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Ecology
Syllabus
OB59 Study a local habitat, using appropriate instruments and simple keys to show the variety and
distribution of named organisms
OB60 Understand that living things are affected by their environment and respond to changes that occur in
that environment, and understand that their numbers depend on the availability of food and the
presence or absence of other organisms
OB61 List examples of producers, decomposers and consumers in an ecosystem
OB62 Select a food chain and a food web from a named habitat and identify examples of adaptation,
competition and interdependence
OB63 Understand the importance of conservation, pollution and waste management to the environment,
and identify ways in which living things contribute to these, both individually and as a community
OB64 Consider and discuss how human activity affects the environment, both positively and negatively
(two examples in each case)
Student Notes
Habitat Study
To study a local habitat
Method 1. Make a map of the habitat- mark in any distinctive physical features e.g. streams, trees, ponds, rock,
paths etc.
2. Physical factors such as soil pH, temp., amount of sunlight and rainfall can be included.
3. Collect and identify plants/animals (using keys to identify various plants and animals).
Equipment used in a habitat study
Pitfall trap: collects small organisms that walk along the surface of the ground e.g. beetle, spiders,
centipedes.
Beating tray: e.g. a large cloth - for insects and spiders which fall off trees and shrubs.
Pooter: for small insects, spiders, mites from surfaces of leaves and leaf litter and for
transfer from beating trays and nets into containers.
Line transect: used to show the distribution of a species across an area e.g. from shade to
sun in a woodland - use rope with knots at 1 metre - record name and height of plant touching each mark.
Quadrats Used to measure how frequently a plant species occurs in a habitat.
A habitat is an environment where an organism lives, e.g. a hedge or a meadow
Ecology is the study of the interactions between organisms and their environment
2
Throw at random, > 10, identify and count plants as follows:
% Frequency = Number of quadrats in which ‘x’ found x 100
Total number of quadrats
Producers, consumers and decomposers
Examples: plants
Examples: herbivores, carnivores, omnivores.
Examples: bacteria and fungi.
Food Chains and Food Webs
All organisms need energy to live. Sun is the primary source of energy.
Energy flows from one organism to the next by means of a food chain.
Food Chain A food chain is a list of organisms in the order in which one is
eaten by the other.
Example of a food chain from a forest habitat
1st 2nd 3rd
(producer) (primary consumer) (secondary consumer)
Grass rabbit fox
Food Web
A food web consists of two or more interlinked food chains
A producer is an organism which makes its own food
A consumer is an organism which feeds off other organisms
A decomposer is a living organism that feeds on dead plants and animals
3
Adaptation, Competition and Interdependence in a food chain
Adaptation
Examples of adaptation in a rabbit
1. It is brown for camouflage.
2. Long ears so it can detect the presence of its predators.
Examples of adaptation in plants
1. Some plants have a nasty taste to deter predators e.g. giant hogweed.
2. Bracken can grow in shade, grass cannot.
Competition
Examples
Plants and animal compete for space, light, food, mate, water, minerals, shelter.
Interdependence
Example
A plant relies on an insect for pollination while the insect relies on the plant for food.
Trees depend on birds for seed dispersal and the birds get shelter, nests, nuts and berries in return.
Living things are affected by their environment and respond to changes that occur in that environment
The size of a population depends on the availability of food and the presence or absence of other organisms
Competition is the struggle between organisms for a resource that is in short supply
Interdependence is where two organisms rely on each other for some aspect of survival
Adaptation is the process where an organism becomes better suited to its environment
4
Looking after our environment; Pollution, Conservation and Waste Management
Pollution
Pollution is the process by which harmful substances are added to the environment by humans.
Examples
Soil pollution
Water pollution
Air pollution
Greenhouse effect
Conservation Conservation is the preservation of the earth’s natural resources for the future.
Examples
National parks
Hedgerow and bogland conservation
Listing of threatened species e.g. lizard, frog and stoat in Ireland
Zoos and wildlife parks – by breeding endangered species
Waste Management
Waste management involves managing the disposal of our waste products
Examples
Reduce, Reuse, Recycle campaign
Compost bin – vegetable peelings and garden waste.
Incineration
Two negative effects of humans on the environment
1. Air pollution
2. Habitat destruction (e.g. deforestation, overhunting, etc)
Two positive effects of humans on environment
1. Protection of endangered species
2. Tree planting
5
Exam Questions
Food Chain / Food Web
1. [2011 OL]
Choose the correct organism from the list on the right to complete the
food chain below.
2. [2009 OL]
The food chain relates to a garden
habitat.
Study it and answer the questions that
follow.
(i) Name a producer in this food chain.
(ii) Name a consumer in this food chain.
(iii)Explain how the removal of ladybirds would affect the greenfly population in this habitat.
3. [2008]
The diagram shows part of a food web from a mixed habitat with meadows,
streams and hedges.
A is a dragonfly, B is a grasshopper, C is a butterfly
D is a house fly, E1, E2 and E3 are plants.
(i) Write down a food chain from the food web shown.
(ii) Select an organism from this habitat or name another organism from a
habitat you have studied and state one adaptation that the organism has that
makes it suited to its habitat.
(iii)What is meant by competition in a habitat?
(iv) Give an example of interdependence from the food web shown.
4. [2011]
The diagram shows a simplified food web from a mixed
habitat.
Answer the following questions using only items from
the diagram above in your answers.
(i) Write a food chain with three members.
(ii) Decomposers are not shown in the diagram.
What should decomposers feed on?
(iii)Give one example of adaption.
(iv) Name two animals that might be in competition.
(v) What is meant by the term interdependence.
(vi) Give an example of interdependence.
6
Equipment
5. [2008 OL][2010 OL]
The piece of equipment drawn on the right is used in ecology.
(i) Name the piece of equipment.
(ii) Give one use for this piece of equipment.
6. [2009]
The study of a habitat requires the use of sampling instruments, as it is not possible to count every
individual organism living there.
A pupil and teacher are using a quadrat. The quadrat is placed randomly in a number of sites in the
habitat being studied.
(i) How is random sampling achieved when using a quadrat?
(ii) Give two different types of data collected (two different tasks performed) at each site in the habitat when
using the quadrat.
7. [2006 OL][2010 OL]
The piece of equipment drawn on the right is used in ecology.
(i) Name the piece of equipment.
(ii) Give one use of this piece of equipment.
8. [2007]
The diagram shows a pooter. Describe how to use a pooter.
9. [2009]
Line transects are also used to sample habitats.
(i) What is a line transect?
(ii) Describe how to sample a habitat using a line transect.
10. [2009]
A sweep net is used to collect small animals e.g. insects from vegetation in a habitat so that they can be
identified.
(i) Name a second item of equipment used to collect small animals for identification.
(ii) Draw a labelled diagram, in the box provided, of the item that you have named in (i) above.
(iii)Describe how to use the item that you have named and drawn.
11. [2011 OL]
(i) Draw a diagram of a piece of equipment used by you to collect or trap insects or small animals when you
were studying a habitat.
(ii) Name the piece of equipment.
(iii)Explain how it was set up or used.
12. [2009]
Give two reasons why the groups of organisms living together can vary greatly from one part of a habitat
to another.
13. [2010]
The diagram shows a stickleback, a small fish that lives in our fresh water
habitats. Give two adaptations that fish have to help them to live in water.
14. [2008]
The photograph of ‘spaceship earth’ was taken by a member of the crew of Apollo 17.
Give two ways in which we can care for our planet.
7
15. [2011][2006]
Waste management includes: composting, incineration, landfill and recycling.
Pick two of the underlined methods of managing waste and say how it works and give
one advantage and one disadvantage of using the method that you have selected.
16. [2007]
The increase in carbon dioxide
concentration in the Earth’s atmosphere is
currently causing concern.
The use of fossil fuels and deforestation
have been identified as major contributors
to this increase in carbon dioxide
concentration. The graph shows a continual
increase in the carbon dioxide concentration
for the last fifty years. The data was
collected at a site in Europe.
(i) Explain how either the use of fossil fuels or
deforestation could have contributed to the
increase in atmospheric carbon dioxide.
(ii) Suggest one possible effect of continued
increase in carbon dioxide concentration in the Earth’s atmosphere.
(iii)Though there is an overall increase in carbon dioxide concentration there is an annual rise and fall in
carbon dioxide concentration as shown in the box in the diagram.
Suggest one reason why the carbon dioxide concentration decreases between April and October each
year.
(iv) How could the reason that you have given in (iii) be used in a practical way to slow down and even
reverse the overall increase in carbon dioxide levels in the atmosphere?
Questions
1. What is ecology?
2. What is a producer? Give two examples.
3. What is a decomposer? Give two examples.
4. What is a consumer? Give two examples.
5. List a habitat which you have studied and identify a food chain and a food web from it.
6. Identify examples of adaptation, competition and interdependence from the habitat you mentioned
above.
7. Why do organisms need to compete with each other?
8. What is (i) a herbivore, (ii) a carnivore, (iii) an omnivore? Give an example of each
8
Respiration
Syllabus
OB9 Describe the process of aerobic respiration by means of a word equation and understand that aerobic
respiration requires the presence of oxygen
OB10 Demonstrate the products of aerobic respiration
OB11 Carry out qualitative tests to compare the carbon dioxide levels of inhaled and exhaled air
OB12 Describe how oxygen is taken into the bloodstream from the lungs and how carbon dioxide is taken into the
lungs from the bloodstream during gaseous exchange and how these processes are affected by smoking
Student Notes
Respiration
Respiration is not the same as breathing!!
Respiration can be either aerobic or anaerobic.
Aerobic respiration requires oxygen while anaerobic does not.
Humans and all other animals carry out aerobic respiration while many micro-organisms like yeast carry out anaerobic
respiration
Equation for aerobic respiration
Test for CO2
It turns limewater milky.
Test for water
It turns cobalt chloride paper from blue to pink / it turns anhydrous copper sulphate from white to blue.
To show that there is more carbon dioxide in exhaled air than in inhaled air.
1. Suck air in through the position shown on diagram A
and note that the limewater takes a long time before
going milky.
2. Replace the limewater and this time exhale air
through the top of the tube as shown in diagram B
and note that the limewater goes milky quickly.
3. Conclusion: there is more carbon dioxide in exhaled
air.
Glucose + oxygen → Energy + carbon dioxide + water
Respiration is the controlled release of energy from food
9
How does air enter and leave the lungs?
1. The diaphragm contracts (this is you ‘sucking up’), pulling the
ribcage down.
2. The ribcage is attached to the lungs and as a result air is taken in
when the mouth (or nasal passage) is open.
3. In order to exhale, the diaphragm relaxes, pushing the ribcage
up so if the mouth is open air will escape.
Gaseous exchange:
How oxygen is taken into the bloodstream and carbon dioxide
and water leave the bloodstream
Air passes in and out of the lungs via the trachea (windpipe),
The diagram shows tiny air sacs called alveoli.
Each alveolus is surrounded by tiny blood vessels called capillaries.
Gaseous exchange takes place here.
Oxygen passes from the alveoli into the blood which is flowing through the
capillaries,
Carbon dioxide and water pass in the opposite direction; from the bloodstream
back into the alveoli where they are exhaled back out of the body.
The effect of smoking
Smoking has many adverse health effects, including cancer, heart disease,
pneumonia and bronchitis.
It clogs up the hairs in the nose, which reduces their effectiveness to filter incoming dust particles.
It also clogs up the alveoli in the lungs, reducing the ability to exchange gases.
Breathing happens when animals take in oxygen and give out carbon dioxide and water
10
Exam Questions
1. [2008 OL][2007][2012 OL]
Complete the following word equation for aerobic respiration.
Glucose (Food) + ____________ → Energy + _______________ + Water
2. [2007]
State how you would show the presence of the products of aerobic respiration by means of a chemical test.
3. [2007 OL]
Limewater was placed in test tube A and in test tube B.
(i) What effect has carbon dioxide on limewater?
The student inhaled through test tube A and exhaled
through test tube B twenty times.
The student saw no change in the appearance of the
limewater in test tube A. The appearance of the
limewater in test tube B had changed.
(ii) What change would you expect the student to have seen
in the limewater in test tube B?
(iii) What conclusion should the student have drawn from
what he/she saw?
4. [2006]
The diagram is of an apparatus used to show that exhaled air contains carbon dioxide.
When performing this experiment a control is required to show that inhaled air contains less
carbon dioxide than exhaled air.
Describe, using a labelled diagram, a suitable control procedure.
5. [2009]
The diagram shows the apparatus used by a pupil when performing an experiment in a school laboratory.
The pupil blew (exhaled) air into test tube X.
The pupil sucked (inhaled) air from test tube Y.
The pupil continued, alternately, blowing and sucking air, as
above, until liquid A in one of the test tubes turned milky.
(i) Name liquid A.
(ii) In which test tube, X or Y, did the liquid turn milky?
(iii) Why did liquid A turn milky in one of the test tubes?
(iv) What conclusion can be made from the result of this experiment
regarding the difference in composition between exhaled and
inhaled air?
(v) Complete the word equation, below, for aerobic respiration.
Food + ___________ → _____________________ + energy + water
6. [2010] [2006]
The diagram shows the internal structure of a human lung. There are about 350
million alveoli per lung.
Describe clearly the exchange of gases that occur between the air in the alveoli
and the bloodstream.
11
7. [2006 OL]
The heart pumps blood to the lungs and around the body.
The diagram shows part of the breathing system.
(i) Name the parts of the breathing system labelled X and Y in the diagram.
(ii) Complete the sentence below..
There is more ____________________ in exhaled air than in inhaled air.
(iii) A balance of exercise and rest promotes good health.
Name one activity which has a harmful effect on the breathing system.
8. [2010 OL]
The diagram shows part of the human breathing system.
(i) Name the parts labelled A and B in the diagram.
(ii) Part A has rings of cartilage.
What do the rings of cartilage do?
(iii)In which part of the breathing system does the gas exchange take place?
(iv) Why does exhaled air turn limewater milky?
9. [2009 OL]
The diagram shows a model of the human breathing system.
(i) Name the part of the breathing system represented by the balloons.
(ii) Choose from the list on the right the correct word to complete the sentence below.
The part of the breathing system represented by the bell-jar is the ___________.
Other Test Questions
1. Define the term respiration.
2. Give the word equation for respiration.
3. When a student exhales into a test-tube surrounded by a freezing mixture of ice and salt a colourless is formed
(i) What is this liquid and describe a test to prove it.
(ii) Why is necessary to put the test-tube in a freezing mixture?
4. How would you demonstrate that carbon dioxide is produced during respiration?
5. How would you demonstrate that heat energy is produced during respiration?
6. What is anaerobic respiration?
7. Draw a labelled diagram of the lungs – include trachea, bronchi, bronchioles and alveoli.
8. Give two effects of smoking on the breathing system.
12
Biology: 9. The Circulation System
Please remember to photocopy 4 pages onto one sheet by going A3→A4 and using back to back on the
photocopier
Syllabus
OB13 Describe the function and composition of blood (white blood cells, red blood cells and platelets in a
liquid called plasma) and state the function of each component .
OB14 State the function of the heart; describe its structure, identifying the four chambers; explain the
difference between the left and the right ventricle
OB15 Describe the passage of blood through the heart and lungs via arteries and veins, identify the
pulmonary artery and vein, aorta and vena cava, and distinguish between arteries, veins and
capillaries
OB16 Demonstrate the effect of exercise and rest on pulse and breathing rate and appreciate that a balance
of each promotes good health
OB17 Recall that the average pulse rate for an adult at rest is 70 b.p.m., and explain why exercise results in
increased pulse and breathing rates
OB18 Recall that the normal temperature of the human body is 37 °C, and that illness may cause a change
in body temperature
OB19 Associate the circulation of the products of digestion around the body with their absorbtion into the
bloodstream
Student Notes
Blood: composition and function of blood
Oxygen and food are absorbed into the bloodstream and are circulated around the body, to be
distributed to each cell in the body as required.
Part Function
Plasma Liquid part of blood.
Carries blood cells, digested food and wastes around the body
Red blood cells Contains haemoglobin (iron-based pigment) which carries the
oxygen
(5 million per mm3)
White blood
cells
Fight infection – engulf germs or release antibodies which kill
germs.
Platelets Blood clotting
The circulatory system consists of blood, the heart and blood vessels
13
The Heart The heart pumps blood around the body
There are four chambers in the heart
The four chambers of the heart consist of the right atrium, the left atrium the right ventricle, and the left
ventricle.
The 'DOUBLE' pump of the Human Heart
Passage of blood through the heart and lungs via arteries and veins (Syllabus: identify the pulmonary artery, pulmonary vein, aorta and vena cava)
Body → vena cava → right atrium → valves → right ventricle → pulmonary artery → lungs →
pulmonary vein → left atrium → left ventricle → aorta → body
1. Deoxygenated blood FROM THE BODY
entering the heart (via the VENA CAVA).
2. The RIGHT ATRIUM .
3. The VALVES prevent blood flowing the wrong
way when the atria and ventricles contract.
4. The RIGHT VENTRICLE.
5. Deoxygenated blood leaving the heart and
flowing TO THE LUNGS (via the
PULMONARY ARTERY).
6. Oxygenated blood FROM THE LUNGS
entering the heart (via the PULMONARY
VEIN).
7. The LEFT ATRIUM.
8. The thicker walled LEFT VENTRICLE.
9. Oxygenated blood leaving the heart and
flowing TO THE BODY (via the AORTA).
Remember:
1. For both the left and right-hand sides the blood flows through the heart in the following order:
Vein → Atrium → Ventricle → Artery i.e. V A V A (voom!)
2. Arteries carry blood Away from the heart. (Remember AA).
The difference between the left and right ventricles
The left ventricle has thicker walls than the right ventricle because the left ventricle pumps blood all around
the body whereas the right ventricle just pumps blood to the lungs.
14
The four main blood vessels going into and out of the heart
Blood vessels: Arteries, veins and capillaries
Blood vessel Carries blood
from:
Carries blood
to:
Pulmonary
artery
Heart Lungs
Pulmonary vein
Lungs Heart
Aorta
Heart Body
Vena cava
Body Heart
Arteries Veins Capillaries
Have thick walls to resist
pressure
Have thin wall because the pressure is
much less.
Have very thin walls one cell
thick) to allow substance to
pass in and out from cells.
Carry blood under high
pressure
Carry blood under low pressure
Cary blood AWAY from
heart
Carry blood TO the heart Connect arteries to veins
No valves
Have valves to prevent backflow of
blood
Narrow lumen
Wide lumen
Blood travels in spurts
Blood flows evenly
15
Your pulse
Why?
The body uses a lot of energy when exercising so the heart needs to pump a lot of oxygen and food around
the body. This results in an increase in heart-beat and rate of breathing.
To demonstrate the effect of exercise and rest on pulse and breathing rate
A pulse is caused by the surge of blood in an artery due to a heartbeat.
1. Count the number of beats per min at your wrist or at your neck.
2. Exercise vigorously for two minutes.
3. Take your pulse again.
Result: Your pulse rate should now be much greater.
Conclusion: Exercise increase heartbeat and pulse rate.
Exercise is beneficial to the heart as it makes it stronger and reduces weight.
Note: Heart rate can also be increased by excitement, anxiety and smoking.
A balance of exercise and rest promotes good health
The average pulse rate for an adult at rest is 70 beats per minute
Exercise results in increased pulse and breathing rates
The normal temperature of the human body is 37 °C but illness may cause a change in body temperature
16
Exam Questions
Blood
1. [2006] [2008] [2010 OL] [2006 OL][2012 OL]
Blood is a liquid tissue. Name any three components of blood.
Give the function of each of the components of blood you have named.
2. [2012]
(i) Why is blood considered to be a tissue?
(ii) Name a substance transported by blood.
The Heart
3. [2009 OL][2007 OL][2006][2012 OL]
Why is the wall of the left side of the heart thicker than the wall of the right
side?
4. [2009 OL]
The heart forms part of the circulatory system.
Answer the following questions on the heart and the circulatory system.
(i) The blood vessels labelled A in the diagram carry blood away from the heart.
Name this type of blood vessel.
(ii) What is the name of the small chamber of the heart labelled B in the diagram?
5. [2006 OL]
Name the chambers of the heart labelled X and Y in the diagram.
6. [2007 OL]
Blood moves through vessels called arteries and veins.
(i) What is the name of the blood vessels that carry blood away from the heart?
(ii) What is the name of the blood vessels that carry blood to the heart?
7. [2009]
Label clearly the pulmonary artery with an A, and the pulmonary vein with a V in
the diagram of the heart.
8. [2008]
The diagram shows cross sections of an artery and of a vein. Why do
arteries have much thicker walls than veins?
9. [2008]
Give one other structural difference between arteries and veins.
10. [2011]
The simplified diagram shows the flow of blood through the lungs, heart and
rest of the body.
(i) Name the blood vessels labeled A and B.
(ii) Capillaries are small blood vessels.
Describe the two changes in the composition of blood after it has passed
through the capillaries of the lungs shown.
(iii)What feature of capillaries allows these changes to happen?
(iv) Name the chamber of the heart that pumps blood to the lungs.
17
Your Pulse
11. [2006]
What causes a person’s pulse?
12. [2006]
The diagram shows a person’s pulse rate being taken.
How is a person’s pulse rate measured using this method?
13. [2010 OL][2012 OL]
A person’s pulse is often taken to measure the rate of heart beat.
Normal pulse rate is 70 beats per minute (bpm).
Exercise and rest have an effect on pulse rates.
Answer the following questions about exercise and healthy living.
(i) Exercise causes a person’s pulse rate to ________________________.
(ii) Rest causes a person’s pulse rate to ___________________________.
(iii)A balance of exercise and rest promotes good health.
Name one other action a person can take to keep their heart healthy.
14. [2006]
An athlete’s resting pulse rate is 58. After 10 minutes strenuous exercise their pulse rate was 120. After
resting for 5 minutes their pulse rate reduced to 63. Clearly account for the rise and fall in pulse rate
experienced by the athlete.
Other Test Questions
1. What is the main function of the heart?
2. What are the four main chambers of the heart?
3. Draw a diagram of the heart. Identify on the diagram the pulmonary artery and vein, aorta and vena
cava, and also the four main chambers.
4. Distinguish between arteries, veins and capillaries.
5. Describe how you would demonstrate the effect of exercise and rest on pulse and breathing rate.
6. What is the average pulse rate for an adult at rest?
7. What is the normal temperature of the human body?
8. What is the effect of illness on body temperature?
9. What is the average resting pulse?
10. What is the effect of exercise on your pulse?
11. Why do athletes train at high altitude, thereby increasing the number of red blood cells, to improve their
performance?
12. Does a fitter person’s heat rate return to normal quicker or slower?
18
Extra Material
The functions of the Circulatory System
1. To carry OXYGEN to all the cells in the body
2. To carry FOOD to all the cells in the body
3. To remove WASTE from the cells of the body
4. To distribute HEAT around the body
5. To form a part of the DEFENCE the body has against microbes
6. To REPAIR itself and prevent blood loss by clotting
[2012 OL]
In Ireland today heart disease is a major problem.
State one way in which heart disease can be prevented.
19
Physics: 12. Static Electricity Please remember to photocopy 4 pages onto one sheet by going A3→A4 and using back to back on the photocopier
Questions to make you think
1. Why do you sometimes get goose-pimples in cold weather?
2. Why does your hair stand up when you get a fright?
3. What do you think is the evolutionary purpose behind this (hint: it also happens when you get an
electrical shock)?
Syllabus
OP48 Use simple materials to generate static electricity; demonstrate the force between charged objects
and the effects of earthing.
Student Notes
When one object is rubbed against another, charges (electrons) often get transferred
from one object to the other.
Remember that electrons have a negative charge.
An object becomes positively charged if it loses electrons, and negatively charged if
it gains electrons.
Demonstration: using simple materials to generate static electricity
Option 1: Rub a biro (a balloon is even better) with a cloth to charge it and then use it to attract
pieces of tissue paper.
Option 2: A charged balloon can attract an empty coke can which is lying on a table.
Conclusion: Neutral objects are attracted to charged objects
To demonstrate the force between charged objects
1. Charge a plastic rod by rubbing it with a cloth and then hang it from a retort
stand.
2. Rub another rod with the same cloth (so that it will have the same charge) and
bring it up to the first rod.
Result:
The first rod will be repelled by the second rod.
Conclusion:
Similar charges repel.
Now bring up a different type of charged rod (which has an opposite charge).
Result:
The first rod will move towards the second rod.
Conclusion
Opposite charges attract.
A conductor is a substance that allows charge to flow through it easily (metals are conductors)
An insulator is a substance that does not allow charge to flow through it (plastics are insulators)
Similar charges repel; opposite charges attract
20
Earthing
Earthing means connecting a charged object to the earth by means of a conductor, so that most of the charge
which was on the object flows to the earth.
If a rod is charged then all the charges on the rod are repelled from each other and will try to escape from the
material if they can. If the material is an insulator like plastic then the charges are not able to move and so
remain on the material.
However if you touch the material with your fingers then the points of contact become ‘earthed’ because the
charges get transferred to earth via your body. When an object loses charge in this manner we say it gets
‘earthed’.
Similarly the charges can transfer into the air if there is a lot of moisture in the air because water is a
conductor.
Useful effects of static electricity
1. Removing soot from chimneys
2. Spray-painting
Nuisance effects of static electricity
1. Television screens attracting dust
2. Lightning
21
Exam Questions
1. [2006 OL]
A student set up the circuit drawn on the right to investigate different
materials to see which were electrical conductors and which were
electrical insulators.
(i) What would you expect to observe when an electrical conductor is
connected between the contact points A and B? Give a reason for your
answer.
(ii) What would you expect to observe when an electrical insulator is
connected between the contact points A and B? Give a reason for your
answer.
2. [2008]
Two rods A and B, made from different plastics, were given the static
electrical charges shown in the diagram.
How could you have charged the rods as shown?
3. [2008]
Describe with the help of a labelled diagram how the force between the
two charged rods A and B could be investigated.
What result would you expect from this investigation?
4. [2011 OL]
The diagram shows a freely suspended charged rod.
(i) What happens when a similarly charged rod is brought close to the suspended rod?
(ii) What does this tell us about like charges?
5. [2008]
In dry weather you can sometimes get an electric shock from a supermarket trolley.
This is caused by the build-up of static electricity on the trolley.
Explain clearly why this only happens in dry weather.
6. [2009][2012]
A plastic pen when rubbed with a dry cloth can attract small pieces of paper which
‘stick’ to it.
(i) Why does this happen?
(ii) Explain why the pieces of paper fall from the pen after some time.
7. [2011]
The boy in the photo is touching a charged globe that is at high voltage.
He is insulated from the earth.
What property of electric charge causes the boy’s hair to stand on end and
apart?
8. [2006 OL]
(i) What type of energy generates lightning?
(ii) The flash of lightning is seen before the thunder is heard.
What does this tell us about the speed of light?
Other Test Questions
1. What is the difference between a conductor and an insulator?
2. Write out the following sentence, filling in the missing words:
Similarly-charged objects ______________ while oppositely-charged objects ______________.
22
3. Describe briefly how you would investigate the relationship between two similarly charged objects.
4. Give one example of when static electricity is useful and one example of when static electricity can be a
nuisance (apart from getting a shock)?
5. When a Perspex rod is rubbed with a cloth it becomes positively charged. Explain in terms of electron
transfer how this occurs.
23
Physics: 13. Current Electricity
Questions to think about
1. Given a battery, lightbulb and wires could you put the circuit together to make the lightbulb light up?
Syllabus
OP49 Test electrical conduction in a variety of materials, and classify each material as a conductor or insulator
OP50 Set up a simple electric circuit, use appropriate instruments to measure current, potential difference (voltage)
and resistance, and establish the relationship between them
OP51 Demonstrate simple series and parallel circuits containing a switch and two bulbs
OP52 Perform simple calculations based on the relationship between current, potential difference (voltage), and
resistance
Student Notes
Conductors and Insulators
Remember our definitions of conductors and insulators from the chapter on Static Electricity:
A conductor is a substance that allows charge to flow through it easily (metals are conductors).
An insulator is a substance that does not allow charge to flow through it (plastics are insulators).
Experiment: Identify materials as conductors or insulators
1. Set up the circuit as shown.
2. Place various
different
materials between
points X and Y in
the circuit and
turn on the switch.
3. If the bulb lights then the material is a conductor and if it doesn’t then the material is an insulator.
Label Circuit component
A Switch
B Power supply
C Resistor
D Bulb
24
Resistors
A resistor is used to reduce the flow of current in a circuit.
A series circuit
This is where the two bulbs are connected one after the other.
All the current coming from the battery goes through both bulbs.
Advantage: Uses less electricity than if the bulbs are connected in parallel.
Disadvantage: If one bulb blows the circuit is broken and so no current flows,
e.g. lights in a Christmas tree.
A parallel circuit
The current coming from the battery splits up and some goes through each
bulb.
Advantage: If one bulb blows there will still be a complete circuit through the
other bulb so it will remain lit.
Light bulbs in a house are generally connected in parallel for this reason.
Disadvantage: It uses more electricity than if connected in series.
25
Current, voltage and resistance
1. Current
The unit of current is the amp (the symbol for the amp is A).
The symbol for current is I.
Current is measured with an ammeter or multimeter.
For current to flow we need two things:
1. There has to be a complete circuit.
2. There has to be a source of potential difference (power supplies and batteries both act as a source of potential
difference).
2. Potential difference (commonly called ‘voltage’)
Current will flow between two points if there is a potential difference between the two points.
This is a bit like saying that water will flow between two points if there is a height difference between the two points.
Another way of thinking about potential difference is that it provides the ‘push’ to move the electrons around a circuit.
The unit of potential difference is the volt (the symbol for the volt is V)
The symbol for potential difference is V.
Potential difference is measured with a voltmeter or multimeter.
3. Resistance
The unit of resistance is the ohm (the symbol for the ohm is Ω).
The symbol for resistance is R.
Resistance is measured with an ohmmeter or mulitmeter.
Summary
Quantity Symbol Unit Symbol Measured with Symbol
Current I Amps A Ammeter
Potential
difference
V Volts V Voltmeter
Resistance R Ohms Ω Ohmmeter
Relationship between current, potential difference and resistance
Maths problems
Calculate the resistance of a resistor when 20 V produces a current of 4 A.
Answer
V = 20 Volts
I = 4 Amps
R = V÷I = 20 ÷ 4 = 5 Ohms
Current is a flow of charge (the charge is usually electrons)
V = RI
Resistance opposes the movement of electrons around a circuit
In an electric circuit, current flows from the positive end of the battery to the negative end.
The positive end is represented with a long solid line, and the negative end is represented with a short solid line
26
Fill in the following table using the formula V = IR:
Experiment: To establish the relationship between potential difference and current
1. Set up the circuit as shown and note the current (I) and potential difference (V)
2. Adjust the variable resistor (rheostat) to get a new set of values.
3. Repeat about 6 times and then plot a graph of potential difference against current.
4. The fact that we get a straight line shows that the potential difference is proportional to the current (this means that
if we double the potential difference, the current will double also).
5. Note that the slope of the graph corresponds to the resistance of the component.
This is what the graph should look like
Potential Difference (V) Current (I) Resistance
(R)
10 5
2 200
120 30
100 2
0.5 20
120 10
27
Exam questions
1. [2008 OL]
The diagram shows a simple electrical circuit.
Complete the table below correctly matching each of the names of the components in the
circuit with one of the labels A, B, C or D.
2. [2008 OL][2012 OL]
You are given a piece of copper metal and a piece of timber.
Which piece, metal or wood, should you connect between X and Y in order that the bulb
would light when the switch is closed? Give a reason for your choice.
3. [2007 OL]
A student set up the circuit shown to investigate the relationship
between the potential difference (voltage), the current and the
resistance of a wire conductor.
Gaps are left in the diagram in the places where the ammeter and
voltmeter should be placed. The symbols for these devices are given on
the right.
Complete the circuit inserting the symbols for the ammeter and the voltmeter in their correct positions.
4. [2007]
The symbols for two electrical meters are given in the diagram.
The symbol is for a meter that measures potential difference, often called ‘voltage’.
What electrical quantity can be measured using the meter with the symbol ?
5. [2006][2011 OL]
Components, e.g. bulbs, in electrical circuits can be connected in series or in parallel.
It is noticed that, when one headlight fails (blows) in a car, the second remains lighting.
(i) State the way the headlights are connected and give a reason why this mode of connection is
used.
(ii) All of the bulbs go out in an old set of Christmas tree lights, when one of bulbs fails (blows).
In what way are the bulbs connected in this set of lights?
(iii) Explain why, when one bulb blows, they all go out.
6. [2006]
Calculate the resistance of the filament of a car headlamp when 12 V produces a current of 5 A in it.
In what unit is resistance measured?
Label Circuit component
Bulb
Power supply
Resistor
Switch
28
7. [2012 OL]
A student carried out an investigation of the relationship between current flowing through a wire resistor and the
voltage across it.
The data collected is presented in the table below.
The student then used this data to draw a graph of voltage (y-axis) against current (x-axis)
(i) Use the graph to estimate the current at 2.5 V.
(ii) Name the instrument used by the student to measure voltage.
(iii) What is the relationship between the current and the voltage in this investigation?
Current (A) 0 0.2 0.4 0.6 0.8 1.0
Voltage (V) 0 1 2 3 4 5
29
8. [2007 OL]
The student used the variable voltage supply to apply different voltages across the resistor.
She measured the voltage across the resistor and the current passing through it several times.
She collected the following data.
(i) Draw a graph of the voltage (y-axis) against the current (x-axis).
(ii) What conclusion can you draw from the graph about the relationship between the potential difference (voltage)
and the current passing through the wire conductor?
Voltage (V) 0 2 4 6 8
Current (A) 0 0.5 1.0 1.5 2.0
30
9. [2010 OL]
A student carried out an investigation of the relationship between current flowing through a wire resistor and the
voltage across it.
The data collected is presented in the table below.
(i) Use this data to draw a graph of voltage (y-axis) against current (x-axis) using the grid provided below.
(ii) Use the graph to estimate the current at 3.5 V.
(iii) Name the instrument used by students to measure voltage.
(iv) Name the instrument used by students to vary the current.
(v) What is the relationship between voltage and current in this investigation?
10. [2007]
Meters and are used in the circuit shown.
Enter ‘A’ into the appropriate circle of one of the meter symbols in the circuit
diagram so as to clearly identify its correct position.
11. [2007]
A pupil used the circuit above to get a set of
readings from both meters for different values
and then plotted this data in the graph shown.
Use this graph to calculate the resistance of
resistor R shown in the diagram. Give the unit of
resistance with your answer.
Current (A) 0.2 0.4 0.6 0.8 1.0
Voltage (V) 1 2 3 4 5
31
Other Test Questions 1. Why is electricity a convenient form of energy?
2. What is an electric current?
3. What is the unit of current?
4. What is the unit of voltage (also called the potential difference)?
5. What is the unit of resistance?
6. Name an instrument used to measure electric current.
7. Name an instrument used to measure voltage.
8. Name an instrument used to measure resistance.
9. What two conditions are required in order for current to flow in a circuit?
10. Draw the symbol for each of the following underneath the word
Resistor Switch Voltmeter Light Bulb Battery Rheostat
11. What is meant by the term ‘Potential Difference’ (or ‘Voltage’) as it applies to a circuit?
12. (i) You are given a battery and two light-bulbs.
(ii) Draw a circuit diagram showing the batteries arranged (i) in parallel, (ii) in series.
(iii) Which circuit will be brighter?
(iv) In which circuit will the battery last longer?
(v) Which circuit is more likely to represent the arrangement of Christmas lights? Why?
13. A battery provides a potential difference of 9 volts across a metallic conductor of resistance 0.5 ohms. Calculate
the current flowing through the circuit.
14. Draw a fully labelled diagram of the apparatus used in the experiment to establish the relationship between
potential difference and current.
15. Sketch the graph which you would expect to obtain from this experiment.
What does the slope of the graph represent?
16. The measurements made by a student in an experiment to establish the relationship between potential difference
and current are shown in the table.
Voltage (V) 1.0 2.0 3.0 4.0 5.0 6.0
Current (A) 0.1 0.2 0.3 0.4 0.5 0.6
(i) Use the table to draw a graph – on graph paper - of voltage against current.
Put voltage on the Y-axis.
(ii) What is the relationship between potential difference and current?
Give a reason for your answer.
(iii) Calculate the resistance of the resistor used in this experiment.
17. Draw the symbol for each of the following underneath the word
Resistor Switch Voltmeter Light Bulb Battery Rheostat
18. What is meant by the term ‘Potential Difference’ (or ‘Voltage’) as it applies to a circuit?
32
Chemistry: 13. Ionic and Covalent Bonding
Please remember to photocopy 4 pages onto one sheet by going A3→A4 and using back to back on the
photocopier
Syllabus
OC41 Understand how atoms of elements combine to form compounds
OC42 Recall that ionic bonding is an attraction between positive and negative ions; describe the bonding in
NaCl and MgO as examples
OC43 State what a molecule is, understand that covalent bonds involve the sharing of pairs of electrons,
and describe the bonding in H2, O2, H2O, CH4 as examples of covalent bonding
OC44 Investigate the ability of ionic and covalent substances to conduct electricity
Student Notes
Compounds and Molecules
Remember our definitions of molecules and compounds from chapter 2: Elements, Compounds and
Mixtures?
A molecule is made up of two or more atoms chemically combined.
A molecule is the smallest part of an element or compound that can exist on its own
Compounds are substances made from two or more different elements chemically combined.
So what does this phrase ‘chemically combined’ mean?
First we need to note that there are two ways for atoms to combine chemically, and that another word for the
process of combining chemically is ‘bonding’.
Bonding
There are two separate methods by which atoms join up:
1. Ionic bonding occurs when an atom loses or gains electrons
2. Covalent bonding occurs when an atom shares electrons.
Bonding occurs because all atoms try to have a full outer shell, and will lose, gain or share electrons in order to do so
33
Ionic bonding
If an atom loses an electron then it becomes a positive ion.
If an atom gains an electron then it becomes a negative ion.
In ionic bonding positive ions are attracted to negative ions.
An example of an ionic bond is sodium chloride
The bonds in sodium chloride are formed by sodium atoms losing electrons and chlorine atoms gaining
electrons.
Examples of ionic bonding: (i) Sodium Chloride (NaCl)
The atomic number of sodium is 11.
It has an electronic configuration of 2, 8, 1. This means that it needs to lose the one electron which it has in
its outer shell in order to have a complete outer shell.
The atomic number of chlorine is 17.
Chlorine has an electronic configuration of 2, 8, 7. This
means it needs to gain one electron in order to have a
complete outer shell.
When a sodium atom bonds with a chlorine atom the sodium
atom loses its outer electron to form a positive ion while the
chlorine atom gains an electron to form a negative ion.
The two atoms now have opposite charges and because
opposite charges attract both atoms move off together as a
sodium-chloride (NaCl) molecule.
Examples of ionic bonding: (ii) Magnesium Oxide
(MgO)
The atomic number of magnesium is 12.
It has an electronic configuration of 2, 8, 2. This means
that it needs to lose the two electrons which it has in its
outer shell in order to have a complete outer shell.
The atomic number of oxygen is 8.
Oxygen has an electronic configuration of 2, 6. This means
it needs to gain two electrons in order to have a complete
outer shell.
When a magnesium atom bonds with an oxygen atom the
sodium atom loses its two outer electrons to form a
positive ion while the oxygen atom gains two electrons to
form a negative ion.
The two atoms now have opposite charges and because
opposite charges attract both atoms move off together as a
magnesium-oxide (MgO) molecule.
An ion is a charged atom – i.e. an atom which has lost or gained electrons
An ionic bond is a bond formed by the force of attraction between two oppositely charged ions
34
Covalent bonding
Examples of covalent bonds are H2, O2, H2O and CH4 (methane) molecules.
The bonds in these molecules are formed by the atoms in the molecules sharing electrons with each other..
Examples of covalent bonding: (i) A hydrogen molecule (H2)
The atomic number of hydrogen is 1.
It needs to have two electrons in its outer shell, and so if it ‘bonds’ with
another hydrogen atom and they both ‘share’ their electron with each other, it
has the effect of allowing both atoms to have a complete outer shell.
Examples of covalent bonding: (ii) An oxygen molecule (O2)
The atomic number of oxygen is 8.
It has an electronic configuration of 2, 6.
It needs to have 8 electrons in its outer shell, and so if it ‘bonds’ with another
oxygen atom and they both ‘share’ two of their electrons with each other, it
has the effect of allowing both atoms to have a complete outer shell.
Examples of covalent bonding: (iii) A water molecule (H2O)
The atomic number of hydrogen is 1 so it has 1 electron in its outer shell.
The atomic number of oxygen is 8 so it has 6 electrons in its outer shell.
Oxygen can share 1 electron with one hydrogen atom and a second electron
with a second hydrogen atom, which has the effect of allowing all atoms to
have a complete outer shell.
Examples of covalent bonding: (iv) A methane molecule (CH4)
The atomic number of hydrogen is 1 so it has 1 electron in its outer shell.
The atomic number of carbon is 6 so it has 4 electrons in its outer shell.
Carbon can share 1 electron with each of 4 different hydrogen atoms, which
has the effect of allowing all atoms to have a complete outer shell.
A covalent bond is a bond formed by different atoms sharing electrons in order to have a complete outer shell
35
To investigate the ability of ionic and covalent substances to conduct electricity
Procedure
Set up a circuit as shown in the
diagram.
Select a number of different
substances for testing, e.g. table
salt, copper sulphate (both ionic
substances), cooking oil and sugar
(both covalent substances).
If the substances are solid then they
should be dissolved in pure water
before testing.
If the bulb glows then the
substance is a conductor and if it
doesn’t glow then it is an insulator.
Result
The bulb will only glow for ionic substances.
Conclusion
Only ionic substances conduct electricity.
Silly exam question:
Why were the solid substances dissolved in water before the investigation?
Answer:
To allow the particles to move
Properties of Ionic and Covalent compounds
Ionic Compounds Covalent Compounds
Usually solid at room temperature Usually liquid or gas at room temperature
High melting and boiling points Low melting points
Soluble in water Insoluble in water
Conducts electricity Do not conduct electricity
Undergo fast reactions Undergo slow reactions
36
Exam Questions
Ionic Bonding
1. [2007 OL][2012 OL]
Complete the sentence: In _________ bonding positive ions are attracted to negative ions.
2. [2006 OL]
The bonds in sodium chloride are formed by sodium atoms losing electrons and chlorine atoms gaining
electrons.
Name the type of bond found in a sodium-chloride crystal.
3. [2008][2012]
Atoms of different elements can form compounds by bonding together.
What is an ionic bond?
4. [2008]
A pupil investigated the ability of
covalent and ionic substances to conduct
electricity. Four substances were
selected. One was a liquid. The other
three substances were solids and these
were dissolved in pure water before
testing.
The apparatus used in the investigation
is drawn below. When the liquids were
tested the bulb did not glow in some
cases (Liquid type A) and the bulb
glowed in other cases (Liquid type B).
The results of the investigation are
given in the table.
(i) Name the ionic substances in the table. Give a reason for your answer.
(ii) Three of the substances tested are solid at room temperature. Why were these substances dissolved in
water before the investigation?
5. [2009]
The diagram shows sodium ions (+) and chloride ions (-) in part of a
crystal of table salt, sodium chloride.
(i) How are sodium ions and chloride ions formed from their atoms?
(ii) What force holds the ions together in sodium chloride?
(iii)Name one other compound that is composed of ions.
Liquid Cooking oil Table
salt
Table
sugar
Copper
sulphate
Liquid
type
A B A B
37
Covalent Bonding
6. [20ll OL]2007 OL][2012 OL]
Complete the sentence: In _________ bonding pairs of electrons are shared.
7. [2007]
The diagram shows a molecule of C60. It has 60 carbon atoms covalently bonded
together.
This molecule is nick-named the ‘Buckey Ball’.
Explain the underlined term.
8. [2006 OL]
The bond in a molecule of hydrogen gas is formed by a shared pair of electrons.
Name the type of bond found in hydrogen gas.
9. [2008]
Some atoms join together by sharing pairs of electrons.
This is called covalent bonding.
Draw a diagram showing the covalent bonding in a molecule of water.
10. [2011]
The diagram shows the way the atoms bond together in a molecule of water.
(i) Each hydrogen atom shares two electrons with the oxygen atom.
What name is given to the type of bonding that involves the sharing of pairs
of electrons?
(ii) Draw a diagram of a methane molecule, CH4, showing the bonding between
its atoms.
(iii)Describe a second type of chemical bonding and name a compound which
has this type of bonding.
11. [2009]
The diagram shows a group of water molecules with one enlarged below
with its constituent atoms identified by their atomic symbols.
Water molecules are very tiny, one teaspoon of water contains
approximately 2 × 1023
molecules.
(i) Name the type of bonding in the water molecule.
(ii) Describe this type of bond.
(iii)Name one other compound with this type of bonding.
38
Other Test Questions
1. Name one property of ionic and one property of covalent compounds:
2. Draw a diagram (using suitable circuit symbols) of the circuit needed to investigate the ability of ionic
and covalent compounds to conduct electricity.
3. How could you tell whether a compound was ionic or covalent?
4. Draw a diagram showing the ionic bonding in the compound magnesium oxide.
5. Draw a diagram showing the bonding in a water molecule.
6. Draw a labelled diagram to show the type of bonding in an oxygen molecule.
7. Name the type of bonding present in a crystal of sodium chloride.
Give one property of this type of bonding:
8. In a negatively charged ion the number of is greater than the number of
.
9. In a positively charged ion the number of is greater than the number of
.
10. List two properties of an ionic substance.
11. List two properties of compounds which are formed by sharing electrons.
12. Underline the two elements in the list below that normally exist as molecules:
Hydrogen Chlorine Helium Aluminium Gold.
