(i)

Diffusion is the process whereby molecules/particles of a liquid/gas move from a region of higher concentration to a region of a lower concentration until they are uniformly spread throughout an occupied space.

(ii)

Surface tension is the property of a liquid which makes the surface behave as if it were stretched elastic skin.

(iii)

Capillarity is the rise or fall of liquids in small/narrow tubes/columns as a result of adhesion and surface tension forces.

(i)

Composition of blood

1. Serum/plasma
2. Red blood cells
3. White blood cells
4. Platelets

(ii)

Functions of blood

1. It transports oxygen from the lungs to the tissues
2. It transports/distributes/carries digested food substances to the tissues
3. It transports excretory materials/it carries carbon dioxide (CO₂) or nitrogenous waste from the tissues to the lungs
4. It protects the body against diseases/produces antibodies
5. It forms clot to prevent loss of blood/excessive bleeding
6. It transports hormones
7. It regulates body temperature
8. It maintains the turgidity of cells in the body
9. It prevents entry of germs into the body through a wound

(i)

1. Ions are formed when an atom gains or loses an electron
2. When an atom gains an electron, the number of electrons becomes greater than the number of protons and so a negative ion (Anion) is formed
3. When an atom loses an electron, the number of protons becomes greater than the number of electrons and so a positive ion (Cation) is formed

(ii)

Differences between a proton and an electron

(iii)

Chemical symbols

i)

Uses of water in agriculture

1. Cleaning
2. Irrigation
3. Fishing/Fish farming
4. For fertilizer application
5. For pest control
6. Drinking/consumption by farm animals

ii)

Deep rooted crops

1. Tomato
2. Carrots
3. Yam
4. Cassava
5. Watermelon
6. Cocoyam
7. Pumpkin

i)

Circulatory system is a collection of tissues and organs which transports materials or food or water or oxygen throughout the (whole) body

ii)

i)

Mass is the amount of substance (matter) in a body or particle

Is a measure of how much matter is in an object

ii)

Density = Mass / Volume

Mass = Density x Volume

Density = 2.0 g cm^-3, Length = 3 cm

Length of a cuboid (Equal size) = Length x Length x Length

Volume of the box = 3 cm x 3 cm x 3 cm = 27.0 cm³

Mass = 2.0 g cm^-3 x 27.0 cm³ = 54.0 g

i)

ash → solid

ii)

carbon dioxide → gas

(i)

1. The level of water decreases and the level of the red liquid rises
2. Red liquid moves/diffuses into the water

(ii)

1. Water is at a higher potential/level/pressure so it moves in the direction of lower potential/level/pressure
2. Molecules of red liquid at a higher concentration moves towards region of lower concentration/molecules of red liquid diffuse into the water

(iii)

1. The level of the liquids will be the same/motion of the liquids stop (greater than 10 cm but lower than 30 cm) because the same pressure will be exerted by the liquids in A and B
2. The colour of the liquid in A and B will be uniform/same (pale/light red) because the concentration will be the same

(i)

a → ammonia gas
b → gas jar
c → round bottomed flask

(ii)

The meaning of the arrow sign d is heating

(iii)

The calcium oxide dries the gas produced

(iv)

c is tilted downwards to prevent condensed water from falling back into the hot flask/to cause cracking

(v)

Upward delivery/downward displacement of air

(vi)

Test for the ammonia gas

Damp/moist red litmus paper turns blue in the presence of the (ammonia) gas

OR

Gas produces fumes with HCl vapour/concentrated hydrochloric acid

OR

Gas has pungent/choky/urinal smell

(vii)

1. Calcium hydroxide (Ca(OH)₂)/Sodium hydroxide (NaOH)

2. Ammonium chloride/Ammonium salt (NH₄Cl)

(i)

I → to kill cells/stop photosynthetic process
II → to remove green pigment/decolourized
III → to wash off the alcohol/to soften the leaf

(ii)

The green part turns blue-black because photosynthesis took place in the green part to produce starch

(iii)

The other (yellow) part of the leaf not change colour because it does not contain chlorophyll/green pigment which will trap sunlight for photosynthesis to occur

(iv)

Presence of chlorophyll/green pigment in leaf is required/necessary for photosynthesis/production of starch to take place/occur

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)

Negative charged particles

1. Anion/negative ion
2. Electron
3. Beta particle

(ii)

Positive charged particles

1. Cation/positive ion
2. Proton
3. Alpha particle

(iii)

Particles with no charge

1. Atom
2. Neutron
3. Molecule

(i)

Work input = Effort x Effort distance

Work input = 25 N x 4 m = 100 J

(ii)

Work output = Load x Load distance

Work output = 20 N x 2 m = 40 J

(iii)

Efficiency of the machine = $\frac{\mathrm{Work\; out}}{\mathrm{Work\; input}}$ x 100%

Efficiency of the machine = $\frac{\mathrm{40\; J}}{\mathrm{100\; J}}$ x 100% = 40%

OR

Efficiency of the machine = $\frac{\mathrm{Mechanical\; Advantage\; (M.A)}}{\mathrm{Velocity\; Ratio\; (V.R)}}$ x 100%

Mechanical Advantage = $\frac{\mathrm{Load}}{\mathrm{Effort}}$ = $\frac{20}{25}$ = $\frac{4}{5}$

Velocity Ratio = $\frac{\mathrm{Effort\; Distance}}{\mathrm{Load\; Distance}}$ = $\frac{4}{2}$

Efficiency of the machine = $\frac{\frac{4}{5}}{\frac{4}{2}}$ x 100%

Efficiency of the machine = $\frac{4}{5}$ ÷ $\frac{4}{2}$ x 100%

Reciprocate the fraction after the ÷ and change the ÷ to multiplication (x)

Note: reciprocate means the numerator becomes the denominator and the denominator becomes the numerator.

Efficiency of the machine = $\frac{4}{5}$ x $\frac{2}{4}$ x 100%

Efficiency of the machine = $\frac{\mathrm{4\; x\; 2}}{\mathrm{5\; x\; 4}}$x 100%

Note: the 4s cancel each other.

Efficiency of the machine = $\frac{2}{5}$x 100%

Note: 5 divides itself 1 time and 100, 20 times.

Efficiency of the machine = 2 x 20% = 40%

(i)

Balanced diet is a diet that contains all the essential food nutrients in the right proportions.

(ii)

Classes of food which should be present in a balanced diet

1. Carbohydrates
2. Proteins
3. Fats and oils
4. Vitamins

(iii)

Protein helps to build and repair the worn out tissues in the body

Carbohydrate gives the body the energy it needs

Fats and oils provide energy for the body

Vitamins protect the body from diseases

(i)

How ions are formed from atoms

1. Ions are formed when an atom gains or loses an electron
2. When an atom gains an electron, the number of electrons becomes greater than the number of protons and so a negative ion (Anion) is formed
3. When an atom loses an electron, the number of protons becomes greater than the number of electrons and so a positive ion (Cation) is formed

(ii)

Differences between a proton and an electron