mating.

(ii)

(i)

Characteristics of ionic compounds

1. They are solid at room temperature
2. They have high boiling point
3. They have high density
4. They are generally soluble in polar solvents/water
5. They conduct electricity in molten state/in aqueous solution
6. They have high melting point
7. They exist in crystalline form

(ii)

Why helium does not form a compound

1. Helium is an element with completely filled valence shell/it is stable/has maximum of 2 electrons in its shell
2. It therefore does not require transfer (or acceptance or sharing) of valence electrons for stability

(i)

Industrial waste is solid (or semi-solid or liquid or gaseous) unwanted material from industrial processes or activity.

(ii)

Ways by which industrial waste could be useful

1. Through recycling
2. Recovering waste for re-use
3. Turning industrial waste into manure
4. Channeling waste watr for agricultural use
5. Treating biomass to become biogas for energy
6. Using husks for making door mats
7. Using watr sachets in making bags
8. Using cocoa husks for making soap
9. Generate income

(i)

Soil fertility refers to a soil that contains the needed crop nutrients (in right quantities) for propere crop growth.

OR

Soil fertility is the ability of the soil to support effctive crop growth.

(ii)

Distinction between major nutrients and minor nutrients

Major nutrients are food/chemical substances needed by crops in large quantities whereas minor nutrients are those food/chemical substances needed in small quantities by crops.

(i)

Distinction between distance and displacement

(ii)

Change the speed from km/h to m/s which is the S.I unit for speed.

Speed = 250 km/h = $\frac{\mathrm{250\; x\; 1000\; m}}{\mathrm{1\; x\; 60\; x\; 60}}$ = 69.4 m/s

Time = $\frac{\mathrm{Distance}}{\mathrm{Speed}}$

Time = $\frac{10000}{69.4}$ = 144s

(i)

(ii)

Uses of transistors

1. Used for amplification of signals/impulses/amplifier
2. Used as a switch

(i)

Poultry refers to all domestic birds which are kept for the primary purpose of producing meat or eggs.

(ii)

Advantages of exotic breed of birds over local breed

1. Exotic breed of birds are larger in size than local breeds
2. Exotic breed of birds lay bigger eggs than local breeds
3. Exotic breed of birds lay more eggs than local breeds
4. Exotic breed of birds grow faster than local breeds
5. Exotic breed of birds have tender meat than local breeds

(i)

Experiment to show that expired air contains water

1. Expired air is passed unto cobalt chloride paper/anhydrous CuSO<sub>4
2. The cobalt chloride paper turns pink (or anhydrous CuSO4 turns blue)
3. This confirms the presence of water in expired air</sub>

(ii)

(i)

NaHCO₃ → Sodium hydrogen trioxocarbonate (IV)

(ii)

Fe₂O₃ → Iron (III) oxide

(iii)

CCl₄ → tetrachloromethane

(iv)

CH₃CH₂CH=CHCH₃ → 2-pentene/pent-2-ene

(i)

The law of floatation states that a floating body displaces its own weight of the fluid in which it floats.

(ii)

Characteristics of the image formed by a plane mirror

The image formed by a plane mirror is:

1. upright/erect
2. at equal distance from the mirror as the object
3. virtual/behind the mirror
4. Laterally inverted
5. Equal in size as the object

(i)

Reason for providing feed and water in clean containers

To avoid contamination

(ii)

Reason for ensuring a routine deworming programme

To prevent worm infestation

(iii)

Reason for practicing rotational grazing

To prevent pest build-up/break the cycle of pest infestation

(iv)

Reasons for avoiding overstocking of animals

1. To prevent fighting or cannibalism
2. To ensure proper spacing
3. To avoid spread of diseases
4. To ensure proper ventilation

(v)

Reasons for preventing sheep from feeding on wet pastures

1. To prevent diarrhoea
2. To prevent infestation by worms

(i)

Water and sodium

2Na + 2H₂O → 2NaOH + H₂

(ii)

Water and magnesium

Mg + 2H₂O → Mg(OH)₂ + H₂

OR

Mg + H₂O → MgO + H₂

(i)

Glomerular filtrate is the fluid in the lumen of the Bowman's capsule of the nephron that has been filtered from the capillaries of the glomerulus.

(ii)

Causes of fibroid in the human reproductive system

1. Hormonal/oestrogen dependent/birth control pill
2. Genetic/family history
3. Consumption of red meat/alcohol/caffeine
4. Pregnancy
5. Overweight
6. Not eating enough fruits
7. Early menarche
8. Vitamin D deficiency
9. Use of hair relaxers
10. Severe stress

(i)

Sodium hydroxide = NaOH

Mass = 4g

Molar Mass = 23 + 16 + 1 = 40 g mol^-1

Volume = 250 cm³ = $\frac{250}{1000}$ dm³ = 0.25 dm³

Molarity = $\frac{4}{\mathrm{40\; x\; 0.25}}$ = 0.4 mol/dm³ or 0.4 mol dm^-3

(ii)

The mole doesn't change despite the change in volume.

The initial mole = final mole

Mole = Concentration x Volume

C₁V₁ = C₂V₂

C₁ = 0.4 mol dm^-3

V₁ = 100 cm³

C₂ = 0.25 mol dm^-3

0.4 mol dm^-3 x 100 cm³ = 0.25 mol dm^-3 x V₂

Divide both sides by 0.25 mol dm^-3

V₂ = $\frac{\mathrm{0.4\; x\; 100}}{0.25}$ = 160 cm³

Volume of water required for dilution = Final volume - Initial volume

Volume of water required for dilution = V₂ - V₁

Volume of water required for dilution = 160 cm³ - 100 cm³

Volume of water required for dilution = 60 cm³

(i)

Magnetic field is a region around a magnet where magnetic force is experienced.

(ii)

Properties of magnetic lines of force

1. They are imaginary
2. They always start and end on opposite poles
3. They indicate the direction of the magnetic force
4. They do not cross each other

(iii)

(i)

Flushing is a process of feeding whereby a female animal is placed on a high level of nutrition for about two weeks before servicing/crossing it.

(ii)

Reasons for flushing the ewe during breeding

1. To help the animal store enough energy for the developing foetus
2. To increase the chances of twins/multiple births
3. To enable healthy birth
4. To increase the chances of pregnancy

(i)

Rusting is the chemical process in which iron or products of iron are oxidised to hydrated iron (III) oxide in the presence of water and oxygen/air.

(ii)

Methods of preventing rusting

1. Oiling/greasing
2. Painting
3. Zinc coating/plating/galvanising
4. Tin coating/plating
5. Cathodic protection
6. Alloying

(i)

Ways of controlling pests on a maize farm

1. Use of traps
2. Use of scare crows
3. Good farm sanitation/weeding farm regularly
4. Use of pesticides or insecticides
5. Biological method
6. Early harvesting
7. Early planting
8. Crop rotation
9. Fencing
10. Picking

(ii)

Importance of mulching

1. Mulching helps cool the soil/controls soil temperature
2. It helps reduce soil erosion
3. It improves soil structure/compactibility
4. It adds humus to the soil when organic material is used
5. It helps in conserving soil water/keeps the soil moist

(i)

Qualities of a good thermometric fluid

1. It must be a good thermal conductor
2. It must be easily seen in the tube/coloured/opaque
3. It must have a wide temperature range
4. It must not wet glass
5. It must not vapourise
6. It must expand uniformly

(ii)

Examples of a liquid-in-glass thermometer

1. Clinical thermometer
2. Laboratory thermometer
3. Max and min thermometer

(iii)

Precautions to be taken when using a liquid-in-glass thermometer

1. The thermometer must be sterilised in an antiseptic
2. Bulb must be inserted well into the substance
3. Reading must be taken at eye level
4. Bulb must not touch the container
5. Reset thermometer after each use