(i)

Structure of the mammalian heart

(ii)

Position of the heart

Located between the lungs in the thoracic cavity, slightly towards the left of the sternum (breastbone).

Functions of the heart

1. Pumps blood throughout the body
2. Delivers oxygen, hormones, glucose and other components to various parts of the body, including the human heart.
3. Ensures that adequate blood pressure is maintained in the body

(iii)

Parts of the human heart

I → Pulmonary Artery
II → Pulmonary Vein III → Left Atrium
IV → Semilunar Valves
V → Left Ventricle
VI → Septum
VII → Right Ventricle
VIII → Atrioventricular Valves
IX → Right Atrium
X → Aorta

(iv)

(v)

Because V (left ventricle) has to pump blood all over the body whereas VII (right ventricle) only pumps blood to the lungs. (Thicker walls helps V to exert pressure to force blood all over the body)

(i)

A → Artery
B → Vein
C → Capillary

(ii)

Parts of the blood vessels

I → Outer coat
II → Lumen
III → Muscle and elastic tissue

(iii)

Functions of the blood vessels

(iv)

Differences between blood vessels

(i)

I → Effort
II → Load
III → Pivot/Fulcrum

(ii)

First class lever (Pivot between the effort and the load)

Note: if you forget the positions, use the acronym PLE, the last three letters of the word PEOPLE

First class → Pivot (P) is at the middle
Second class → Load (L) is at the middle
Third class → Effort (E) is at the middle

(iii)

Examples of first class levers

1. Pliers
2. Scissors
3 . A crow bar
4. A claw hammer
5. A see-saw
6. A weighing balance/beam balance

(iv)

II (Load) Distance = Length of the rigid bar - I (Effort) Distance

II (Load) Distance = 100 cm - 80 cm

II (Load) Distance = 20 cm

(v)

Mechanical advantage (M.A) = $\frac{\mathrm{Effort\; arm/distance}}{\mathrm{Load\; arm/distance}}$

Mechanical advantage (M.A) = $\frac{\mathrm{80\; cm}}{\mathrm{20\; cm}}$

Mechanical advantage (M.A) = 4

(i)

(ii)

II → experiment to show that some part of air is used in burning
III → experiment to show that expired air contains carbon dioxide

(iii)

Reducing/simple sugar/glucose

(i)

Ways in which mulching helps to conserve the soil

1. It checks growth of weeds (which will otherwise take water out of the soil)
2. It improves soil structure/texture (which in turn improve the soil water 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. dry 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 (or presence) of harmful substances/radiations into the environment.

(ii)

Major atmospheric pollutants

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

(i)

Ways in which legumes are important 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)

Qualitites of a good thermometric liquid

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

(ii)

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

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

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)

Names of 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)

Ways in which earmuffs are important

1. Protects the ear against noise of high frequency
2. To keep a person's ear warm in a cold environment
3. Protect the ear against hearing loss
4. Prevent dust from entering the ear

i)

Stages of water treatment for public consumption

Screening → aeration → sedimentation → sand filtration → chlorination

ii)

Significance of stages in water treatment

i)

ii)

i)

Differences between hypogeal germination and epigeal germination

ii)

i)

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

ii)

Resistors in series

R = R₁ + R₂

R = 2 + 2 = 4 Ω

Resistors in parallel

$\frac{1}{\mathrm{R}}$ = $\frac{1}{{\mathrm{R}}_1}$ + $\frac{1}{{\mathrm{R}}_2}$

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

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

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

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

Cross multiply

R x 7 = 1 x 12

7R = 12

Divide both sides by 7

R = $\frac{12}{7}$ Ω = 1.71 Ω

i)

Differences between compounds and mixtures

ii)

Ways through which AIDS is transmitted

1. Sexual intercourse
2. Blood transmission
3. Infected mother to foetus during birth
4. Injection with infected needles
5. Blood to blood contact with an infected person

i)

A shadow is the image formed of an object which lies in the path of light.

ii)

Types of shadows

1. Umbra/total shadow
2. Penumbra/partial shadow

iii)

i)

A reflex action is an involuntary or instantaneous movement or response to an external stimulus.

ii)

iii)

Sense organs and their function

i)

A hormone is a chemical substance produced by special endocrine/ductless glands in the body to enable certain organs function properly.

ii)

Copy and complete the following table

i)

Convection is the transfer of heat in a fluid through the rising of hot particles and the sinking of cooler particles.

ii)

Why convection cannot take place in solids

1. Particles in a solid occupy fixed positions/do not move from a point to another
2. They only vibrate about a mean position
3. They are therefore incapable of carrying heat from one point to another

i)

C and D

ii)

A and B

iii)

B and E

i)

Differences between red blood cells and white blood cells

ii)

Expected changes that will occur in the composition of the blood leaving a muscle of a person soon after a period of vigorous activity

1. There is increase in carbon dioxide
2. There is decrease in oxygen
3. There is decrease in glucose

i)

ii)

Methods of softening hard water

1. Addition of washing soda/sodium carbonate (Na₂CO₃)
2. Boiling
3. Distillation
4. Use of ion exchange resin/Deionization

iii)