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P2: Living for P2: Living for the Futurethe Future
Key points for revision Key points for revision (Foundation)(Foundation)
Energy from the SunEnergy from the SunThe Sun• is a stable source of energy• transfers energy to the Earth as light
and heat• is a renewable source of energy
Energy from the SunEnergy from the Sun
The Sun’s energy can be collected:• by photocells• by being absorbed by a surface and
transferred into heat energy• from convection currents that cause the
wind to blow and to transfer kinetic energy to electricity in a wind turbine
• by passive solar heating through glass• by a curved mirror that can focus the
rays
Advantages of photocellsAdvantages of photocells• low maintenance• no need for power cables• no need for fuel• long life• rugged• use renewable energy resource• no polluting waste
Disadvantages of photocellsDisadvantages of photocells• No power at night• No / low power in bad weather
Generating electricityGenerating electricity
• Batteries produce direct current (DC)• Generators produce alternating current
(DC)A generator can produce more electric
current:1. by using a stronger magnet2. more coils of wire3. moving the magnet or coils faster
Generating electricity in a Generating electricity in a power stationpower station
• Fuel is burned• producing steam• spinning a turbine• causing the turbine to turn the
generator
• A lot of energy is transferred to the environment in the form of heat
TransformersTransformers• Increase or decrease voltage• Electricity is transmitted at a high
voltage to reduce the amount of energy wasted
Fuels in power stationsFuels in power stations
• Fossil fuels: oil, coal, natural gas• Renewable biomass: wood, straw,
manure• Nuclear fuel
• All fuels release energy in the form of heat
EquationsEquations
• power = voltage x current• (watts) (volts) (amps)
• energy = power x time• (kilowatt-hours) (kilowatts)
(hours)
RadioactivityRadioactivity
• Ionising radiations from radioactive waste can cause cancer
• Uranium is a non-renewable fuel• Plutonium1. is a waste product from nuclear
reactors2. can be used to make nuclear bombs
Background RadiationBackground Radiation• Background radiation is around us
all of the time• Background radiation comes from:1. rocks & soil2. cosmic rays
Nuclear RadiationNuclear Radiation
• Alpha can travel a few cm in airis stopped by paper
• Beta can travel about a metre in airis stopped by a few mm of aluminium
• Gamma can travel a very long way in air is reduced by a few cm of lead
Radioactive SafetyRadioactive Safety
• Wear protective clothing• Use tongs; don’t touch sources• Keep sources at a sensible distance• Use radioactive materials for short
amounts of time• Label & store the sources carefully
Uses of radioactivityUses of radioactivity
• Alpha-smoke detector• Beta-controlling paper thickness;
tracers• Gamma-treating cancer; sterilising
equipment; tracers
Radioactive WasteRadioactive Wastecan be disposed of:1. in land-fill sites if it is low-level
waste2. by encasing it in glass and storing it
underground3. by reprocessing
How the Moon was formedHow the Moon was formed• Two planets collided• Their iron cores joined together to
form the Earth• Some less dense material broke off
and became the Moon, orbiting the Earth
Uses of satellitesUses of satellites• Telecommunications• Weather forecasting• Spying• Satellite navigation
The SunThe Sun• is a source of ionising radiation• produces solar flares, which• are clouds of charged particles• are sent out at high speed• produce strong magnetic fields
The UniverseThe Universeconsists of:• stars• planets• comets• meteors• black holes• large groups of stars called galaxies
Problems of manned Problems of manned spaceflightspaceflight
• Need huge amounts of fuel• Need large quantities of food and water• Journeys can take many years• Low gravity can affect health• Cosmic rays can be harmful• Must maintain a stable atmosphere• Must maintain suitable temperature
Unmanned spacecraftUnmanned spacecraft• can withstand conditions that are
lethal to humans• can send back information on:• temperature, magnetic field &
radiation• gravity, atmosphere and
surroundings
AsteroidsAsteroids can:
cause craters
throw up hot rocks
cause fires
create dust which blocks out sunlight
cause climate change
make species extinct
AsteroidsAsteroids• are rocks left over from the formation
of the Solar System• orbit between Mars and Jupiter
Evidence for past asteroid Evidence for past asteroid collisionscollisions
• Craters• Unusual elements in rock layers• sudden changes in fossil numbers in
layers of rock that are next to one another
CometsComets• are made from ice and dust• have highly elliptical orbits• come from deep space, beyond the
planets• travel faster as they approach the
Sun
Near-Earth Objects (NEOs)Near-Earth Objects (NEOs)• are asteroids or comets that could
collide with Earth• are watched through telescopes• tracked by satellites• could be knocked off course by
explosions if necessary
The Big BangThe Big Bang• The Universe started with an
enormous explosion called the Big Bang
• The Universe is still expanding
Evidence for the Big BangEvidence for the Big Bang• All galaxies are moving away from us• Distant galaxies are moving faster
than closer ones• Microwave radiation is detected from
all parts of the Universe
When medium-weight stars When medium-weight stars diedie
• they swell up to form a red giant• they throw out shells of gas called a
planetary nebula• shrink to form a white dwarf• cool to form a black dwarf
When heavy-weight stars When heavy-weight stars diedie
• they swell up to form a red giant• the core collapses and the whole star
explodes in a supernova• leaving behind a dense neutron star• sometimes the neutron star collapses
to form a black hole
Welcome Welcome To TIPS to doing well in To TIPS to doing well in
your your
B2 Science Examination!B2 Science Examination!
• You have attended the lessons• You have completed the revision• Now let’s have a few reminders
about exam technique
• Firstly the BIG QUESTION . . . Why do we have to do exams?
You have to give the examiner the proof that you have done the lessons and learnt lots of Science.
This is your chance to demonstrate this.
• On the exam paper will be a range of questions that cover the different topics e.g. collecting information on what lives where (ecology) or how to increase photosynthesis (food factory) etc.
• Some questions will be easy and you will all get those correct and some will be really challenging to stretch the very best of you.
• Check out how many marks are for each question
• So, you have had the breakfast, and you are about to do your best.
• Even now, there are teachers around to help you and during the exam the invigilators will make sure the whole process is as painless as possible.
• Your lessons have covered 8 topics and there will be 5 questions so you cannot be asked about everything. It will be your good luck if you are asked questions about your ‘best bits’!
• Let’s have a look at the style of question.
EcologyEcology• They often ask you a calculation here,
that’s why we use calculators!
• Look carefully at the DATA they give you and work out the average (mean)
• They usually want you to be critical about the data – is there ENOUGH of it?
EcologyEcologyquadrat number of
dandelions
1st 5
2nd 1
3rd 0
4th 2So, 5 + 1 + 0 + 2 = 8. To find the average you divide by the number of samples,so 8 ÷ 4 =2 for each quadratCritical comment ‘small sample size’
From Jan 08
EcologyEcology• Remember how to use KEYS to
identify your organismPicture a mini beast . . . .Does it have wings? Yes or NoIf No, does it have legs? Yes or NoIf No – it might be a worm!
From Jan 07
Grouping OrganismsGrouping Organisms• This involves classification, lots of
different groups, e.g. plants and animals, vertebrates and invertebrates etc.
• They like to ask about distinguishing features for a particular group.e.g. what are two features that only mammals have? FUR and MILK to feed the young
Grouping OrganismsGrouping Organisms• All mini beasts belong to the same
large group. Put a tick in the box next to that group.
From Jan 08
amphibians
invertebrates /
reptiles
vertebrates
The Food FactoryThe Food Factory• You have to know what plants need so
they can photosynthesise. . . . water. . . . carbon dioxide. . . . chlorophyll From Jan 07
• And the word equationwater + carbon dioxide glucose +
oxygenFrom Jan 08
The Food FactoryThe Food Factory• Photosynthesis is a special process
done by only green plants
• Remember it is linked to that other essential living process done by EVERY CELL . . . called . . . RESPIRATION, that releases energy!
Compete or DieCompete or Die• Successful PREY are found in large numbers so that some will survive!
• Successful PREDATORS raise more offspring
• Remember plants are busy competing as well, for? space light water minerals
Adapt to FitAdapt to FitWhen you have got masses of living things in one place, any individual that is better suited will do better, breed better etc.Gradually the features that are better suited become more common.Eventually you get a specialised organism that perfectly matches it’s habitat. e.g. polar bears in the Artic
Adapt to FitAdapt to Fit• Camels are adapted to live in the desert,
what are the ways they are adapted . . . .(3 marks) From Jan 07
fat in hump (1), for food store (1), large feet (1), to spread out load (1)long eyelashes (1), to stop sand getting in eyes (1) etcMake sure you write enough to get all 3 marks.
Survival of the FittestSurvival of the Fittest• Fossils are the remains of extinct
animals, suggest why the rest of the animal did not fossilise . . . . (1 mark) from Jan 08SUGGEST questions mean you can give any SENSIBLE solution. Many answers allowed such as:- too soft, decayed, decomposed, was eaten, biodegraded, rot, no bones, not hard.
Survival of the FittestSurvival of the Fittest• Describe how fossils are formed from
shells. (1 mark) from Jan 08DESCRIBE questions must tell the story clearly, so the examiner knows you have learnt the processes involved.
Possible answers: covered in sediment (1), empty shell filled with deposits (1), replaced by minerals (1)
Survival of the FittestSurvival of the Fittest• What does extinct mean?
. . . . None left alive
• What does endangered mean?. . . . Close to extinction
From Jan 07
Population out of ControlPopulation out of Control• This covers all the consequences to our
planet of us having such a large population
e.g. acid rainholes in the ozone layerglobal warming etc.
• Indicator species reflect the damage doneagain you might have to read and answer questions based on DATA given.Read it through more than ONCE.
SustainabilitySustainability• This covers all the ways we are trying to
put right the damage our large population is causingWhich TWO of these resources is finite?
» Fossil fuels» Minerals» Oxygen» Water» Wood
Minerals and Fossil Fuels
From Jan 08
Paints.Paints.• Paints contain:
– Pigment (gives it colour).– Binding medium (glues it to the wall).– Solvent (stops it sticking to the inside
of the tin.)
Paints.Paints.• Paints are colloids:
– Tiny particles mixed (NOT dissolved) in a liquid.
– Don’t separate because they’re so small.
Dyes and special paints.Dyes and special paints.
• Dyes used to be made form plants but now they are synthetic (man made).
• Thermo chromic paint:– Changes colour with heat.
• Phosphorescent pigments:– Absorb light energy, store it in their
molecules, and then release it.– In the olden days they were radioactive.
Construction materials.Construction materials.
• Cement is made from clay and limestone.– Add gravel and it makes concrete as well.– Reinforcing with iron bars like the twin towers
makes it a ‘composite material’.• Better to take sudden shocks like planes hitting
them, but the metal can rust or melt and cause problems.
Construction materials.Construction materials.
• Glass is made by melting Limestone, sand, and soda.
• Metals are extracted from ores.
• Bricks are made from clay just like your mug of tea in the morning.
Electrolysis.Electrolysis.• Electrolysis is splitting things up using
electricity.
• At the positive (+) anode electrons are lost as the copper atoms dissolve to form copper ions.Cu(s) ==> Cu2+(aq) + 2e-
Electrolysis.Electrolysis.• An electrolyte is a conducting melt or
solution of ions which carry the electric charge as part of the circuit.
– Like copper sulphate allowing the copper ions to float across.
• At the negative (-) cathode electrons are gained by the attracted copper(II) ions to form neutral copper atoms.Cu2+(aq) + 2e- ==> Cu(s)
Extraction of aluminium.
siphon
Graphite / carbon anodes
Molten aluminiumMolten electrolytebauxite + cryolite
Tanklinedwith
carboncathode
Moltenaluminiumout
Steelcase
Vented cover
Alloys.Alloys.• An alloy is a mixture of a metal and
any other element.
• Steel is an alloy of Iron and carbon, it can now absorb impacts better.
• Don’t forget brass, bronze, solder, and amalgam.
Different types of rock.Different types of rock.
• Sedimentary:– Soft crumbly, made from bits squished
together. E.g. limestone.
Different types of rock.Different types of rock.
• Metamorphic:– Made by heat and pressure on sedimentary
rocks, for long times. E.g. Marble.– Eventually they will melt and turn into
magma.
Different types of rock.Different types of rock.
• Igneous:– Magma below ground, Larva above ground.– Intrusive = slow cooling = large crystals =
underground.• (Basalt.)
– Extrusive = fast cooling = small crystals = above ground.• (Granite)
The structure of the The structure of the EarthEarth
• Crust:– Relatively thin and cool outer layer of the
Earth. – It is much cooler, harder, brittle and less
dense than the other layers.– Divided into sections or 'plates' which 'float'
and move on the mantle.
The structure of the The structure of the EarthEarth
• Mantle:– Almost solid but can move very slowly as
huge convection currents from radioactive decay in the core.
– It is relatively cold and rigid just below the crust, but lower down it is much hotter and non-rigid and so is able to flow.• Same thickness as Jam.
The structure of the The structure of the EarthEarth
• Core:– Mainly of iron, and nickel.– Its diameter is about half that of the Earth
(3500 km radius) and its is very hot and dense.
– Consists of an outer liquid layer and a solid inner layer.
– Heat is generated by radioactive decay.– The mainly iron core generates a magnetic
field through and around the Earth.
The structure of the The structure of the EarthEarth
• The lithosphere is the rigid, relatively cool crust, and the outer or upper part of the mantle. It is split into sections called plates.
Plate tectonicsPlate tectonics• Plates used to ‘jigsaw’ fit together.
– used to form Pangaea.
• Fossils match on opposite sides of the oceans
• Identical rock sequences all around the world.
• Plates moved by slow convection currents in the mantle.
Subduction of the oceanic Subduction of the oceanic plate, under the continental plate, under the continental
plate.plate.
• Notice the mid ocean ridge, the costal earthquakes, and the costal ‘spine’ of volcanoes.
VolcanoesVolcanoes
• Formed by molten rock cooling as it surfaces.
• Subduction of oceanic crust can cause volcanoes as well.– Also cause earthquakes.
• Volcanoes make igneous rocks.– Runny lava is safer as you can run away form
it.– Sticky lava forms bombs and volcanoes
explode.
How we got air we can How we got air we can breath.breath.
1. Volcanoes give out steam and CO2.• Steam later condensed as rain (for
centuries).• A billion years
How we got air we can How we got air we can breath.breath.
2. Green plants take CO2 in and produce O2.
• Forms fossil fuels.• Nitrogen gas is put into the air by bacteria
How we got air we can How we got air we can breath.breath.
3. Ozone layer forms.• Blocks out UV rays.• Complex organisms evolve.
• 78%N2; 21% O2; 0.035% CO2
Air pollution and acid rain.Air pollution and acid rain.• Acid rain;
– Made from sulphur dioxide and oxides of nitrogen, (sulphuric acid and nitric acid).
– Kills fish and plants, (so no food for other things to eat).
Air pollution and acid rain.Air pollution and acid rain.• Catalytic converters take Nitrogen
oxide out of car fumes but replace it with carbon dioxide.
– 2CO + 2NO → N2 + 2CO2
– poison + acid rain → harmless + global warming.
Air pollution and acid rain.Air pollution and acid rain.• CO2;
– Increases global temperature, by stopping the heat from escaping.
– More heat means more evaporation which means more rain.•Hot places are getting hotter.
– (droughts, and famines)•Wet places are getting wetter.
– (floods.)
Collision theory.Collision theory.• Reaction only happen when things
collide.• Higher rate of reaction means ‘an
increase in the number of successful collisions.’
• More collisions means more likely hood of a successful one happening.
• Faster / harder collisions make each collisions more successful.
Temperature.Temperature.• Temperature is a measure of the
kinetic energy of the particles in an object.
• Increasing the temperature makes the particles move faster.
• Faster collisions means more likely to react.
ConcentrationConcentration(or pressure in gases).(or pressure in gases).
• Particles more crowded together.• More collisions.• Higher likelihood of a successful
collision happening.
Powder / lump.Powder / lump.Surface area.Surface area.
• More of the particles CAN hit each other at any time.
• (Granulated sugar and a lump of sugar)
Catalysts.Catalysts.• Decrease the amount of energy
needed for a reaction to successfully happen.
1. Catalysts must not be changed or used up by the reaction.
2. Only work for certain reactions.
Rates.Rates.• Speeding it up.1. Heat it up.2. Make it more
concentrated / pressurised.
3. Increase the surface area (make it a powder).
4. Add a catalyst.
• Slowing it down.1. Cool it down.2. Make it less
concentrated / pressurised.
3. Decrease the surface area (make it a lump).
4. Don’t add a catalyst.