Question 1
where photosynthesis occurs ……………………………………………………………………………….
where the genetic material is found ……………………………………………………………………….
that controls what substances enter the cell ……………………………………………………………
The student measures the length of the potato before and after immersion.
Table 1.1 is a summary of the results.
The potato with the smallest change in length has been immersed in a sucrose solution with a concentration of ………………………………….. mol/dm\(^3\).
The potato immersed in \(0.8 \, \text{mol/dm}^3\) sucrose solution changed by ………………………………….. mm in length.
The potato immersed in \(0.2 \, \text{mol/dm}^3\) sucrose solution increases in length because water is absorbed by the potato cells by the process of ………………………………….. .
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B2.1 — Cell structure (Parts (a)(i), (a)(ii), (a)(iii))
• Topic B3.2 — Osmosis (Parts (b)(i), (b)(ii))
▶️ Answer/Explanation
(a)(i) A, E, D
Photosynthesis occurs in the chloroplast, labelled A.
The genetic material is found in the nucleus, labelled E.
The cell membrane, labelled D, controls what substances enter the cell.
(a)(ii) Cytoplasm
Part B in Fig. 1.1 is the jelly-like substance filling the cell, which is the cytoplasm.
It is the site of many chemical reactions in the cell.
(a)(iii) Chloroplast and vacuole (or cell wall)
Plant cells contain a chloroplast for photosynthesis, which animal cells lack.
Plant cells also have a permanent vacuole and a cellulose cell wall, structures not found in animal cells.
(b)(i) +1.1 mm
Change in length = length at the end − length at the start.
Change = \(46.7 – 45.6 = 1.1 \, \text{mm}\).
This is an increase, so the value is \(+1.1 \, \text{mm}\).
(b)(ii) 0.6 mol/dm³; −1.1 mm; osmosis
The smallest change in length (+0.6 mm) occurs at \(0.6 \, \text{mol/dm}^3\).
The potato in \(0.8 \, \text{mol/dm}^3\) solution changed by \(-1.1 \, \text{mm}\) (a decrease, as water left the cells).
Water moves into the potato cells from a dilute solution by osmosis, down the water potential gradient.
Question 2
Draw one straight line from each word to its correct description.
Fig. 2.1 shows the apparatus the student uses.
Calculate the rate at which carbon dioxide is made in \(\text{cm}^3/\text{s}\).
State the number of different elements present in calcium carbonate.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topics C2.1, C2.4, C12.3 — Elements/compounds/mixtures, Ions and ionic bonds, Chromatography (Part (a))
• Topic C12.1 — Experimental design (Part (b)(i))
• Topic C7.3 — Preparation of salts (Part (b)(ii))
• Topic C12.5 — Identification of ions and gases (Part (b)(iii))
• Topic C6.2 — Rate of reaction (Parts (b)(iv), (b)(v))
• Topic C2.1 — Elements, compounds and mixtures (Part (b)(vi))
▶️ Answer/Explanation
(a)
Ion is an atom that has gained or lost electrons.
Sodium is an element in Group I of the Periodic Table.
Solute is a substance that dissolves in a solvent.
Chromatography is a technique used to separate dyes.
Sulfur is used in the production of sulfuric acid.
(b)(i) Measuring cylinder
Apparatus A is used to collect and measure the volume of gas produced by downward displacement of water.
Its graduated scale allows the volume of carbon dioxide to be read directly.
(b)(ii) Calcium chloride
Calcium carbonate reacts with hydrochloric acid to form a calcium salt.
Since hydrochloric acid is used, the salt formed is calcium chloride.
(b)(iii) Bubble the gas through limewater; it turns milky/cloudy
Carbon dioxide is tested for by bubbling the gas through limewater.
A positive result is shown by the limewater turning milky or cloudy.
(b)(iv) 1.8 cm³/s
Rate = volume ÷ time.
Rate = \(\dfrac{90 \, \text{cm}^3}{50 \, \text{s}} = 1.8 \, \text{cm}^3/\text{s}\).
(b)(v) Lower temperature of acid; lower concentration of acid (or decrease surface area)
Reducing the temperature of the acid slows down particle collisions, reducing the rate.
Reducing the concentration of the acid also lowers the frequency of successful collisions.
Alternatively, decreasing the surface area of the calcium carbonate would reduce the rate.
(b)(vi) 3
The formula \(\text{CaCO}_3\) contains calcium (Ca), carbon (C), and oxygen (O).
This gives a total of 3 different elements.
Question 3
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.3 — Energy resources (Parts (a), (b))
• Topic P5.2.4 — Half-life (Part (c)(i))
• Topic P5.2.2 — The three types of nuclear emission (Parts (c)(ii), (c)(iii))
• Topic P5.2.5 — Applications and safety precautions (Part (c)(iv))
▶️ Answer/Explanation
(a) Thermal energy turns water to steam; steam drives a turbine; turbine drives a generator
The thermal energy released by combustion boils water to produce high-pressure steam.
This steam is used to spin a turbine.
The turbine is connected to a generator, which converts the kinetic energy into electrical energy.
(b) Advantage: not reliant on fossil fuels / no CO₂ produced. Disadvantage: risk of nuclear accidents / disposal of nuclear waste
Nuclear power stations do not burn fossil fuels, so they don’t release carbon dioxide during operation.
However, they carry the risk of nuclear accidents and produce radioactive waste that is difficult and costly to dispose of safely.
(c)(i) 0.125 g
Number of half-lives = \(21 \div 5.25 = 4\).
Mass remaining = \(2 \, \text{g} \times \left(\dfrac{1}{2}\right)^4 = 2 \times \dfrac{1}{16} = 0.125 \, \text{g}\).
(c)(ii) −1
A β-particle is a fast-moving electron emitted from the nucleus.
It carries a charge of \(-1\).
(c)(iii) Most penetrating: γ-rays; then β-particles; least penetrating: α-particles
γ-rays are electromagnetic radiation with no mass or charge, giving them the greatest penetrating power.
β-particles penetrate less than γ-rays but more than α-particles.
α-particles are large and heavily charged, so they are stopped easily and have the least penetrating power.
(c)(iv) Store in a lead-lined container
A lead-lined container absorbs the emitted radiation.
This prevents the radiation from escaping and harming people nearby.
Question 4
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B9.3 — Blood vessels (Parts (a)(i), (a)(ii), (b), (c))
• Topic B9.4 — Blood (Part (d))
▶️ Answer/Explanation
(a)(i) Thicker wall; narrower lumen
Arteries have a much thicker muscular and elastic wall than veins.
Arteries also have a narrower lumen (internal space) compared with the vein shown.
(a)(ii) Valves
Veins contain valves along their length to prevent the backflow of blood.
These valves are not visible in the simple cross-sectional photomicrograph shown.
(b) Pulmonary vein; vena cava
The pulmonary vein carries oxygenated blood from the lungs to the heart.
The vena cava carries deoxygenated blood from the body back to the heart.
(c) Capillaries transfer oxygen and nutrients to tissues/cells (or transfer carbon dioxide/waste away from tissues/cells)
Capillary walls are extremely thin, allowing efficient exchange of substances with surrounding tissues.
They deliver oxygen and nutrients to cells and remove carbon dioxide and other waste products.
(d) White blood cell — antibody production and phagocytosis; Platelets — blood clotting; Plasma — transport of blood cells and ions; Red blood cell — transport of oxygen
White blood cells produce antibodies and engulf pathogens by phagocytosis.
Platelets are cell fragments involved in blood clotting at wound sites.
Plasma is the liquid component that carries blood cells, ions, and dissolved substances around the body.
Red blood cells contain haemoglobin, which binds and transports oxygen.
Question 5
Use the reactivity series to predict the result when calcium reacts with cold water. Explain your answer.
State what is meant by the term exothermic.
State two properties of platinum that are not properties of magnesium.
Calculate the mass of magnesium in \(1.0 \, \text{kg}\) of the alloy.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic C2.2 — Atomic structure and the Periodic Table (Part (a))
• Topic C9.4 — Reactivity series (Part (b))
• Topic C6.1 — Physical and chemical changes (Part (c)(i))
• Topic C5.1 — Exothermic and endothermic reactions (Part (c)(ii))
• Topic C8.4 — Transition elements (Part (d))
• Topic C9.3 — Alloys and their properties (Part (e))
▶️ Answer/Explanation
(a)
Number of neutrons = nucleon number − proton number = \(26 – 12 = 14\).
Number of electrons equals the number of protons in a neutral atom, so it is 12.
(b) Calcium reacts more quickly than magnesium, because calcium is higher in the reactivity series
Calcium is positioned above magnesium in the reactivity series shown in Fig. 5.1.
A more reactive metal reacts faster with cold water, so calcium reacts more vigorously than magnesium.
(c)(i) Magnesium + carbon dioxide → magnesium oxide + carbon
Magnesium displaces carbon from carbon dioxide because magnesium is more reactive.
This forms magnesium oxide and releases solid carbon.
(c)(ii) Exothermic means the reaction releases (thermal) energy
In an exothermic reaction, energy is transferred from the chemicals to the surroundings.
This is usually seen as a rise in temperature.
(d) Forms coloured compounds; acts as a catalyst (or has variable valency)
Platinum, as a transition metal, can form coloured compounds, unlike magnesium.
Transition metals like platinum can also act as catalysts and show variable valency (ionic charge), properties magnesium does not have.
(e) 91.5%; 0.915 kg
Percentage of magnesium = \(100 – (6.0 + 2.0 + 0.4 + 0.1) = 91.5\%\).
Mass of magnesium in \(1.0 \, \text{kg}\) of alloy = \(\dfrac{91.5}{100} \times 1.0 = 0.915 \, \text{kg}\).
Question 6
The gravitational field strength, \(g\), is \(10 \, \text{N/kg}\).
Calculate the average density of the elephant.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.2 — Work (Part (a)(i))
• Topic P1.6.1 — Energy (Part (a)(ii))
• Topic P1.3 — Mass and weight (Part (b)(i))
• Topic P1.4 — Density (Part (b)(ii))
• Topic P1.1 — Physical quantities and measurement techniques (Part (c))
▶️ Answer/Explanation
(a)(i) Force; distance
Work done is calculated using \(W = F \times d\).
So the elephant’s applied force and the distance the log moves must both be measured.
(a)(ii) Gravitational potential energy
As the elephant moves up the hill, its height above the ground increases.
This increases its gravitational potential energy.
(b)(i) 36 800 N
Combined mass = \(3500 + 180 = 3680 \, \text{kg}\).
Weight = \(mg = 3680 \times 10 = 36{,}800 \, \text{N}\).
(b)(ii) 1029 kg/m³
Density = mass ÷ volume.
Density = \(\dfrac{3500}{3.4} \approx 1029 \, \text{kg/m}^3\).
(c) Area of one foot — m²; length of a tusk — m; body temperature — °C
Area is measured in square metres (m²), so the unit for area of one foot is m².
Length is measured in metres (m), so the tusk length uses m.
Temperature is measured in degrees Celsius (°C).
Question 7
The boxes on the right contain the different functions of the types of teeth.
Draw one line from each type of tooth to its correct function.
Two types of teeth have the same function.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B7.1 — Diet (Parts (a)(i), (a)(ii), (b), (c))
• Topic B7.3 — Digestion (Part (d))
▶️ Answer/Explanation
(a)(i) 20
Total teeth = incisors + canines + pre-molars + molars.
Total = \(8 + 0 + 6 + 6 = 20\).
(a)(ii) Sheep have the same number of pre-molar and molar teeth; A human has twice the number of molar teeth as a sheep
Sheep have 6 pre-molars and 6 molars, so these are equal.
Humans have 12 molars, which is exactly twice the 6 molars sheep have.
Sheep do not have canine teeth, and humans and sheep both have 8 incisors, so the other statements are incorrect.
(b) Incisor — cut food; Canine — pierce and tear food; Pre-molar — grind food; Molar — grind food
Incisors have sharp, flat edges suited for cutting food.
Canines are pointed and used to pierce and tear food.
Both pre-molars and molars have broad, ridged surfaces used for grinding food, so they share the same function.
(c) Dentine; enamel
Enamel is the hard, outermost layer covering the crown of the tooth.
Dentine lies beneath the enamel and forms the bulk of the tooth structure.
(d) Mechanical (digestion)
Teeth break food down into smaller pieces by physical action.
This is mechanical digestion, as it does not involve chemical breakdown of molecules.
Question 8
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topics C11.2, C11.3 — Naming organic compounds, Fuels (Part (a))
• Topic C11.6 — Alcohols (Part (b))
• Topic C11.1 — Formulas and terminology (Part (c))
• Topic C11.3 — Fuels (Part (d))
• Topic C11.6 — Alcohols (Part (e))
▶️ Answer/Explanation
(a) Process X — fractional distillation; Process Y — cracking
Fractional distillation separates crude petroleum into fractions, including the diesel fraction.
Cracking breaks down the larger diesel-fraction molecules into smaller molecules, including ethene.
(b) Steam
Ethene reacts with steam under high pressure in the presence of a catalyst.
This process is called hydration and produces ethanol.
(c) Ethene contains only carbon and hydrogen atoms
A hydrocarbon is a compound made up of carbon and hydrogen atoms only.
Ethene, \(\text{C}_2\text{H}_4\), fits this definition exactly.
(d) Carbon dioxide; water
Complete combustion of a hydrocarbon in excess oxygen produces carbon dioxide and water.
These are the only two products when combustion is complete.
(e)
Ethanol, \(\text{C}_2\text{H}_5\text{OH}\), has two carbon atoms joined by a single bond.
Each carbon carries the appropriate number of hydrogen atoms, and the \(-\text{O}-\text{H}\) group is attached to one of the carbon atoms.
Question 9
Calculate the resultant upward force on the rocket.
Calculate the average speed of the rocket in \(\text{km/s}\).
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.5.1 — Effects of forces (Parts (a)(i), (a)(ii))
• Topic P1.2 — Motion (Part (a)(iii))
• Topic P3.2.3 — Thin converging lens (Parts (b)(i), (b)(ii))
• Topic P3.2.2 — Refraction of light (Part (b)(iii))
• Topic P3.3 — Electromagnetic spectrum (Parts (c)(i), (c)(ii))
• Topic P3.4 — Sound (Part (c)(iii))
▶️ Answer/Explanation
(a)(i) 4 000 000 N
Resultant force = upward force − weight.
Resultant force = \(12{,}000{,}000 – 8{,}000{,}000 = 4{,}000{,}000 \, \text{N}\) upward.
(a)(ii) The rocket would not move/take off
If the resultant force were zero, the forces on the rocket would be balanced.
With no resultant force, the rocket could not accelerate upward and would remain stationary.
(a)(iii) 1.43 km/s
Convert 75 hours to seconds: \(75 \times 3600 = 270{,}000 \, \text{s}\).
Speed = distance ÷ time = \(\dfrac{385{,}000}{270{,}000} \approx 1.43 \, \text{km/s}\).
(b)(i)/(ii) Principal focus and focal length correctly identified
The principal focus, F, is the point where the parallel light rays converge after passing through the lens.
The focal length is the distance from the centre of the lens to this principal focus, shown by the double-headed arrow.
(b)(iii) Refraction
Light changes direction as it passes from air into the glass lens, and again as it leaves the lens.
This bending of light at a boundary between two different media is called refraction.
(c)(i) γ-rays, ultraviolet, infrared, radio waves (radio waves placed after infrared)
The electromagnetic spectrum is ordered by wavelength/frequency: gamma, ultraviolet, infrared, then radio waves.
Radio waves have the longest wavelength and are placed at the end of the sequence shown.
(c)(ii) γ-rays
Frequency increases as wavelength decreases across the electromagnetic spectrum.
Gamma rays have the shortest wavelength, so they have the greatest frequency.
(c)(iii) There is no medium (vacuum) in space, so there are no particles to transfer the vibrations
Sound waves are mechanical waves and need a medium of particles to travel through.
Space is a vacuum, so there are no particles present to carry the vibrations from the rocket to Earth.
Question 10
- circle the part where pollination occurs,
- draw an X on the part where fertilisation occurs,
- identify one part that produces pollen with a label line and the correct name.
Fertilisation occurs in the ovary / oviduct / vagina.
The nuclei of a sperm and egg fuse to form a gamete / tissue / zygote.
The fertilised cell divides into a ball of cells called an embryo / organ / ovule.
The ball of cells implants into the wall of the cervix / uterus / vagina.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B15.3 — Sexual reproduction in plants (Parts (a)(i), (a)(ii), (a)(iii))
• Topic B15.4 — Sexual reproduction in humans (Part (b))
▶️ Answer/Explanation
(a)(i) Circle around stigma; X on ovule; label line to anther
Pollination occurs when pollen lands on the stigma, so the stigma is circled.
Fertilisation occurs when the pollen nucleus fuses with the egg nucleus inside the ovule, so an X is placed there.
The anther is the part of the stamen that produces pollen.
(a)(ii) Style; stigma (or ovary)
The carpel is the female reproductive structure of the flower.
It is made up of the stigma, style, and ovary.
(a)(iii) Attract pollinators/insects for pollination
Petals are often brightly coloured and scented in insect-pollinated flowers.
This attracts insects to the flower, helping to bring about pollination.
(b) Oviduct; zygote; embryo; uterus
Fertilisation occurs in the oviduct, where the sperm meets the egg.
The fused nuclei form a zygote, which divides repeatedly to form a ball of cells called an embryo.
This embryo then implants into the wall of the uterus.
Question 11
After a short time, the bromine gas spreads out to fill the gas jar.
This process is called diffusion.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic C1.2 — Diffusion (Part (a))
• Topic C8.3 — Group VII properties (Part (b))
• Topic C8.1 — Arrangement of elements (Part (c))
• Topic C10.1 — Water (Part (d))
• Topic C2.5 — Simple molecules and covalent bonds (Parts (e), (f)(ii))
• Topic C3.1 — Formulas (Part (f)(i))
▶️ Answer/Explanation
(a) Gas particles are in constant random motion; particles move from a region of high concentration to a region of low concentration
Bromine particles move randomly and continuously due to their kinetic energy.
They spread from the area where they are highly concentrated to areas of lower concentration until evenly distributed.
(b) Iodine (or fluorine or astatine)
Chlorine and bromine belong to Group VII, the halogens.
Other halogens in this group include fluorine, iodine, and astatine.
(c) Metallic character decreases from left to right across Period 3
Elements on the left side of Period 3, such as sodium and magnesium, are metals.
Moving across the period, elements become progressively less metallic and more non-metallic, such as chlorine and argon.
(d) To kill microorganisms/bacteria/pathogens
Chlorine is added to drinking water as a disinfectant.
It kills harmful microorganisms and pathogens, making the water safe to drink.
(e) Shared pair of electrons; correct number of electrons shown (14 electrons in total)
Each chlorine atom contributes one electron to a shared pair, forming a single covalent bond.
Each chlorine atom also has three additional lone pairs of outer shell electrons, giving 14 electrons in total across the molecule.
(f)(i) 2 HCl
The equation must be balanced so the number of atoms of each element is equal on both sides.
\(\text{H}_2 + \text{Cl}_2 \rightarrow 2\text{HCl}\).
(f)(ii) Two non-metals bonding; shared pair of electrons
Hydrogen and chlorine are both non-metal elements.
When two non-metals bond, they share electrons to form a covalent bond rather than transferring electrons as in ionic bonding.
Question 12
Position Q shows ………………………………. air.
This method of thermal energy transfer is called ………………………………. .
Box Y shows the arrangement of particles in a liquid.
Solidification occurs when a …………………………….. turns into a …………………………….. .
Condensation occurs when a …………………………….. turns into a …………………………….. .
Calculate the resistance of the lamp.
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P2.3.4 — Consequences of thermal energy transfer (Part (a))
• Topic P2.1.1 — States of matter (Parts (b)(i), (b)(ii))
• Topic P2.2.2 — Melting, boiling and evaporation (Part (b)(iii))
• Topic P4.3.1 — Circuit diagrams and circuit components (Part (c)(i))
• Topic P4.2.4 — Resistance (Part (c)(ii))
▶️ Answer/Explanation
(a) Position P — cooled air; Position Q — warmed air; convection
Air near the heater at Q is warmed, becomes less dense, and rises.
As it circulates and loses heat, it cools at P and sinks back down.
This transfer of thermal energy through the movement of a fluid is called convection.
(b)(i) Random arrangement and widely spaced particles
In a gas, particles are far apart and move randomly at high speed.
Box Z should show widely spaced particles with no regular arrangement.
(b)(ii) Solidification: liquid → solid; Condensation: gas → liquid
Solidification occurs when a liquid loses energy and turns into a solid.
Condensation occurs when a gas loses energy and turns into a liquid.
(b)(iii) Melting point = 0 °C; boiling point = 100 °C
At standard atmospheric pressure, water melts (freezes) at \(0\,^\circ\text{C}\).
Water boils at \(100\,^\circ\text{C}\) under the same conditions.
(c)(i) Ammeter; voltmeter
The circular symbol with “A” represents an ammeter, which measures current.
The circular symbol with “V” represents a voltmeter, which measures potential difference.
(c)(ii) 20 Ω
Resistance = potential difference ÷ current.
\(R = \dfrac{V}{I} = \dfrac{6}{0.3} = 20 \, \Omega\).