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GCSE TWENTY FIRST CENTURY SCIENCE
ADDITIONAL SCIENCE A
A218/02 Unit 4: Ideas in Context (Higher Tier)
RESOURCE BOOKLET
JUNE 2012
* A 2 1 4 0 0 0 6 1 2 *
INSTRUCTIONS TO CANDIDATES
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This booklet contains three articles.
Take these articles away and read them through carefully.
Spend some time looking up any technical terms or phrases you do not understand.
For the examination on Wednesday 30 May 2012 you will be given a fresh copy of these
articles, together with a question paper.
You will not be able to take your original copy into the examination with you.
INFORMATION FOR CANDIDATES
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This document consists of 8 pages. Any blank pages are indicated.
© OCR 2012 [K/103/3777]
DC (SHW (SW) 00664 3/11) 47591/2
OCR is an exempt Charity
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2
Hypothermia – a hazard for mountaineers
Any climb or walk that exposes people to extremely cold conditions can put them at risk of suffering
from hypothermia. Mountaineers are particularly at risk.
Hypothermia is a condition where the core body temperature drops below that required for normal
reactions and body functions.
Core body temperature is usually maintained within the normal range of 36.5–37.5 °C by a process
called temperature regulation. This is a form of homeostasis, using special receptors and effectors in
the nervous system and involving negative feedback.
If a person is exposed to cold external conditions and if their internal mechanisms are unable to
balance heat loss with heat gain, a drop in core body temperature occurs. As the core body temperature
decreases, characteristic symptoms occur, such as shivering and mental confusion.
© OCR 2012
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Signs and symptoms
The signs and symptoms vary depending on the degree of hypothermia. There are three main stages
of this condition: mild, moderate and severe. The table shows one way of classifying the stages of
hypothermia.
Table showing the classification of hypothermia
hypothermia stages
core body temperature in °C
mild
moderate
severe
35–32
32–28
below 28
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Symptoms of mild hypothermia include shivering and some mental confusion.
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During moderate hypothermia, shivering becomes more violent. The person may stumble over
objects and have mild confusion. The lips, ears, fingers and toes can also appear pale.
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A person with severe hypothermia finds it difficult to speak and can lose the use of their hands.
Stumbling often occurs. Under extreme conditions, the person may find walking impossible and
the pulse and breathing rates decrease significantly.
Advice to reduce the risk of getting hypothermia when climbing mountains
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Eat properly, with plenty of carbohydrates and fats.
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Drink plenty of water.
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Get enough sleep. Climbing mountains is hard work.
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Change out of wet clothes as soon as possible.
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Wear warm clothing, particularly around the head and neck.
© OCR 2012
A218/02/RB Jun12
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4
The dangers and delights of chlorine and bromine
Chlorine and bromine are elements from the halogens (group 7 of the Periodic Table). They are both
much more important to our everyday lives than many people realise.
chlorine atom
seven
electrons in
the outer shell
Cl
three
electron
shells
Like any family, all the halogens are similar to each other, but like any family there are differences
between them too. For example, each element has a similar outer shell electron arrangement but their
physical properties change down the group.
Physical properties
melting point in °C
boiling point in °C
density in g / cm3
chlorine
–101
–34
0.003
bromine
–7
59
element
© OCR 2012
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Chlorine
Chlorine is the second element in group 7 (below fluorine in the Periodic Table). Chlorine is a very toxic
gas. It is more toxic than all the other elements in group 7, apart from fluorine. It is so hazardous to
handle that it is usually made right next to the factories that use it.
Chlorine is very hazardous to transport by road. If there is a large spillage, it spreads quickly over a
very wide area. Even small concentrations can cause serious health problems.
concentration of chlorine
in air in parts per million
0.2
effect on people
noticeable smell
30
coughing and vomiting
60
lung damage
1000
death
Chlorine is made by passing an electric current through a solution of sodium chloride in water. This is
just salty water. The solution conducts electricity because sodium chloride is an ionic compound. Other
useful products are made in the same reaction, so it is a very useful process.
Bromine
Bromine is the third element in group 7. Bromine can also be made from sea water – this time it is
the bromide salts that are important. No electricity is used – chlorine is used instead. When chlorine
bubbles through a solution of a bromide compound, the element bromine is made.
sodium bromide + chlorine
sodium chloride + bromine
This works with any halogen compound, as long as the halogen is less reactive than chlorine.
Bromine is nasty stuff. It is toxic and corrosive. It can be transported by road in special tankers lined
with lead.
Chlorine is used to treat drinking water. All of our sofas and chairs are treated with flame retardants
made using bromine (flame retardants make fabrics less flammable).
It is amazing to think that both of these elements come from sea water.
© OCR 2012
A218/02/RB Jun12
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6
The National Grid
The National Grid is the high-voltage electric
power transmission grid in the UK. It ensures
that electricity generated anywhere in the UK
can be used anywhere else in the country.
Generators used in power stations produce
electricity at about 23 kV. Transformers increase
this voltage for transmission through the Grid.
The National Grid delivers electricity to major
substations. Transformers then reduce the
voltage for the electricity supply to factories and
homes.
History
This table shows the history of the National Grid.
End of
19th century
Nikola Tesla establishes the principles of alternating current high-voltage electrical
power distribution while working for Westinghouse in the United States.
1901
Charles Merz opens the first major UK power station (the Neptune Bank power
station near Newcastle upon Tyne).
1912
The integrated power system developed by Merz in the north east of England is
the largest in Europe. It uses an alternating current system. The rest of the UK,
however, continues to use a patchwork of small supply networks.
1925
The UK government asks William Douglas Weir, a Glasgow industrialist, to solve the
problem of Britain’s inefficient electricity supply industry. Weir consults Merz, and
the result is the formation of the Central Electricity Board.
1933
The Central Electricity Board sets up the UK’s first nationwide a.c. grid, running at
132 kV, 50 Hz.
1949
The Grid is upgraded when links at 275 kV are added.
1965
The Grid is further upgraded by adding some 400 kV links.
© OCR 2012
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Facts from the 2005/6 National Grid Report
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Maximum demand: 63 Gigawatts
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Annual electrical energy used in the UK : 360 TWh (1.3 EJ)
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Capacity: 80 GW
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Number of large power stations: 181
Power Losses in the Grid
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Generator transformer heating losses: 0.157 GW
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In cables: 0.858 GW
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Substation transformer heating losses: 0.142 GW
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Other losses: 0.266 GW
Planning for the future
On average, approximately 11 GW produced in the north of the UK (particularly Scotland and northern
England) is transferred through the National Grid to be used in the south of the UK. This is expected to
grow to approximately 12 GW by 2014. It has been suggested that any new power stations should be
built in the south.
© OCR 2012
A218/02/RB Jun12
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© OCR 2012
A218/02/RB Jun12
Article 1- Homeostasis and Hypothermia questions
1.
What is hypothermia?
2.
What is the normal range for core body temperature?
3.
Explain what is meant by core body temperature.
4.
What is meant by the term temperature regulation (thermoregulation)?
5.
Why is temperature regulation important in humans?
6.
What part of the body controls temperature regulation?
7.
What are processes through which the body can lose heat?
8.
What are receptors?
9.
What are effectors?
10. What is negative feedback?
11. Draw a diagram to show how negative feedback maintains core body temperature.
12. What is a control centre?
13. In full sentences, explain how negative feedback maintains core body temperature.
14. Why is temperature important for enzyme function?
15. What is vasoconstriction?
16. What is vasodilatation?
17. Describe the processes that lead up to vasoconstriction.
18. During moderate hypothermia lips, ears, fingers and toes can appear pale. Explain why.
19. What is the function of shivering?
20. Suggest how a person with mild hypothermia should be treated. Give reasons for each suggestion.
21. Suggest how a person with moderate hypothermia should be treated. Give reasons for each suggestion.
22. Suggest how a person with severe hypothermia should be treated. Give reasons for each suggestion.
23. Explain how alcohol impairs temperature regulation.
24. Explain why people with hypothermia should not be given alcoholic drinks.
25. Why is it important that warm clothing should be worn around the head and neck?
26. What are carbohydrates?
27. In terms of their ability to release energy, why are carbohydrates recommended for persons with hypothermia?
28. In terms of their ability to release energy, why are fats recommended for persons with hypothermia?
29. Why does the pulse and breathing rate decrease significantly in a person with severe hypothermia?
30. What effect do wet clothes have on a person’s ability to maintain their core body temperature?
31. Why is the removal of wet clothes recommended for persons with hypothermia?
32. Suggest reasons why shivering stops during severe hypothermia.
Unit 4: Ideas in Context [Additional]
May 30th exam
Article 2 - The dangers and delights of chlorine and bromine Practice
Questions
1.
2.
3.
4.
5.
6.
7.
What are the chemical formulas for each of the halogen molecules?
Explain why the halogens are described as being diatomic atoms?
Write the electron configurations for fluorine, chlorine, and bromine.
Write the electron configurations for the fluoride, chloride, ad bromide ions.
Write the symbols of the fluoride, chloride, ad bromide ions.
Name the similarities and differences between each of the halogens.
State the trends of the halogens, in terms, of the colour of compound, state at room
temperature, reactivity, and boiling and melting point.
8. Why is chlorine a gas at room temperature, use the table on page 4 of the article to help?
9. Draw the hazard symbols for: toxic, corrosive, harmful, and irritant.
10. Why is fluorine more toxic than chlorine?
11. Why would chlorine cause health problems, explain the mechanism of how it would
cause these problems.
12. Explain why if chlorine is a hazard it is safe to use swimming pools.
13. What is the process used to separate chlorine from sea water?
14. Draw and annotate this process.
15. During this process, why does the chlorine compound have to be in solution form?
16. What does an ionic compound mean?
17. Write down the formula for sodium chloride and magnesium chloride and explain why
they are different.
18. Write down the equation for the reaction of sodium and chlorine, with symbols and state
symbols.
19. What does electrostatic attraction mean and how does this relate to question 18.
20. List some uses of chlorine and bromine.
21. Explain what is meant by the term displacement.
22. Why is bromine separated through the process of displacement, what are some
advantages of this process.
23. Write the symbol equation of sodium bromine and fluorine.
24. What is the state of a substance when it is dissolved in water?
25. What are the hazards with chlorine and bromine?
Article 3 - The National Grid
1.
What is the function of a transformer?
(1)
2.
a.
b.
3.
What is the name of a transformer that increases voltage?
What is the name of a transformer that decreases voltage?
Choose the correct phrase:
Electricity is transmitted as alternating current / direct current in the National Grid.
(1)
(1)
4.
Explain why electrical power is transmitted at very high voltage.
5.
Describe how alternating current is different from direct current.
6.
Explain what 50Hz means.
7.
Explain two advantages of having one, huge power network covering the whole
country instead of several small, local power grids.
(2)
Calculate the total power loss in the Grid for 2005/6.
(2)
8.
(2)
(1)
(1)
9.
a.
b.
What was the maximum demand for power in 2005/6?
Explain how you expect the maximum demand for power
in 2011/12 to compare with the value for 2005/6.
(1)
(2)
10. Suggest why people might not want a power station built near their homes.
(1)
11. Draw an energy transfer diagram for a transformer.
(3)
12. Write down the formula for transformers.
(1)
13. A transformer has 100 turns on the primary coil, 5000 turns on the secondary coil.
The primary voltage is 12kV.
a. Is this step-up or step-down?
(1)
b. Calculate the secondary voltage. (2)
c.
ANSWERS
1.
2.
A device that changes the size of an alternating voltage
a.
b.
Step up
Step down
3.
alternating current
4.
High voltage means current is low, less energy lost as heat in the wires/cables.
5.
Direct current goes one-way, alternating changes direction
6.
50 times per second
7.
Anything sensible e.g. power can be diverted from one area to another to meet demand,
less chance of power cuts if a power station breaks down.
8.
0.157 + 0.858 + 0.142 + 0.266 = ________ GW
9.
a.
b.
63GW
Greater because (any sensible reason e.g. more electrical gadgets, more people)
10. Anything relevant e.g. pollution
11. Electrical →electrical + sound + heat
12. Vp/Vs = Np/Ns
or equivalent (it is on the data sheet)
13. A transformer has 100 turns on the primary coil, 5000 turns on the secondary coil.
The primary voltage is 12kV.
a. Step up
b. Ns/Np = 5000/100 = 50
Vp x 50 = 600kV