Question 1
(a) Fig. 1.1 is a diagram of the human gas exchange system. (Sub-topic – B11.1)
(i) Identify the parts labelled A and B in Fig. 1.1.
▶️Answer/Explanation
A: Rib
B: Diaphragm
(ii) List three structures inspired air passes through on its way to the alveoli.
▶️Answer/Explanation
1: Nose/Mouth
2: Trachea
3: Bronchus/Bronchioles
(iii) Place a tick (✓) in the box to show the blood vessel that brings blood to the lungs.
▶️Answer/Explanation
Pulmonary Artery
(b) Expired air contains a higher percentage of carbon dioxide than inspired air. (Sub-topic – B11.1)
(i) State one other way that the composition of expired air is different from inspired air.
▶️Answer/Explanation
Expired air contains less oxygen or more water vapor than inspired air.
(ii) State the test for carbon dioxide gas and give the observation for a positive result.
▶️Answer/Explanation
Test: Limewater
Observation: Limewater turns cloudy/milky.
(c) A student records their breathing rate while walking and while running. The results are shown in Fig. 1.2. (Sub-topic – B11.1)
(i) State the breathing rate of the student while walking.
▶️Answer/Explanation
20 breaths per minute
(ii) The student repeats the investigation and records the breathing rate while at rest. Describe the expected changes to the pattern of breathing while at rest when compared to running.
▶️Answer/Explanation
The breathing rate will decrease, and the depth of breathing will also decrease when at rest compared to running.
Question 2 (Sub-topic – C8.3)
(a) Table 2.1 shows information about three Group VII elements.
Table 2.1
| Element | Formula | Colour | Physical state at 20 °C |
|---|---|---|---|
| Chlorine | Cl2 | Gas | |
| Bromine | Orange | ||
| Iodine | I2 | Grey |
(i) Complete Table 2.1.
▶️Answer/Explanation
| Element | Formula | Colour | Physical state at 20 °C |
|---|---|---|---|
| Chlorine | Cl2 | Pale green | Gas |
| Bromine | Br2 | Orange | Liquid |
| Iodine | I2 | Grey | Solid |
(ii) State the name given to the Group VII elements in the Periodic Table.
▶️Answer/Explanation
Halogens
(b) Bromine reacts with hydrogen to make hydrogen bromide. Construct the word equation for this reaction.
▶️Answer/Explanation
Hydrogen + Bromine → Hydrogen bromide
(c) Aqueous bromine is orange. Predict the colour change, if any, when aqueous bromine is mixed with ethene gas. Explain your answer.
▶️Answer/Explanation
Colour change: Orange to colourless
Explanation: Ethene is an unsaturated hydrocarbon with a double bond, which reacts with bromine, causing the orange colour of bromine to disappear as it forms a colourless dibromoethane.
(d) An aqueous solution is tested to see if bromide ions are present. State the test for aqueous bromide ions and give the observation for a positive result.
▶️Answer/Explanation
Test: Add aqueous silver nitrate to the solution.
Observation: A cream-coloured precipitate forms.
(e) Fig. 2.1 shows the electrolysis of molten lead(II) bromide using inert electrodes.
Identify the substances formed at the cathode and the anode.
▶️Answer/Explanation
At cathode: Lead
At anode: Bromine
Question 3
(a) A cyclist starts from rest and accelerates for 20 s. The cyclist then travels at a constant speed of 5 m/s for 90 s. Finally, the cyclist slows down and stops after a further 5 s. (Sub-topic – P1.2)
(i) On the grid in Fig. 3.1, draw a speed-time graph for the cyclist’s journey.
▶️Answer/Explanation
The speed-time graph should have three sections:
- From 0 to 20 seconds: A straight line rising from (0, 0) to (20, 5) m/s, representing constant acceleration.
- From 20 to 110 seconds: A horizontal line at 5 m/s, representing constant speed.
- From 110 to 115 seconds: A straight line falling from (110, 5) to (115, 0) m/s, representing constant deceleration.
(ii) Calculate the distance travelled when the cyclist is travelling at constant speed.
▶️Answer/Explanation
Distance = Speed × Time
Speed = 5 m/s
Time = 90 s
Distance = 5 m/s × 90 s = 450 m
(b) Energy from the Sun heats the black saddle of the bicycle.
(i) State the method of energy transfer between the Sun and the Earth. (Sub-topic – P2.3)
▶️Answer/Explanation
The method of energy transfer between the Sun and the Earth is radiation.
(ii) Name the part of the Sun’s electromagnetic spectrum that is responsible for heating the saddle. (Sub-topic – P3.3)
▶️Answer/Explanation
The part of the Sun’s electromagnetic spectrum responsible for heating the saddle is infrared.
(iii) The Sun also heats up the air in the bicycle tyres. This causes the pressure of the air in the tyres to increase. Describe, in terms of the motion of the air molecules, why the pressure of the air in the tyres increases as the temperature of the air increases. (Sub-topic – P2.1)
▶️Answer/Explanation
As the temperature of the air increases, the kinetic energy of the air molecules increases. This causes the molecules to move faster and collide more frequently with the walls of the tyre, resulting in an increase in pressure.
(c) Fig. 3.2 shows a metal nut on the bicycle which is difficult to unscrew. (Sub-topic – P1.5.2)
Fig. 3.3 shows two spanners A and B.
Explain why it is easier to use spanner B to unscrew the nut rather than spanner A.
▶️Answer/Explanation
Spanner B is longer than spanner A. The turning effect (moment) of a force is calculated as Moment = Force × Distance from the pivot. Since spanner B has a longer handle, it provides a greater distance from the pivot, allowing a smaller force to produce the same turning effect, making it easier to unscrew the nut.
(d) The cyclist uses a plane mirror placed on his bicycle to see behind him.
State two characteristics of an image seen in a plane mirror. (Sub-topic – P3.2.1)
▶️Answer/Explanation
Two characteristics of an image seen in a plane mirror are:
- The image is upright.
- The image is laterally inverted (left and right are reversed).
Question 4
(a) Below list shows some information about feeding relationships in a national park. (Sub-topic – B18.2)
- Lions are the top predator. Lions eat jackals.
- Goats eat grass.
- Goats are eaten by jackals.
(i) Use the information to construct a food chain containing all the organisms.
▶️Answer/Explanation
Answer: grass → goat → jackal → lion
Explanation: The food chain starts with the producer (grass), which is eaten by the primary consumer (goat). The goat is then eaten by the secondary consumer (jackal), and finally, the jackal is eaten by the top predator (lion).
(ii) Use the information to identify the:
- producer
- secondary consumer
▶️Answer/Explanation
Answer:
Producer: grass
Secondary consumer: jackal
Explanation: The producer is the organism that produces its own food through photosynthesis, which is grass in this case. The secondary consumer is the organism that eats the primary consumer (goat), which is the jackal
(b) State the principal source of energy for all food chains. (Sub-topic – B18.1)
▶️Answer/Explanation
Answer: The Sun
Explanation: The Sun is the primary source of energy for all food chains. Producers (plants) convert solar energy into chemical energy through photosynthesis, which is then passed through the food chain.
(c) Table 4.1 shows the number and types of teeth for goats and humans. (Sub-topic – B7.1)
| Type of teeth | Number in goats | Number in humans |
|---|---|---|
| incisors | 8 | 8 |
| canines | 0 | 4 |
| premolars | 12 | 8 |
| molars | 12 | 12 |
(i) Goats have a greater total number of premolar and molar teeth than humans. Describe two other differences between the types and number of teeth in goats and humans.
▶️Answer/Explanation
Answer:
1. Goats have no canine teeth, while humans have 4 canine teeth.
2. Goats have more premolar teeth (12) compared to humans (8).
Explanation: Goats are herbivores and do not need canine teeth for tearing meat, which is why they have none. Humans, being omnivores, have canine teeth for tearing food. Additionally, goats have more premolar teeth to help them grind plant material.
(ii) Goats are herbivores. Humans are able to gain their energy by eating both animals and plants. Suggest reasons why goats have a greater total number of premolar and molar teeth than humans.
▶️Answer/Explanation
Answer:
Goats need more premolar and molar teeth to grind and break down tough plant material, which is their primary food source. Humans, being omnivores, have a more varied diet that includes both plant and animal matter, so they do not require as many grinding teeth.
Explanation: Herbivores like goats rely on plant material, which is tough and fibrous, requiring more grinding teeth (premolars and molars) to break it down effectively. Humans, with a more varied diet, have fewer grinding teeth because their diet includes softer foods like meat and cooked vegetables.
(iii) Circle the top two layers in a human tooth.
- cement
- dentine
- enamel
- gum
- pulp
- nerve
▶️Answer/Explanation
Answer: enamel and dentine
Explanation: The top two layers of a human tooth are the enamel, which is the hard outer layer, and the dentine, which lies beneath the enamel and is less hard but still protective.
Question 5
(a) Table 5.1 shows information about four metallic elements.
| Metal | Reaction of metal with water |
|---|---|
| Copper | Does not react with water |
| Iron | Reacts very slowly with water |
| Lithium | Reacts rapidly with water |
| Sodium | Reacts very rapidly with water |
(i) State the names of the two metals in Table 5.1 that are transition elements. (Sub-topic – C9.1)
▶️Answer/Explanation
Copper and iron
(ii) Suggest the name of the gas produced when an alkali metal reacts with water. (Sub-topic – C9.1)
▶️Answer/Explanation
Hydrogen
(iii) Place the four metals in order of reactivity from the most reactive to the least reactive. (Sub-topic – C9.4)
▶️Answer/Explanation
Sodium, lithium, iron, copper
(b) Copper is extracted by heating copper oxide with carbon.
The word equation for the reaction is shown.
copper oxide + carbon → copper + carbon dioxide
(i) Balance the symbol equation for this reaction. (Sub-topic – C3.1)
▶️Answer/Explanation
2CuO + C → 2Cu + CO2
(ii) Identify which substance is reduced during this reaction. Explain your answer. (Sub-topic – C6.3)
▶️Answer/Explanation
Copper oxide is reduced because it loses oxygen.
(c) During the extraction of copper, carbon dioxide is released into the air.
Carbon dioxide is found in small quantities in clean air.
(i) State the names of the two gases which are found in large quantities in clean air. (Sub-topic – C10.2)
▶️Answer/Explanation
Oxygen and nitrogen
(ii) Carbon dioxide is a greenhouse gas. State the name of one other greenhouse gas. (Sub-topic – C10.2)
▶️Answer/Explanation
Methane
(iii) Carbon dioxide is released into the air during the combustion of fossil fuels. State the names of two fossil fuels. (Sub-topic – C11.3)
▶️Answer/Explanation
Coal and petroleum
Question 6 (Topic – P4.3.2)
(a) A car has two identical headlamps. The lamps are connected in parallel across a 12V battery. A single switch is used to turn on both lamps.
(i) Draw a circuit diagram for this circuit using standard electrical symbols.
▶️Answer/Explanation
The circuit diagram should show:
- A 12V battery as the power source.
- Two lamps connected in parallel.
- A single switch controlling both lamps.
(ii) The resistance of each lamp is 3.0Ω. Calculate the current in each lamp when lit.
▶️Answer/Explanation
Using Ohm’s Law, \( V = IR \), the current \( I \) in each lamp is: \[ I = \frac{V}{R} = \frac{12V}{3.0\Omega} = 4A \] So, the current in each lamp is 4A.
(iii) State one reason why the lamps are connected in parallel and not in series.
▶️Answer/Explanation
The lamps are connected in parallel so that if one lamp fails, the other will still light up. In a series connection, if one lamp fails, the circuit is broken, and both lamps will turn off.
(b) A lamp consists of a glass bulb, which contains a thin metal filament attached to a metal base. The glass bulb is filled with nitrogen gas. When electricity passes through the lamp, the filament is at a very high temperature.
Fig 6.1 shows a lamp
Thermal energy is transferred from the hot filament through the nitrogen gas and through the glass bulb.
(i) State the method by which thermal energy is transferred by the nitrogen gas to the glass bulb.
▶️Answer/Explanation
The thermal energy is transferred by convection. The heated nitrogen gas rises and transfers heat to the glass bulb.
(ii) State the method by which thermal energy is transferred through the glass bulb.
▶️Answer/Explanation
The thermal energy is transferred through the glass bulb by conduction. Heat is conducted through the glass material.
(c) On a journey, a car becomes electrostatically charged. Describe what happens to cause the car to become charged.
▶️Answer/Explanation
The car becomes electrostatically charged due to friction between the car’s surface and the air or road. This friction causes electrons to be transferred, resulting in an imbalance of charges, making the car charged.
(d) Fig. 6.2 shows how damage to a steel door of the car has been repaired with a plastic filler. The filler has been painted over and cannot be seen.
Suggest how the owner of the car uses a magnet to detect the repair to the bodywork.
▶️Answer/Explanation
The owner can use a magnet to detect the repair because the steel door is magnetic, while the plastic filler is not. If the magnet does not stick to a certain area, it indicates the presence of the non-magnetic plastic filler, revealing the repair.
Question 7
(a) Table 7.1 shows some of the functions of the main components of blood. (Sub-topic – B9.4)
Complete Table 7.1 with the name of the component of blood for each function.
| Name of Component | Function of Component |
|---|---|
| blood clotting | |
| oxygen transport | |
| phagocytosis and antibody production | |
| used for transport of hormones |
▶️Answer/Explanation
1. Platelets
2. Red blood cells
3. White blood cells
4. Plasma
(b) Some of the substances transported by the blood need to be excreted. (Sub-topic – B1.1)
The boxes contain the beginnings and the endings of some sentences. Join one sentence beginning to one sentence ending to define the term excretion.
▶️Answer/Explanation
Excretion is the removal from organisms of toxic materials and substances in excess of requirements.
(c) Excretion, respiration and nutrition are three characteristics of living organisms. (Sub-topic – B1.1)
Name two other characteristics of living organisms.
▶️Answer/Explanation
1. Movement
2. Growth
Question 8 (Sub-topic – C2.5)
(a) Fig. 8.1 shows three molecules A, B and C.
State the formula of the substance that reacts with molecule C to make molecule A.
▶️Answer/Explanation
Answer: H2O
Explanation: Molecule C is CH4 (methane), and molecule A is CO2 (carbon dioxide). The reaction between methane and water (H2O) in the presence of oxygen produces carbon dioxide and water. Therefore, the substance that reacts with molecule C to make molecule A is H2O.
(b) Molecule B, CH4, is methane which is a compound. Methane contains the elements carbon and hydrogen.
Use this information to explain the difference between an element and a compound.
▶️Answer/Explanation
Answer: An element contains only one type of atom, while a compound contains two or more elements chemically combined.
Explanation: An element, such as carbon (C) or hydrogen (H), consists of only one type of atom. A compound, like methane (CH4), is made up of two or more different elements (carbon and hydrogen) that are chemically bonded together.
(c) State the two products made when methane undergoes complete combustion in oxygen.
▶️Answer/Explanation
Answer: Carbon dioxide (CO2) and water (H2O).
Explanation: When methane (CH4) undergoes complete combustion in the presence of oxygen (O2), it produces carbon dioxide (CO2) and water (H2O) as the products. The balanced chemical equation for this reaction is: CH4 + 2O2 → CO2 + 2H2O.
(d) The combustion of methane is an exothermic reaction.
State what is meant by exothermic.
▶️Answer/Explanation
Answer: An exothermic reaction releases thermal energy to the surroundings.
Explanation: In an exothermic reaction, energy is released in the form of heat to the surroundings. This results in an increase in the temperature of the surroundings. The combustion of methane is an example of an exothermic reaction because it releases heat energy.
(e) An atom of carbon has a nucleon number (mass number) of 12 and a proton number (atomic number) of 6.
An atom of hydrogen has a nucleon number (mass number) of 1 and a proton number (atomic number) of 1.
(i) State the number of electrons in an atom of carbon and in an atom of hydrogen.
▶️Answer/Explanation
Answer: Carbon: 6 electrons, Hydrogen: 1 electron.
Explanation: In a neutral atom, the number of electrons is equal to the number of protons. Carbon has 6 protons, so it has 6 electrons. Hydrogen has 1 proton, so it has 1 electron.
(ii) State the number of neutrons in this atom of hydrogen.
▶️Answer/Explanation
Answer: 0 neutrons.
Explanation: The number of neutrons in an atom is calculated by subtracting the proton number from the nucleon number. For hydrogen, the nucleon number is 1, and the proton number is 1, so the number of neutrons is 1 – 1 = 0.
(f) Complete the dot-and-cross diagram in Fig. 8.2 to show the bonding in a methane, CH4, molecule.
▶️Answer/Explanation
Answer: The dot-and-cross diagram should show one carbon atom sharing one pair of electrons with each of the four hydrogen atoms.
Explanation: In methane (CH4), the carbon atom forms four covalent bonds with four hydrogen atoms. Each bond is represented by a shared pair of electrons, with one electron from carbon and one from hydrogen. The dot-and-cross diagram should illustrate this sharing of electrons.
Question 9
(a) A school orchestra is practising.
Table 9.1 shows the highest and lowest sound frequencies of some of the musical instruments in the orchestra. (Sub-topic – P3.1)
| Instrument | Highest Frequency (Hz) | Lowest Frequency (Hz) |
|---|---|---|
| Flute | 2600 | 260 |
| Guitar | 1200 | 70 |
| Piano | 4200 | 30 |
| Violin | 3500 | 200 |
(i) State what is meant by the frequency of a wave.
▶️Answer/Explanation
The frequency of a wave is the number of waves produced per second or the number of waves passing a fixed point per second.
(ii) State which instrument in Table 9.1 produces the sound with the lowest pitch.
▶️Answer/Explanation
The piano produces the sound with the lowest pitch because it has the lowest frequency (30 Hz).
(iii) State which instrument in Table 9.1 produces sound with the widest range of frequencies.
▶️Answer/Explanation
The piano produces sound with the widest range of frequencies, from 30 Hz to 4200 Hz.
(iv) State the normal audible frequency range for a healthy human ear.
▶️Answer/Explanation
The normal audible frequency range for a healthy human ear is from 20 Hz to 20,000 Hz.
(b) A flute is made from a nickel alloy. The volume of the alloy used to make the flute is 90 cm3. The mass of the flute is 801 g. (Sub-topic – P1.4)
(i) Calculate the density of the alloy. State the unit of your answer.
▶️Answer/Explanation
Density = Mass / Volume = 801 g / 90 cm3 = 8.90 g/cm3.
(ii) Calculate the weight of the flute. The gravitational field strength \( g \) is 10 N/kg.
▶️Answer/Explanation
Weight = Mass × Gravitational field strength = 0.801 kg × 10 N/kg = 8.01 N.
Question 10 (Sub Topic – B15.3)
(a) Plants use different tissues to transport substances around the plant. Circle two parts of a plant that are adapted for transport from below list.
- capillaries
- chloroplasts
- fatty tissue
- guard cells
- phloem
- vena cava
- xylem
▶️Answer/Explanation
phloem and xylem
(b) Fig. 10.1 is a diagram of a plant cell.
(i) Name the cell shown in Fig. 10.1 and state its function.
▶️Answer/Explanation
name: root hair cell
function: absorption of water and mineral ions
(ii) Identify the parts labelled X and Y in Fig. 10.1.
▶️Answer/Explanation
X: cell wall
Y: nucleus
(c) A scientist investigates the conditions needed for the germination of seeds.
She sets up four experiments A–D with different conditions.
Table 10.1 shows the conditions for each experiment. Place a tick (✓) in Table 10.1 to identify the experiment where the seeds will germinate.
| experiment | temperature/°C | moisture | oxygen | do seeds germinate? (✓) |
|---|---|---|---|---|
| A | –20 | damp | present | |
| B | –20 | dry | absent | |
| C | 20 | damp | present | |
| D | 20 | dry | absent |
▶️Answer/Explanation
Experiment C will have a tick (✓) as it has the correct conditions for germination: suitable temperature (20°C), moisture (damp), and oxygen (present).
(d) Germination is an enzyme-controlled reaction. The investigation is repeated with boiled seeds. Describe the effect of boiling on the germination of seeds. Give one reason for your answer.
▶️Answer/Explanation
Effect: Boiling will prevent the seeds from germinating.
Reason: Boiling denatures the enzymes, which are essential for the metabolic processes required for germination.
Question 11
(a) Fig. 11.1 shows iron rusting. (Sub-topic – C9.5)
(i) Iron rusts when two other substances are present. State the names of these two substances.
▶️Answer/Explanation
Answer: Oxygen and water.
Explanation: Rusting of iron is a chemical reaction that occurs when iron is exposed to both oxygen and water. The reaction forms iron oxide, commonly known as rust.
(ii) Describe and explain one method used to prevent the rusting of iron.
▶️Answer/Explanation
Answer: Painting or coating the iron with a protective layer.
Explanation: Painting or coating the iron creates a barrier that prevents oxygen and water from coming into contact with the iron surface, thus preventing rusting. This method is commonly used in industries and for household items like gates and railings.
(b) Stainless steel is an alloy of iron. (Sub-topic – C9.3)
State one use for stainless steel.
▶️Answer/Explanation
Answer: Cutlery (knives, forks, spoons).
Explanation: Stainless steel is widely used in cutlery because it is resistant to rust and corrosion, making it durable and hygienic for food preparation and consumption.
(c) Solid iron melts at 1538 °C to become liquid (molten) iron. (Sub-topic – C1.1)
Describe one difference in the properties of a solid compared to a liquid.
▶️Answer/Explanation
Answer: A solid has a fixed shape, while a liquid takes the shape of its container.
Explanation: In a solid, the particles are tightly packed and have a fixed arrangement, giving the solid a definite shape. In a liquid, the particles are less tightly packed and can move around, allowing the liquid to flow and take the shape of its container.
(d) Melting is one of the processes involved when a substance changes state. (Sub-topic – C1.1)
Fig. 11.2 shows other processes involved when substances change state.
Identify processes A, B, and C.
▶️Answer/Explanation
Answer:
- A: Boiling
- B: Condensing
- C: Freezing
Explanation:
- Boiling (A): The process by which a liquid turns into a gas at its boiling point.
- Condensing (B): The process by which a gas turns into a liquid.
- Freezing (C): The process by which a liquid turns into a solid at its freezing point.
Question 12
(a) Describe how to show that a radioactive isotope is releasing γ-rays but not α-particles or β-particles. (Sub-topic – P5.2.2)
▶️Answer/Explanation
To show that a radioactive isotope is releasing γ-rays but not α-particles or β-particles, you can use a detector that is sensitive to γ-rays, such as a Geiger-Müller tube or a scintillation counter. Place the radioactive source near the detector and observe the readings. Since γ-rays are highly penetrating, they will be detected even if the source is shielded by materials like lead or thick concrete, which would block α and β particles. If the detector still registers radiation through such shielding, it indicates the presence of γ-rays. Additionally, α and β particles can be blocked by thin materials like paper or aluminum, so if the radiation is not blocked by these materials, it further confirms the presence of γ-rays.
(b) In a nuclear reactor, the fission of uranium-235 takes place.
(i) Describe what happens to the nucleus of a uranium-235 atom during nuclear fission. (Sub-topic – P5.2.3)
▶️Answer/Explanation
During nuclear fission, the nucleus of a uranium-235 atom absorbs a neutron, becoming unstable and splitting into two smaller nuclei (fission fragments), along with the release of additional neutrons and a large amount of energy in the form of kinetic energy and γ-rays.
(ii) The half-life of uranium-235 is 704 million years. A sample of uranium-235 has a mass of 0.1 g. Calculate how many grams of uranium-235 will remain in the sample after 704 million years.
(Sub-topic – P5.2.4)
▶️Answer/Explanation
After one half-life (704 million years), half of the original sample will have decayed. Therefore, the remaining mass of uranium-235 will be: \[ \text{Remaining mass} = \frac{0.1\, \text{g}}{2} = 0.05\, \text{g} \]
(iii) Uranium-235 and uranium-238 are two isotopes of uranium. Explain what is meant by isotope. (Sub-topic – P5.1)
▶️Answer/Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different mass numbers. For example, uranium-235 and uranium-238 both have 92 protons, but uranium-235 has 143 neutrons, while uranium-238 has 146 neutrons.
(c) A nuclear power station generates electricity. One use of electricity is to power an electric motor. In a d.c. electric motor, a current-carrying coil in a magnetic field experiences a turning effect. State two factors that can be changed to increase the turning effect in a d.c. motor. (Sub-topic – P4.5.5)
▶️Answer/Explanation
Two factors that can be changed to increase the turning effect in a d.c. motor are:
- Increase the current: A higher current in the coil will increase the magnetic force acting on the coil, resulting in a greater turning effect.
- Increase the strength of the magnetic field: A stronger magnetic field will also increase the force on the coil, leading to a greater turning effect.