i)

Annual plants are plants which grow in one year/season during which they produce fruit and seeds and die off.

OR

Annual plants are plants that complete their life cycle in one season/one year.

ii)

Perennial plants are plants which continue to grow season after season producing fruits and seeds.

OR

Perennial plants are plants that complete their life cycle in more than two years.

i)

Danger involved in eating or drinking water in the laboratory

May result in the drinking of poisonous substances or eating contaminated foods.

ii)

Danger involved in washing hands with unknown liquid in a beaker

May result in burns/irritation/injury

iii)

Danger involved in walking barefooted

1. May result in slipping if there is water on the floor.

2. A person/One may get pricked with pieces of broken bottles/pins

3. A person/One may get burnt

i)

Digestive enzyme is a chemical/biological catalyst that help in breaking down food substances in the body

ii)

Examples of digestive enzymes in humans

1. Salivary amylase/Ptyalin
2. Pancreatic amylase
3. Maltase
4. Sucrase
5. Proteases/pepsin/rennin/trysin/erepsin/peptidase
6. Lipases

(i)

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

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{1}{4}$ + $\frac{1}{5}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{\mathrm{5\; x\; 1\; +\; 4\; x\; 1}}{20}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{\mathrm{5\; +\; 4}}{20}$

$\frac{1}{{\mathrm{R}}_{\mathrm{T}}}$ = $\frac{9}{20}$

Cross multiply.

R_T x 9 = 1 x 20

Divide both sides by 9

R_T = $\frac{20}{9}$ Ω or 2$\frac{2}{9}$ Ω or 2.2 Ω

Note: mark is deducted for answer without unit (Ω)

(ii)

Voltage (V) = Current (I) x Resistance (R)

Voltage (V) = 6V

Resistance (R) = $\frac{20}{9}$ Ω

6 = I x $\frac{20}{9}$

Multiply both sides by the denominator 9

6 x 9 = 20 x I

Divide both sides by 20

I = $\frac{\mathrm{6\; x\; 9}}{20}$ = $\frac{27}{10}$ = 2.7 A

Note: Mark is deducted for answer without or incorrect unit.

(i)

Distinction between organic fertilizer and inorganic fertilizer

Organic fertilizers are derived from natural sources/plants and animals whereas inorganic fertilizers are manufactured artificially from physical and chemical processes.

(ii)

Steps involved in preparing raised beds

1. Clearing of vegetation/weeds
2. Digging/loosening of top soil
3. Digging a path/furrow round the bed area
4. Breaking large lumps
5. Removing roots and stones
6. Shape the bed into size and firm the edges/Build the frame
7. Rake to level the surface of the bed
8. Water the bed

(i)

Function of the components of blod:

(ii)

Impact of organisms on humans:

(i)

Heredity is the process in which offsprings acquire characteristics from their parents through the genes they receive from them.

(ii)

Examples of heredity characters

1. Weight
2. Intelligence
3. Colour of the skin
4. Ability to roll the tongue
5. Temperature
6. Height/stature of an individual
7. Colour of eyes
8. Colour of hair
9. Blood group
10. Shape of face/nose/head/eye
11. Haemophilia
12. Albinism
13. Sex

(i)

Rusting

Chemical change because a new substance (rust) different from iron is formed.

(ii)

Burning

Chemical change because the ash cannot be turned back easily into the original material.

(iii)

Filtration

Physical change because the components can be gotten easily.

(iv)

Expansion of copper

Physical change because the original shape of the copper can be gotten easily.

(i)

Simple machine is a device that can be used to make work easier or faster.

OR

Simple machine is a device on which a force/an effort is applied at one point to overcome another force/load at another point.

OR

Simple machine is a device which enables a small force (effort) to overcome a large force (load).

(ii)

Types of simple machines

1. Levers
2. Inclined plane
3. Pulley
4. Wheel and axle
5. Screw
6. Wedge
7. Gears

(iii)

Why the efficiency of a machine cannot be equal to 100%

Part of the work put in the machine to overcome the load is used to overcome friction/weight of machine parts/force of gravity/air resistance so that the work output is always less than the work input.

(i)

In the depths of the ocean where it is always dark, there are no green plants

Light does not get to those depths and therefore photosynthesis cannot occur there.

(ii)

On an island where there are no insects and birds, the pawpaw plant produces only flowers but no fruits

Insects and birds transfer pollen grains for pollination of pawpaw flowers and in their absence fertilization does not occur and there is no fruit formation.

OR

Insects and birds are agents of pollination/transfer pollen grains. In their absence no fertilization and no fruit formation occur.

(i)

Laws of reflection

1. The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane
2. The angle of incidence is equal to the angle of reflection

(ii)

A labelled diagram to show the reflection of light on a plane mirror

(i)

Difference between self-pollination and cross-pollination

Self-pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower whereas cross-pollination is the transfer of pollen grains from the anther of a flower to the stigma of another flower on another plant of the same species.

(ii)

Agents of cross-pollination

1. Bees
2. Birds
3. Bats
4. Insects
5. Wind
6. Water/rain
7. Man

(i)

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

(ii)

How to test for carbon dioxide

1. Pass the gas through limewater
2. The colourless limewater turns milky/chalky when there is the presence of carbon dioxide

(iii)

Uses of carbon dioxide

1. Used in fruit preservation
2. Used in the manufacturing of soft drinks
3. Used as fire extinguisher
4. Used as refrigerant

iv)

Reasons

1. Presence of large/ single vacuole (IX)
2. Presence of cell wall (V)
3. Rectangular shape
4. Nucleus pushed to the side/periphery
5. Cytoplasm pushed to the side

v)

Differences between parts labelled I (Cell Membrane) and V (Cell Wall)

i)

(α) mass of irregular object (M) in I = 40 g
(β) Volume of water (V₁) in II = 40 cm³
(γ) Volume of water (V₂) in III = 60 cm³

ii)

Volume of the irregular object = 60 cm³ - 40 cm³ = 20 cm³

iii)

Density = $\frac{\mathrm{40\; g}}{\mathrm{20 }{\mathrm{cm}}^3}$ = 2 g/cm³ or 2 gcm^-3

iv)

Instruments for measuring mass of an irregular object

1. Beam balance
2. Top pan balance
3. Electronic balance

iv)

Precautions to be taken in performing the experiment

1. The object should be lowered gently into the water in the cylinder
2. Volume of the liquid should be read from the base of the meniscus or at the eye level
3. The measuring cylinder should be placed on a flat surface

i)

(α) chemical processes

II and III

(β) physical processes

I and IV

ii)

(α) Why chemical processes

1. The initial/original substance cannot be gotten back easily/irreversible
2. New substance formed
3. Change in mass
4. Accompanied by appreciable heat change

(β) Why physical processes

1. The initial/original substance can be gotten back easily/reversible
2. No new substance formed
3. No change in mass
4. Not accompanied by appreciable heat change

iii)

Examples of physical change

1. Expansion of metal on heating
2. dissolving sugar or salt in Water
3. Boiling of water
4. Melting of ice
5. Breaking/crushing of any Object

i)

ii)

Principles to consider when planning for rotational programme

1. Deep rooted crops should be followed by shallow rooted crops
2. Crops of the same family/class should not follow each other
3. Crops that use the same soil nutrients should not follow each other
4. Leguminous crops should be included in the cycle
5. A fallow period may be included in the crop rotation programme
6. Crops which attract the same diseases and pests should not follow each other

iii)

Reasons for selecting the crop named V (Soyabean)

1. Soyabean is a legume and therefore builds up soil fertility
2. Yam is a deep rooted crop and should be followed by soyabean which is a shallow rooted crop
3. Yam is a heavy feeder and must have taken good part of the nutrients
4. Yam and soyabean belong different classes of crops and therefore not likely to attract the same pests and diseases
5. Improves soil structure

iv)

Advantages of crop rotation

1. Increases soil fertility
2. Enhances soil structure
3. Prevents soil erosion
4. Improves soil nutrients and nutrient uptake regulation
5. Controls the spread of pests and diseases
6. Controls weed easily
7. There is effective use of the land
8. Harvest of different types of crops on the same piece of land