Science: Full Practice Paper 13 Worksheet with Answers

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CE.S-T13 Science: Full Practice Paper 13

ISEB COMMON ENTRANCE CE.S-T13 · Calculator allowed · about 60 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

1

Which part of a plant cell controls the cell's activities and contains most of its genetic material (DNA)?

A) Cell wall
B) Nucleus
C) Vacuole
D) Chloroplast

(Total for Question 1 is 1 mark)

2

Which bone in the human skeleton protects the brain?

A) Cranium (skull)
B) Femur
C) Sternum
D) Radius

(Total for Question 2 is 1 mark)

3

Complete the two missing words in these sentences about blood vessels.

(a)Blood vessels that carry blood away from the heart, usually under high pressure, are called ______.(1)

(b)Blood vessels that carry blood back to the heart, usually under low pressure, are called ______.(1)

(Total for Question 3 is 2 marks)

4

Which food test uses Benedict's solution and requires heating to detect a positive result (a colour change from blue to orange or brick-red)?

A) Test for starch
B) Test for reducing sugar
C) Test for protein
D) Test for fat

(Total for Question 4 is 1 mark)

5

Grace investigates osmosis using potato chips. She cuts five identical potato chips, weighs each one, then places one chip into each of five beakers containing sugar solution of a different concentration. After 24 hours she removes each chip, dries it, and reweighs it, calculating the percentage change in mass.

Concentration of sugar solution (mol/dm3): 0.0	0.2	0.4	0.6	0.8
Percentage change in mass (%): +12	+5	-2	-9	-15

(a)Identify the independent variable in Grace's investigation.(1)

(b)State one variable that Grace kept the same to make this a fair test.(1)

(c)Describe the pattern shown by the results.(1)

(d)Explain, in terms of osmosis, why the potato chip in the 0.8 mol/dm3 solution lost mass.(1)

(Total for Question 5 is 4 marks)

6

Describe the main job of each of these three organs in the human digestive system: the stomach, the small intestine, and the large intestine.

(Total for Question 6 is 3 marks)

7

A student measures the length of a plant cell in a microscope image as 45 mm. The image has been magnified 300 times (x300). Calculate the actual length of the cell in micrometres (um). (1 mm = 1000 um)

(Total for Question 7 is 2 marks)

8

Oliver investigates how temperature affects the growth of mould on bread. He places an identical, slightly damp slice of bread into five sealed bags, and stores one bag at each of five different temperatures for one week. He then estimates the percentage of each bread slice's surface covered by mould.

Storage temperature (deg C): 4	12	20	28	36
Surface covered by mould (%): 2	15	45	70	30

(a)Identify the independent variable in Oliver's investigation.(1)

(b)State one variable that Oliver kept the same to make this a fair test.(1)

(c)Describe the pattern shown by the results.(1)

(d)Explain why mould coverage was lower at 36 deg C than at 28 deg C.(1)

(Total for Question 8 is 4 marks)

9

Cigarette smoke contains many harmful substances, including tar and carbon monoxide, and damages the structures inside the lungs used for gas exchange.

(a)State the name of the tiny air sacs in the lungs where gas exchange takes place.(1)

(b)State one feature of the alveoli that makes them well adapted for efficient gas exchange.(1)

(c)Explain how smoking damages the alveoli, and the effect this has on gas exchange.(1)

(d)Explain why carbon monoxide in cigarette smoke is dangerous to a smoker's health.(1)

(Total for Question 9 is 4 marks)

10

Cystic fibrosis is a genetic disorder caused by a recessive allele. Two parents, neither of whom has cystic fibrosis, have a child who is born with cystic fibrosis. Explain how this is possible, using ideas about alleles and inheritance.

(Total for Question 10 is 6 marks)

11

Which subatomic particle has a negative charge and is found orbiting the nucleus of an atom?

A) Proton
B) Neutron
C) Electron
D) Nucleon

(Total for Question 11 is 1 mark)

12

In which state of matter are the particles arranged in a fixed, regular pattern and only vibrate about fixed positions?

A) Solid
B) Liquid
C) Gas
D) Plasma

(Total for Question 12 is 1 mark)

13

Complete the two missing words in these sentences about separation techniques.

(a)The process of separating a soluble solid from a solution by heating the solution so that the liquid turns to gas, leaving the solid behind, is called ______.(1)

(b)The process of separating the different coloured substances in a mixture, such as ink, using a solvent moving up absorbent paper, is called ______.(1)

(Total for Question 13 is 2 marks)

14

Which part of the periodic table contains the most reactive metals, such as lithium, sodium and potassium?

A) Group 0
B) Group 1
C) Group 7
D) The transition metals

(Total for Question 14 is 1 mark)

15

Priya investigates the conditions needed for iron nails to rust. She places an identical iron nail into each of four test tubes, set up as follows, and checks each nail for rust after one week.

Tube 1: nail in air only (dry, with a drying agent, tube sealed)
Tube 2: nail in boiled, air-free water, with a layer of oil on top to keep out air
Tube 3: nail in water, exposed to air
Tube 4: nail in salt water, exposed to air
Amount of rust after one week: Tube 1 - none | Tube 2 - none | Tube 3 - some rust | Tube 4 - much more rust

(a)Identify the independent variable in Priya's investigation.(1)

(b)State one variable that Priya kept the same to make this a fair test.(1)

(c)Using the results, state the two substances that must both be present for iron to rust.(1)

(d)Explain why the nail in salt water (Tube 4) rusted more than the nail in plain water (Tube 3).(1)

(Total for Question 15 is 4 marks)

16

5.4 g of magnesium reacts completely with oxygen to form 9.0 g of magnesium oxide. Calculate the mass of oxygen that reacted, using the law of conservation of mass.

(Total for Question 16 is 2 marks)

17

Write a word equation for each of these reactions: methane burning completely in oxygen; magnesium reacting with hydrochloric acid; and calcium carbonate breaking down when heated (thermal decomposition).

(Total for Question 17 is 3 marks)

18

When solid ammonium nitrate is dissolved in water, the temperature of the mixture decreases. When solid calcium oxide is added to water, the temperature of the mixture increases.

(a)State the term used to describe a reaction in which the surroundings decrease in temperature (energy is taken in from the surroundings).(1)

(b)State the term used to describe a reaction in which the surroundings increase in temperature (energy is given out to the surroundings).(1)

(c)Explain, in terms of energy transfer, why the temperature falls when ammonium nitrate dissolves in water.(1)

(d)Suggest one practical use of a reaction that takes in energy from its surroundings, like the ammonium nitrate reaction.(1)

(Total for Question 18 is 4 marks)

19

Complete the three missing words in these sentences about acids and bases.

(a)A substance that reacts with an acid to form a salt and water only, often a metal oxide or metal hydroxide, is called a ______.(1)

(b)A base that is soluble in water is more specifically called a(n) ______.(1)

(c)The salt formed when hydrochloric acid reacts with a base always belongs to the ______ family of salts.(1)

(Total for Question 19 is 3 marks)

20

Molten lead bromide (PbBr2) conducts electricity and can be broken down into its elements, lead and bromine, by electrolysis. Explain, using ideas about ions, how electrolysis separates molten lead bromide into lead and bromine.

(Total for Question 20 is 6 marks)

21

Which quantity is defined as force per unit area, and is measured in pascals (Pa)?

A) Density
B) Pressure
C) Momentum
D) Work done

(Total for Question 21 is 1 mark)

22

Which piece of equipment is used to measure electric current in a circuit, and must be connected in series?

A) Voltmeter
B) Ammeter
C) Thermometer
D) Newton meter

(Total for Question 22 is 1 mark)

23

Complete the two missing words in these sentences about magnetism.

(a)A magnetic material that is attracted to a magnet but does not stay magnetised once the magnet is removed is described as a ______ magnetic material.(1)

(b)The region around a magnet where a magnetic force can be detected is called the magnetic ______.(1)

(Total for Question 23 is 2 marks)

24

Kofi investigates how the number of turns of wire wrapped around an iron nail affects the strength of the electromagnet he makes. He wraps a different number of turns of insulated wire around an identical iron nail each time, connects it to the same battery, and counts how many small paperclips the electromagnet can pick up.

Number of turns of wire: 10	20	30	40
Number of paperclips picked up: 3	6	10	13

(a)Identify the independent variable in Kofi's investigation.(1)

(b)State one variable that Kofi kept the same to make this a fair test.(1)

(c)Describe the pattern shown by the results.(1)

(d)Predict the number of paperclips the electromagnet would pick up with 50 turns of wire, and explain your prediction.(1)

(Total for Question 24 is 4 marks)

25

A uniform seesaw is balanced on a central pivot. A child of weight 300 N sits 2 m from the pivot on one side.

(a)State the equation (formula) that relates moment, force and distance.(1)

(b)Calculate the distance from the pivot at which a second child of weight 400 N must sit on the other side, so that the seesaw balances.(2)

(Total for Question 25 is 3 marks)

26

Describe what happens to light when it: reflects off a plane (flat) mirror; refracts when passing from air into glass; and is dispersed by a glass prism.

(Total for Question 26 is 3 marks)

27

Two identical bulbs can be connected to the same battery either in series or in parallel.

(a)State what happens to the current at any point around a series circuit (containing just one loop).(1)

(b)State how the current from the battery splits when it reaches a junction in a parallel circuit.(1)

(c)Explain why adding a second identical bulb in series with the first bulb makes both bulbs dimmer than a single bulb on its own.(1)

(d)Explain why adding a second identical bulb in parallel (as a new branch) does not make the first bulb dimmer.(1)

(Total for Question 27 is 4 marks)

28

Freya investigates how the length of a piece of resistance wire affects its resistance. She connects different lengths of the same wire into a circuit with a battery, an ammeter and a voltmeter, and calculates the resistance for each length using resistance = potential difference / current.

Length of wire (cm): 10	20	30	40
Resistance (ohms): 2.1	4.0	6.2	8.1

(a)Identify the independent variable in Freya's investigation.(1)

(b)State one variable that Freya kept the same to make this a fair test.(1)

(c)Describe the pattern shown by the results.(1)

(d)Use the results to predict the resistance of a 50 cm length of the same wire.(1)

(Total for Question 28 is 4 marks)

29

A metal block has a mass of 316 g and a volume of 40 cm3. Calculate the density of the metal, using density = mass / volume, giving your answer in g/cm3.

(Total for Question 29 is 2 marks)

30

Electricity is transmitted from power stations to homes through the National Grid at a very high voltage (and correspondingly low current), using step-up and step-down transformers. Explain why transmitting electricity at a high voltage and low current, rather than a low voltage and high current, makes the National Grid more efficient.

(Total for Question 30 is 6 marks)

Mark scheme · CE.S-T13 Science: Full Practice Paper 13

Question 1

B1 B cao
Answer: B) Nucleus

Question 2

B1 A cao
Answer: A) Cranium (skull)

Question 3

(a) B1 arteries cao
(a) Answer: Arteries
(b) B1 veins cao
(b) Answer: Veins

Question 4

B1 B cao
Answer: B) Test for reducing sugar

Question 5

(a) B1 the concentration of the sugar solution oe
(a) Answer: The concentration of the sugar solution.
(b) B1 any one of: the starting size/mass of the potato chips; the volume of solution used; the time left in the solution (24 hours); the type/variety of potato used; the temperature oe
(b) Answer: For example, the starting size (mass) of each potato chip.
(c) B1 as the concentration of sugar solution increases, the percentage change in mass decreases, from a gain in mass at low concentrations to a loss in mass at higher concentrations oe
(c) Answer: As the concentration of sugar solution increases, the percentage change in mass decreases, from a gain in mass at low concentrations to a loss in mass at higher concentrations.
(d) B1 the sugar solution outside the chip has a lower water concentration than the solution inside the potato cells, so water moves out of the cells, across the partially permeable cell membrane, from a high to a low water concentration, by osmosis oe
(d) Answer: The sugar solution outside the chip has a lower water concentration than inside the potato cells, so water moves out of the cells, across the partially permeable membrane, by osmosis, from a high to a low water concentration.

Question 6

B1 the stomach churns food and mixes it with acid and protease enzymes, beginning the chemical digestion of protein, and kills many harmful bacteria oe
B1 the small intestine is where most chemical digestion is completed (using enzymes from the pancreas and gut wall) and where most digested food (nutrients) is absorbed into the blood, mainly through villi oe
B1 the large intestine absorbs excess water from the undigested remains of food, producing solid faeces oe
Answer: The stomach churns food, adds acid and protease enzymes, and begins digesting protein. The small intestine completes digestion and absorbs most nutrients into the blood. The large intestine absorbs excess water, producing solid faeces.

Question 7

M1 correct substitution: actual length = 45 / 300 (= 0.15 mm) oe
A1 150 um cao
Answer: 150 um

Question 8

(a) B1 the storage temperature oe
(a) Answer: The storage temperature.
(b) B1 any one of: the type/size of bread slice used; the amount of moisture (dampness) added; the size/type of bag used; the length of time the bread was stored (1 week) oe
(b) Answer: For example, the type and size of bread slice used.
(c) B1 mould coverage increases as temperature rises from 4 to 28 deg C, but decreases at 36 deg C (compared with 28 deg C) oe
(c) Answer: Mould coverage increases as temperature rises from 4 to 28 deg C, but decreases at 36 deg C compared with 28 deg C.
(d) B1 36 deg C is above the optimum temperature for the mould's growth; at temperatures this high the enzymes controlling its growth begin to denature (or its rate of growth/reproduction is reduced), so less mould grows than at 28 deg C oe
(d) Answer: 36 deg C is above the optimum temperature for this mould; at such high temperatures the enzymes controlling its growth begin to denature, so less mould grows than at 28 deg C.

Question 9

(a) B1 alveoli cao
(a) Answer: Alveoli
(b) B1 any one of: large (total) surface area, because there are millions of alveoli; walls are very thin (one cell thick), giving a short diffusion distance; a good (dense) blood supply from capillaries, maintaining a steep concentration gradient; a moist lining, allowing gases to dissolve oe
(b) Answer: For example, alveoli have a very large total surface area because there are millions of them.
(c) B1 tar and other chemicals in smoke damage/break down the walls of the alveoli, reducing their surface area, which reduces the rate of gas exchange (less oxygen absorbed, less carbon dioxide removed), causing breathlessness oe
(c) Answer: Tar and other chemicals in smoke damage the walls of the alveoli, reducing their surface area, which reduces the rate of gas exchange and causes breathlessness.
(d) B1 carbon monoxide binds to haemoglobin in red blood cells more readily/permanently than oxygen does (forming carboxyhaemoglobin), reducing the amount of oxygen the blood can carry around the body oe
(d) Answer: Carbon monoxide binds to haemoglobin in red blood cells more readily than oxygen, reducing the amount of oxygen the blood can carry around the body.

Question 10

Level 1 (1-2): Basic, isolated statement(s) about genes or alleles, with little or no reference to how two unaffected parents can have an affected child.
Level 2 (3-4): Some relevant ideas about recessive alleles or carriers are given, but the explanation of how both parents pass on the allele to produce an affected child is incomplete or not fully linked.
Level 3 (5-6): A clear, logically linked explanation that both parents are carriers (heterozygous, with one dominant and one recessive allele each), showing no symptoms because the dominant allele masks the recessive one, but each can pass on the recessive allele, and a child inheriting the recessive allele from both parents is homozygous recessive and has the disorder.
Indicative content:
- The allele for cystic fibrosis is recessive, so a person only has the disorder if they inherit a copy of the recessive allele from both parents (they are homozygous recessive).
- A person with one dominant (healthy) allele and one recessive (cystic fibrosis) allele is called a carrier; they do not have the disorder themselves because the dominant allele is expressed, masking the effect of the recessive allele.
- Both parents in this family must be carriers, each having one dominant allele and one recessive allele, which is why neither parent has cystic fibrosis themselves.
- When each parent produces gametes (sex cells), each gamete carries only one of the two alleles; there is a chance that any one gamete carries the recessive allele.
- If the child inherits the recessive allele from both the mother's egg cell and the father's sperm cell, the child will be homozygous recessive and so will have cystic fibrosis.
- This can be shown using a genetic (Punnett square) diagram: if both parents are Ff (carriers), on average 1 in 4 (25%) of their children would be expected to be ff and have cystic fibrosis, 2 in 4 would be carriers (Ff) like their parents, and 1 in 4 would be FF (neither carrier nor affected).

Question 11

B1 C cao
Answer: C) Electron

Question 12

B1 A cao
Answer: A) Solid

Question 13

(a) B1 evaporation cao
(a) Answer: Evaporation
(b) B1 chromatography cao
(b) Answer: Chromatography

Question 14

B1 B cao
Answer: B) Group 1

Question 15

(a) B1 the conditions the nail was kept in (i.e. the presence of water and/or air) oe
(a) Answer: The conditions the nail was kept in (the presence of water and/or air).
(b) B1 any one of: the type/size of iron nail used; the length of time (1 week); the type/size of test tube used oe
(b) Answer: For example, the type and size of iron nail used.
(c) B1 water and oxygen (from the air), both needed oe (must give both for the mark)
(c) Answer: Water and oxygen (from the air).
(d) B1 salt water contains dissolved ions, which speeds up (increases the rate of) the rusting reaction compared with plain water, even though both have water and air present oe
(d) Answer: Salt water contains dissolved ions, which speeds up the rusting reaction compared with plain water.

Question 16

M1 correct approach: mass of oxygen = mass of magnesium oxide - mass of magnesium oe
A1 3.6 g cao
Answer: 3.6 g

Question 17

B1 methane + oxygen -> carbon dioxide + water oe
B1 magnesium + hydrochloric acid -> magnesium chloride + hydrogen oe
B1 calcium carbonate -> calcium oxide + carbon dioxide oe
Answer: methane + oxygen -> carbon dioxide + water; magnesium + hydrochloric acid -> magnesium chloride + hydrogen; calcium carbonate -> calcium oxide + carbon dioxide.

Question 18

(a) B1 endothermic cao
(a) Answer: Endothermic
(b) B1 exothermic cao
(b) Answer: Exothermic
(c) B1 the process is endothermic, taking in more energy from the surroundings (the water) than it releases; as the surroundings lose thermal energy, their temperature falls oe
(c) Answer: The process is endothermic, taking in more energy from the water than it releases, so the water loses thermal energy and its temperature falls.
(d) B1 any suitable practical use, e.g. instant cold packs used to treat sports injuries oe
(d) Answer: For example, instant cold packs used to treat sports injuries.

Question 19

(a) B1 base cao
(a) Answer: Base
(b) B1 alkali cao
(b) Answer: Alkali
(c) B1 chloride cao
(c) Answer: Chloride

Question 20

Level 1 (1-2): Basic, isolated statement(s) about ions or electrodes, with little or no reference to how the elements are formed at each electrode.
Level 2 (3-4): Some relevant ideas about ions moving to electrodes or gaining/losing electrons are given, but the explanation of what forms at each electrode, and why, is incomplete or not fully linked.
Level 3 (5-6): A clear, logically linked explanation that molten lead bromide contains free-moving positive lead ions and negative bromide ions, which move to and are discharged at opposite electrodes by gaining or losing electrons, forming lead at the cathode and bromine at the anode.
Indicative content:
- Molten lead bromide contains lead ions (Pb2+) and bromide ions (Br-), which are free to move because the solid lattice has melted.
- When a current is passed through the molten compound, the positive lead ions (Pb2+) are attracted to, and move towards, the negative electrode (cathode).
- At the cathode, each lead ion gains two electrons (is reduced) to form a lead atom; molten lead collects at the cathode.
- The negative bromide ions (Br-) are attracted to, and move towards, the positive electrode (anode).
- At the anode, each bromide ion loses one electron (is oxidised) to form a bromine atom; bromine atoms pair up to form bromine molecules (Br2), seen as an orange/brown gas or vapour released at the anode.
- The ionic compound is split into its two separate elements, lead and bromine, one forming at each electrode, because oppositely charged ions are attracted to and discharged at opposite electrodes.

Question 21

B1 B cao
Answer: B) Pressure

Question 22

B1 B cao
Answer: B) Ammeter

Question 23

(a) B1 soft (e.g. soft iron) cao
(a) Answer: Soft (e.g. soft iron)
(b) B1 field cao
(b) Answer: Field

Question 24

(a) B1 the number of turns of wire (wrapped around the nail) oe
(a) Answer: The number of turns of wire wrapped around the nail.
(b) B1 any one of: the iron nail used (its size/type); the battery or current used; the size/type of paperclips used oe
(b) Answer: For example, the same iron nail (size and type) was used each time.
(c) B1 as the number of turns of wire increases, the number of paperclips picked up (the strength of the electromagnet) increases oe
(c) Answer: As the number of turns of wire increases, the number of paperclips picked up (the strength of the electromagnet) increases.
(d) B1 an answer in the range 15-18, with reasoning based on continuing the pattern of the results (e.g. the number of paperclips increases by roughly 3-4 for every extra 10 turns) oe; allow follow-through from a sensible extrapolation of the data
(d) Answer: Approximately 16-17 paperclips (accept 15-18), following the trend of the data.

Question 25

(a) B1 moment = force x distance (from the pivot) cao
(a) Answer: Moment = force x distance (from the pivot).
(b) M1 correct substitution: 400 x d = 300 x 2 oe
(b) A1 1.5 m cao
(b) Answer: 1.5 m

Question 26

B1 reflection: the light ray bounces off the mirror surface, obeying the law of reflection (the angle of incidence equals the angle of reflection) oe
B1 refraction: the light ray changes direction (bends towards the normal) as it passes from air into the denser glass, because it changes speed (slows down) oe
B1 dispersion: white light passing through a glass prism is split up into the colours of the spectrum, because different colours (wavelengths) of light are refracted by different amounts oe
Answer: Reflection: the light bounces off the mirror, with the angle of incidence equal to the angle of reflection. Refraction: the light bends towards the normal as it slows down entering the glass. Dispersion: white light is split into the colours of the spectrum because different colours refract by different amounts.

Question 27

(a) B1 the current is the same at every point in the (series) circuit oe
(a) Answer: The current is the same at every point in the circuit.
(b) B1 the current splits between the branches at the junction; the total current entering a junction equals the total current leaving it oe
(b) Answer: The current splits between the branches at the junction; the total current in equals the total current out.
(c) B1 adding a second bulb in series increases the total resistance of the circuit, decreasing the current for the same battery voltage; the battery's voltage is also shared between the two bulbs rather than being all across one, so each bulb is dimmer oe
(c) Answer: Adding a second bulb in series increases the total resistance, decreasing the current, and the battery voltage is shared between the two bulbs rather than being all across one, so each bulb is dimmer.
(d) B1 in parallel, each branch is connected directly across the full potential difference of the battery, so the first bulb still has the same voltage across it and the same current through it as before, so its brightness is unaffected oe
(d) Answer: In parallel, each bulb is connected directly across the full battery voltage, so the first bulb still has the same voltage and current as before, and its brightness is unaffected.

Question 28

(a) B1 the length of the wire oe
(a) Answer: The length of the wire.
(b) B1 any one of: the type/material of the wire used; the thickness (diameter/cross-sectional area) of the wire; the temperature of the wire oe
(b) Answer: For example, the type and thickness of wire used.
(c) B1 as the length of the wire increases, its resistance increases (roughly in direct proportion to length) oe
(c) Answer: As the length of the wire increases, its resistance increases, roughly in direct proportion to length.
(d) B1 an answer in the range 9.8-10.5 ohms, with reasoning based on continuing the trend of the data (e.g. resistance increases by about 2 ohms for every extra 10 cm) oe
(d) Answer: Approximately 10.0-10.2 ohms (accept 9.8-10.5 ohms), following the trend of the data.

Question 29

M1 correct substitution: density = 316 / 40 oe
A1 7.9 g/cm3 cao
Answer: 7.9 g/cm3

Question 30

Level 1 (1-2): Basic, isolated statement(s) about transformers, voltage or current, with little or no reference to how energy is wasted in the cables.
Level 2 (3-4): Some relevant ideas about lower current or reduced heating are given, but the explanation linking current to the amount of energy wasted as heat in the cables is incomplete or not fully linked.
Level 3 (5-6): A clear, logically linked explanation that step-up transformers increase the voltage and correspondingly decrease the current for the same power transmitted, and that because heating in the cables depends strongly on current, a lower current greatly reduces the energy wasted as heat, making transmission more efficient; step-down transformers then reduce the voltage to a safe level before reaching homes.
Indicative content:
- A step-up transformer at the power station increases the voltage of the electricity supply before it is transmitted through the National Grid cables.
- For a given amount of power being transmitted, increasing the voltage means the current in the cables is correspondingly much lower, since power = potential difference x current, so for constant power a higher voltage means a lower current.
- As electricity flows through the cables, some energy is wasted, transferred as heat, because the cables have resistance.
- The amount of energy wasted as heat in the cables increases sharply as current increases, so keeping the current low, by transmitting at high voltage, greatly reduces the amount of energy wasted.
- This means much more of the energy generated at the power station reaches homes and businesses usefully, rather than being wasted heating the cables, making the system more efficient and reducing the cost of the energy lost.
- Step-down transformers are then used near homes to reduce the very high transmission voltage down to a safer voltage, 230 V in the UK, suitable for use in houses.

Science: Full Practice Paper 13 - Worksheets, Questions and Revision

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CE.S-T13 Science: Full Practice Paper 13

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