Question 1
Sub-topic Code: B13.1 Coordination and response
(a) Fig. 1.1 shows three different types of neurones.
(i) Identify which drawing in Fig. 1.1, A, B or C, represents the motor neurone.
(ii) Describe how nerve impulses are passed along neurones.
(iii) Motor neurones are part of a reflex arc. Name the two other neurones found in a reflex arc.
(iv) Circle two words that can be used to describe a reflex action.
automatic conscious rapid slow stimulus voluntary
(b) Two students investigate reaction time. The students press a button as quickly as possible after the button lights up.
Table 1.1 shows the results.
(i) Calculate the average reaction time for student B. Give your value to two significant figures.
(ii) This reaction is a voluntary reaction. This is similar to a reflex arc but involves the brain. In this reaction, suggest the name of the:
effector ……
coordinator. ……
▶️Answer/Explanation
(a) (i) B
The motor neurone is responsible for carrying signals from the central nervous system to the muscles or glands. In Fig. 1.1, neurone B is identified as the motor neurone because it has a long axon that connects to the effector (muscle or gland).
(ii) Nerve impulses are passed along neurones as electrical signals.
Nerve impulses are transmitted along neurones as electrical signals. These signals are generated by the movement of ions across the neurone’s membrane, creating an action potential that travels along the axon
(iii) Sensory neurone and relay neurone.
In a reflex arc, the sensory neurone detects the stimulus and sends the signal to the relay neurone in the spinal cord. The relay neurone then passes the signal to the motor neurone, which triggers the response in the effector (muscle or gland).
(iv) automatic and rapid.
A reflex action is automatic (it happens without conscious thought) and rapid (it occurs quickly to protect the body from harm).
(b) (i) 0.15 s
To calculate the average reaction time for student B, add the reaction times for all five tests and divide by 5:
Average = (0.15 + 0.15 + 0.16 + 0.16 + 0.15) / 5 = 0.154 s ≈ 0.15 s (to two significant figures).
(ii) effector: muscles (in hand/finger); coordinator: brain/CNS.
In a voluntary reaction, the effector is the muscle that carries out the action (e.g., the muscles in the hand or finger that press the button). The coordinator is the brain or central nervous system (CNS), which processes the information and sends the signal to the effector.
Question 2
Sub-topic Code: C2.2 (Atomic structure and the Periodic Table)
(a) Table 2.1 shows a list of six elements.
| Name of Element |
|---|
| Copper |
| Helium |
| Magnesium |
| Nitrogen |
| Oxygen |
| Sodium |
(i) State the names of two metallic elements from Table 2.1.
(ii) State the name of an element from Table 2.1 which is 78% of clean air.
(iii) State the name of a noble gas from Table 2.1.
(iv) State the name of a transition element from Table 2.1.
▶️Answer/Explanation
(i) Copper and Magnesium (or Sodium) are metallic elements.
Metallic elements are those that have properties typical of metals, such as being good conductors of electricity and heat, malleability, and ductility. From the table, Copper (Cu), Magnesium (Mg), and Sodium (Na) are all metallic elements. Therefore, any two of these can be chosen as the answer.
(ii) Nitrogen is 78% of clean air.
Clean air is composed of approximately 78% nitrogen (N2), 21% oxygen (O2), and 1% other gases. Therefore, nitrogen is the element that makes up 78% of clean air.
(iii) Helium is a noble gas.
Noble gases are a group of chemical elements with very low reactivity. Helium (He) is one of the noble gases, and it is listed in Table 2.1.
(iv) Copper is a transition element.
Transition elements are found in the d-block of the periodic table and are characterized by their ability to form various oxidation states. Copper (Cu) is a transition element, as it is located in the d-block of the periodic table.
(b) Excess magnesium powder reacts with dilute hydrochloric acid. During this reaction, a gas and an aqueous solution of a salt are made.
(i) State the chemical formula of the gas made.
(ii) State the name of the salt made.
(iii) Some solid magnesium remains unreacted. State the method used to remove the unreacted solid magnesium from the reaction mixture.
(iv) The rate of reaction is decreased by decreasing the concentration of the hydrochloric acid.
State two other ways of decreasing the rate of this reaction.
▶️Answer/Explanation
2(b)(i) H2;
2(b)(ii) magnesium chloride;
2(b)(iii) filtration;
2(b)(iv) decrease surface area / increase particle size of magnesium;
decrease temperature (of acid);
(c) Table 2.2 shows the composition of an alloy of magnesium.
(i) State what is meant by the term alloy.
(ii) Calculate the mass of magnesium in 2000 kg of this alloy.
▶️Answer/Explanation
2(c)(i) mixture of metals / mixture of a metal and another element; 1
2(c)(ii) 1840 (kg) ;
Question 3
Subtopic Code: P3.1 General properties of waves
(a) X-rays and γ-radiation are used in hospitals.
(i) State one use of X-rays in a hospital.
▶️Answer/Explanation
X-rays are commonly used in hospitals to diagnose fractures and other bone-related issues. They provide images of the internal structure of the body, particularly bones, which helps doctors identify breaks or abnormalities.
(ii) Write X-rays in the correct place in the incomplete electromagnetic spectrum shown in Fig. 3.1.
▶️Answer/Explanation
The electromagnetic spectrum is arranged in order of increasing frequency: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and γ-radiation. X-rays have a higher frequency than visible light but lower than γ-radiation.
(iii) X-rays and γ-radiation are forms of ionising radiation. State one harmful effect of ionising radiation on humans.
▶️Answer/Explanation
Ionising radiation, such as X-rays and γ-radiation, has enough energy to remove tightly bound electrons from atoms, creating ions. This can damage DNA, leading to mutations or cancer over time.
(b) (i) Fig. 3.2 represents a sound wave.
Draw one line from each wave property to its description.
▶️Answer/Explanation
Amplitude refers to the height of the wave from its midpoint to its peak. Frequency is the number of wave cycles that pass a point per second. Wavelength is the distance between two consecutive peaks or troughs of a wave.
(ii) State the approximate range of audible frequencies for a healthy human ear.
▶️Answer/Explanation
Humans can generally hear sounds within the frequency range of 20 Hz to 20,000 Hz. Sounds below 20 Hz are called infrasound, and sounds above 20,000 Hz are called ultrasound.
(iii) A student determines the speed of sound in air. State the two measurements that she makes. Describe how she uses these measurements to calculate the speed of sound.
▶️Answer/Explanation
To determine the speed of sound, the student measures the distance between the sound source and the receiver and the time it takes for the sound to travel that distance. Using the formula speed = distance / time, she can calculate the speed of sound in air.
Question 4
Sub-topic: B5.1 Enzymes
(a) Different digestive enzymes work best at different pH values. The best pH for enzyme activity is called its optimum pH.
Fig. 4.1 shows the optimum pH of five different digestive enzymes.
Use Fig. 4.1 to complete these sentences:
The enzyme with the lowest optimum pH is enzyme …….
The two enzymes with the same optimum pH are enzymes …… and …….
The enzyme that works best in neutral conditions is enzyme …….
▶️Answer/Explanation
The enzyme with the lowest optimum pH is enzyme B.
The two enzymes with the same optimum pH are enzymes A and C.
The enzyme that works best in neutral conditions is enzyme E.
(b) Name one factor, other than pH, that affects enzyme activity.
▶️Answer/Explanation
Temperature.
(c) Complete this definition of an enzyme.
Enzymes are proteins that function as …… catalysts.
▶️Answer/Explanation
Biological.
(d) Carbohydrate, protein and fat are made from chemical elements. Place ticks (✓) in the boxes in Table 4.1 to show all the correct elements each substance is made from.
| Substance | Carbon | Hydrogen | Oxygen | Nitrogen |
|---|---|---|---|---|
| Carbohydrate | ||||
| Protein | ||||
| Fat |
▶️Answer/Explanation
Table 4.1:
| Substance | Carbon | Hydrogen | Oxygen | Nitrogen |
|---|---|---|---|---|
| Carbohydrate | ✓ | ✓ | ✓ | |
| Protein | ✓ | ✓ | ✓ | ✓ |
| Fat | ✓ | ✓ | ✓ |
(e)(i) Starch is a carbohydrate. State the name of the smaller molecules that starch is made from.
▶️Answer/Explanation
Glucose.
(ii) Circle the name of one other carbohydrate.
amino acid fatty acid glycogen oil
▶️Answer/Explanation
Glycogen.
Question 5
Sub-topic: C9.4 Reactivity series
(a) A student adds calcium and copper to separate test-tubes of cold water. Describe the reaction, if any, for each metal.
▶️Answer/Explanation
Calcium: Gas evolved / metal dissolves / white insoluble solid forms.
Copper: No change.
(b) The student reacts copper carbonate with dilute sulfuric acid. Copper(II) sulfate, carbon dioxide and water are made.
(i) Complete the word equation for this reaction.
▶️Answer/Explanation
Copper carbonate + sulfuric acid → copper sulfate + carbon dioxide + water.
(ii) Carbon dioxide gas is a greenhouse gas. State the name of one other greenhouse gas.
▶️Answer/Explanation
Methane.
(iii) The formula of copper(II) sulfate is CuSO4. State the number of different elements and the total number of atoms shown in this formula.
▶️Answer/Explanation
Number of elements: 3 (Copper, Sulfur, Oxygen).
Number of atoms: 6 (1 Cu, 1 S, 4 O).
(c) Copper oxide, CuO, is reduced to copper, Cu, by heating with carbon. The equation for the reaction is shown.
2CuO + C → 2Cu + CO2
(i) Explain how the equation shows that copper oxide, CuO, is reduced.
▶️Answer/Explanation
Copper oxide loses oxygen, which is the definition of reduction.
(ii) The reaction between copper oxide and carbon is exothermic. State what is meant by exothermic.
▶️Answer/Explanation
Exothermic reactions release energy to the surroundings, usually in the form of heat.
(iii) Name a metal, other than copper, that can be extracted from its ore by heating with carbon.
▶️Answer/Explanation
Iron.
Question 6
Sub-topic: P1.5.1 Effects of forces
(a) A farmer uses solar panels to generate the electricity needed for his farm.
Suggest why the farmer should have an alternative method of generating electricity rather than relying on just solar energy.
▶️Answer/Explanation
Solar panels only generate electricity during daylight hours and are dependent on weather conditions. Therefore, the farmer should have an alternative method to ensure a continuous supply of electricity, especially during the night or on cloudy days.
(b) Fig. 6.1 shows the farmer driving his tractor. Four forces, A, B, C, and D, are acting on the tractor.
The tractor is moving at a constant speed. The weight of the tractor is 40,000 N.
(i) State which force, A, B, C, or D, is the weight of the tractor.
▶️Answer/Explanation
Force C is the weight of the tractor.
(ii) Calculate the mass of the tractor. The gravitational field strength, g, is 10 N/kg.
▶️Answer/Explanation
Using the formula \( W = mg \), where \( W \) is the weight and \( g \) is the gravitational field strength:
\( m = \frac{W}{g} = \frac{40,000}{10} = 4,000 \, \text{kg} \).
(iii) Force B is 2,000 N. State the value of force D. Explain your answer.
▶️Answer/Explanation
Force D is 2,000 N. Since the tractor is moving at a constant speed, the forces acting on it are balanced. Therefore, the force opposing the motion (force D) must be equal to the driving force (force B).
(c) The tractor uses diesel fuel. State the form of energy stored in the diesel fuel.
▶️Answer/Explanation
The form of energy stored in diesel fuel is chemical (potential) energy.
(d) The farmer drives his tractor across a field. Fig. 6.2 shows the speed-time graph for the tractor.
(i) State the maximum speed of the tractor.
▶️Answer/Explanation
The maximum speed of the tractor is 2.0 m/s.
(ii) On Fig. 6.2, mark with an X a time when the tractor is moving with changing speed.
▶️Answer/Explanation
An X should be marked at any time between 0 and 5 seconds or between 15 and 20 seconds, as these are the periods when the speed is changing.
(iii) Calculate the distance travelled by the tractor between time = 15 s and time = 20 s.
▶️Answer/Explanation
The distance travelled can be calculated by finding the area under the speed-time graph between 15 s and 20 s. The shape is a triangle with a base of 5 s and a height of 2 m/s:
\( \text{Distance} = \frac{1}{2} \times \text{base} \times \text{height} = \frac{1}{2} \times 5 \times 2 = 5 \, \text{m} \).
Question 7
Sub-topic: B11.1 Gas exchange in humans
(a) Fig. 7.1 is a diagram of the gas exchange system in humans.
(i) Draw a label line and the name to identify a rib on Fig. 7.1.
(ii) Draw a label line and the name to identify the diaphragm on Fig. 7.1.
(b) Describe how inspired air is different from expired air.
(c) Name one of the main blood vessels that connects the lungs with the heart.
(d) Blood transports substances around the body.
(i) State the name of the part of the blood that transports oxygen.
(ii) State the name of the part of the blood that transports hormones.
(e) State the name of the hormone secreted in a ‘fight or flight’ situation.
▶️Answer/Explanation
(a) (i) and (ii): Rib and diaphragm should be correctly labelled on the diagram.
Detailed Solution: The rib and diaphragm are key structures in the gas exchange system. The rib is part of the ribcage that protects the lungs, while the diaphragm is a muscle that helps in breathing by contracting and relaxing to change the volume of the thoracic cavity.
(b) Inspired air contains more oxygen and less carbon dioxide compared to expired air. Expired air has more water vapor and carbon dioxide, and less oxygen.
Detailed Solution: Inspired air is the air we breathe in, which is rich in oxygen and has less carbon dioxide. Expired air is the air we breathe out, which has more carbon dioxide and water vapor due to the exchange of gases in the lungs.
(c) Pulmonary vein or pulmonary artery.
Detailed Solution: The pulmonary vein carries oxygenated blood from the lungs to the heart, while the pulmonary artery carries deoxygenated blood from the heart to the lungs.
(d) (i) Red blood cells.
Red blood cells contain hemoglobin, which binds to oxygen and transports it throughout the body.
(d) (ii) Plasma.
Plasma is the liquid component of blood that carries hormones, nutrients, and waste products.
(e) Adrenaline.
Adrenaline is a hormone secreted by the adrenal glands during stressful situations, preparing the body for a ‘fight or flight’ response by increasing heart rate, dilating airways, and redirecting blood flow to muscles.
Question 8
Sub-topic Code: B13.1 Coordination and response
(a) Table 8.1 shows information about some of the halogens in the Periodic Table.
(i) Complete Table 8.1.
(ii) Halogen molecules are diatomic. State the formula of a molecule of bromine.
(iii) State the group number of the halogens in the Periodic Table.
(iv) State the number of electrons in an iodine atom.
▶️Answer/Explanation
(a)(i) chlorine – gas;
iodine –solid ;
(a)(ii) Br2; 1
(a)(iii) seven / VII ; 1
(a)(iv) 53;
(b) State the type of bond made when chlorine reacts with hydrogen to make the gas hydrogen chloride, HCl.
Explain your answer.
▶️Answer/Explanation
(b) covalent ;
between two non metals/electrons are shared;
(c) Fig. 8.1 shows the apparatus used in the electrolysis of molten lead(II) bromide.
(i) State which letter, A–F, in Fig. 8.1 identifies the:
- anode
- cathode
- electrolyte.
(ii) State the two products of this electrolysis.
▶️Answer/Explanation
(i)
- Anode: C
- Cathode: E
- Electrolyte: D
Detailed Solution:
(i) In the electrolysis of molten lead(II) bromide, the anode is the positive electrode where bromide ions (Br⁻) are oxidized to form bromine gas (Br₂). The cathode is the negative electrode where lead ions (Pb²⁺) are reduced to form lead metal (Pb). The electrolyte is the molten lead(II) bromide (PbBr₂) that conducts electricity by the movement of ions.
(ii)
- Bromine
- Lead
Detailed Solution:
(ii) During the electrolysis of molten lead(II) bromide, the products formed are:
- At the anode: Bromine gas (Br₂) is produced due to the oxidation of bromide ions (Br⁻).
- At the cathode: Lead metal (Pb) is produced due to the reduction of lead ions (Pb²⁺).
This process demonstrates the decomposition of lead(II) bromide into its constituent elements through the application of an electric current.
Question 9
(a) Table 9.1 contains descriptions of a solid, a liquid, and a gas. Complete Table 9.1 using the words in the list. (Sub-topic: C1.1)
solid liquid gas
Use each word once only.
| Description | Solid, Liquid, or Gas |
|---|---|
| The particles have a random arrangement and are close together | …… |
| The particles have a regular arrangement and are close together | …… |
| The particles have a random arrangement and are widely separated from each other | …… |
▶️Answer/Explanation
Answer:
The particles have a random arrangement and are close together = liquid
The particles have a regular arrangement and are close together = solid
The particles have a random arrangement and are widely separated from each other = gas
(b) Some water is heated in a copper saucepan on the hot-plate of an electric cooker. This is shown in Fig. 9.1. (Sub-topic: P2.3)
(i) State the main method of thermal energy transfer through:
the copper saucepan
the water.
▶️Answer/Explanation
Answer:
The main method of thermal energy transfer through:
the copper saucepan = conduction
the water = convection
(ii) Suggest why the handle of the saucepan is made from plastic and not copper.
▶️Answer/Explanation
Answer:
The handle of the saucepan is made from plastic because plastic is an insulator, which means it does not conduct heat well. This prevents the handle from becoming too hot to touch when the saucepan is heated.
(c) An electric circuit contains a copper wire. The current in the copper wire is 0.5 A. The potential difference (p.d.) across the copper wire is 4.0 V. (Sub-topic: P4.2.4)
Calculate the resistance of the wire. State the unit of your answer.
▶️Answer/Explanation
Answer:
Using Ohm’s Law: \( R = \frac{V}{I} \)
\( R = \frac{4.0}{0.5} = 8 \, \Omega \)
The resistance of the wire is 8 Ω.
(d) Fig. 9.2 shows a copper wire placed between the poles of a magnet. (Sub-topic: P4.5.4)
When the switch is closed, the wire moves upwards. State how this observation would change if the current is reversed.
▶️Answer/Explanation
Answer:
If the current is reversed, the direction of the force on the wire will also reverse. Therefore, the wire will move downwards instead of upwards.
Question 10
Sub-topic Code: B6.1 Photosynthesis
(a) Fig. 10.1 is a diagram of a cross-section through a leaf.
(i) Identify the letter in Fig. 10.1 that represents:
- where photosynthesis occurs
- the part which controls the cell’s activities
- where water vapour is lost from the leaf.
(ii) State the name of the part labelled E in Fig. 10.1.
(b) A student investigates which substances are needed for photosynthesis. The student removes different substances from the environment the plant is in. They then record if the plant photosynthesises. Table 10.1 shows a summary of their results.
(i) Use the information in Table 10.1 to identify which substance is not required for photosynthesis.
(ii) During the investigation, the student uses a lamp to provide a source of light. Predict the effect on photosynthesis if the investigation is repeated with no light. Give a reason for your answer.
(c) Mineral ions are also required for plant health.
(i) State the main mineral ion required for making chlorophyll.
(ii) State the name of the cell where mineral ions enter a plant.
(d) Describe the function of phloem in a plant.
▶️Answer/Explanation
(a) (i)
- Photosynthesis occurs in C (palisade mesophyll cells).
- The part which controls the cell’s activities is A (nucleus).
- Water vapour is lost from the leaf through F (stomata).
(a) (ii) The part labelled E is the lower epidermis.
(b) (i) The substance not required for photosynthesis is oxygen.
(b) (ii)
- Prediction: Photosynthesis will not occur.
- Reason: Light is required for the light-dependent reactions of photosynthesis, which produce ATP and NADPH needed for the Calvin cycle.
(c) (i) The main mineral ion required for making chlorophyll is magnesium.
(c) (ii) Mineral ions enter a plant through root hair cells.
(d) The function of phloem in a plant is to transport sucrose and amino acids from sources (e.g., leaves) to sinks (e.g., roots, fruits) for growth and storage.
Question 11
Sub-topic: C11.1
Fig. 11.1 shows the structures of four molecules, P, Q, R and S.
(a) (i) State which of the molecules P, Q, R or S is an alkene.
▶️Answer/Explanation
S
Detailed Solution: An alkene is a hydrocarbon with at least one carbon-carbon double bond. In Fig. 11.1, molecule S has a double bond, making it an alkene.
(ii) State which of the molecules P, Q, R or S is ethanol.
▶️Answer/Explanation
Q
Detailed Solution: Ethanol is an alcohol with the formula C2H5OH. Molecule Q matches this structure.
(iii) State which of the molecules P, Q, R or S is the main constituent of natural gas.
▶️Answer/Explanation
R
Detailed Solution: The main constituent of natural gas is methane (CH4). Molecule R represents methane.
(iv) State which two of the molecules P, Q, R and S are saturated hydrocarbons.
▶️Answer/Explanation
P and R
Detailed Solution: Saturated hydrocarbons have only single bonds between carbon atoms. Molecules P and R are saturated hydrocarbons.
(b) Carbon dioxide is made during the complete combustion of substance R. State the name of the other product made in this reaction.
▶️Answer/Explanation
Water
Detailed Solution: The complete combustion of methane (R) produces carbon dioxide (CO2) and water (H2O).
(c) Molecule S is a compound made from the two elements carbon and hydrogen. State what is meant by a compound.
▶️Answer/Explanation
A compound contains two or more elements chemically combined.
Detailed Solution: A compound is a substance formed when two or more elements are chemically bonded together.
(d) Deduce the formula of molecule P.
▶️Answer/Explanation
C3H6
Detailed Solution: Molecule P is propene, which has the formula C3H6.
(e) Fig. 11.2 shows an incomplete dot-and-cross diagram for molecule R. Complete Fig. 11.2. Show the outer-shell electrons only.
▶️Answer/Explanation
One bonding pair and all else correct.
Detailed Solution: Molecule R is methane (CH4). The dot-and-cross diagram should show one bonding pair of electrons between each hydrogen atom and the carbon atom.
Question 12
Sub-topic: P1.5.2
(a) During a journey, a car becomes positively charged with static electricity. State the name of the charged particles that have been removed from the car.
(b) The car has two headlamps powered by the car battery. The lamps are connected in parallel. Complete the circuit diagram in Fig. 12.1 to show two lamps connected in parallel both controlled by one switch. The battery has been drawn for you.
(c) The driver of the car changes a wheel. Fig. 12.2 shows a wheel nut being loosened by a spanner.
The driver uses a force of 1200 N on the spanner. Calculate the moment of this force on the wheel nut in Nm.
(d) The car driver uses a mirror to see behind the car. Fig. 12.3 shows the driver looking into a plane mirror. He can see the reflection of a street lamp.
(i) State the name of the line labelled XY.
(ii) On Fig. 12.3, label the angle of incidence with the letter \(i\).
(iii) Circle two words or phrases that correctly describe the image of the street lamp seen in the mirror.
larger laterally inverted same size smaller upside down
▶️Answer/Explanation
(a) Answer: electrons
Explanation: When a car becomes positively charged, it means that electrons have been removed from it. Electrons are negatively charged particles, so their removal leaves the car with a net positive charge.
(b) Answer: The circuit diagram should show the two lamps connected in parallel with the battery and controlled by one switch. The switch should be placed in the main line before the lamps branch out.
Explanation: In a parallel circuit, each component is connected across the same voltage, and the current divides between the branches. The switch controls both lamps simultaneously.
(c) Answer: 660 Nm
Explanation: The moment of a force is calculated using the formula: \[ \text{Moment} = \text{Force} \times \text{Distance} \] Given that the force is 1200 N and the distance (length of the spanner) is 55 cm (0.55 m), the moment is: \[ \text{Moment} = 1200 \, \text{N} \times 0.55 \, \text{m} = 660 \, \text{Nm} \]
(d)(i) Answer: normal
Explanation: The line labelled XY is the normal, which is an imaginary line perpendicular to the surface of the mirror at the point where the light ray strikes it.
(d)(ii) Answer: The angle of incidence should be labelled with the letter \(i\) between the incident ray and the normal.
Explanation: The angle of incidence is the angle between the incident ray and the normal to the mirror’s surface.
(d)(iii) Answer: same size, laterally inverted
Explanation: The image formed by a plane mirror is always the same size as the object and is laterally inverted (left and right are swapped).