P2: Living for the Future

1
P2 Living for the Future

• Key points for revision (Higher)

2
Energy from the Sun

• The Sun
• is a stable source of energy
• transfers energy to the Earth as light and heat
• is a renewable source of energy

3
Energy from the Sun

• The Suns 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

4
Photocells

• transfer light into electricity
• produce direct current (DC)
• can operate in remote locations
• produce more power when there is
• a brighter light
• and a bigger area of cell exposed

5
Advantages of photocells

• low maintenance
• no need for power cables
• no need for fuel
• long life
• rugged
• use renewable energy resource
• no polluting waste

6
Disadvantages of photocells

• No power at night
• No / low power in bad weather

7
How a photocell works

• energy is absorbed by the photocell
• electrons are knocked loose from the silicon
  crystal
• the electrons flow freely in an electric current

8
How passive solar heating works

• short wavelength infrared passes through the
  transparent glass
• the bodies inside absorb the infrared
• the bodies emit long-wavelength infrared
• the long-wavelength infrared cannot pass through
  the glass, so the glass reflects it back into the
  room

9
Advantages of wind turbines

• use renewable energy
• rugged
• no chemical pollution

10
Disadvantages of wind turbines

• will not work when there is no wind
• can not work when it is too windy
• make a visual impact on the landscape
• take up a lot of land

11
Generating electricity

• Batteries produce direct current (DC)
• Generators produce alternating current (DC)
• A generator can produce more electric current
• by using a stronger magnet
• more coils of wire
• moving the magnet or coils faster

12
Generating electricity in a power 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

13
Transformers

• Increase or decrease voltage
• A higher voltage means a lower current so less
  energy is wasted in heating the electric cables

14
Energy equations

• fuel energy input waste energy output
  electrical energy output
• efficiency electrical energy output
• fuel energy input
• efficiency little number
• big number

15
Fuels 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

16
Equations

• power voltage x current
• (watts) (volts) (amps)
• energy power x time
• (kilowatt-hours) (kilowatts) (hours)

17
Radioactivity

• Ionising radiations from radioactive waste can
  cause cancer
• Uranium is a non-renewable fuel
• Plutonium
• is a waste product from nuclear reactors
• can be used to make nuclear bombs

18
Advantages of nuclear power

• No fossil fuels used
• Plenty of uranium available
• No greenhouse gases

19
Disadvantages of nuclear power

• High decommissioning costs when a nuclear power
  station is finished with.
• Pollution from fuel processing.
• Risk of radioactive leak.
• High maintenance costs.

20
Background Radiation

• Background radiation is around us all of the time
• Background radiation comes from
• rocks soil
• cosmic rays

21
Nuclear Radiation

• Alpha can travel a few cm in air
• is stopped by paper
• Beta can travel about a metre in air
• is stopped by a few mm of aluminium
• Gamma can travel a very long way in air
• is reduced by a few cm of lead

22
Radioactive Safety

• Wear protective clothing
• Use tongs dont touch sources
• Keep sources at a sensible distance
• Use radioactive materials for short amounts of
  time
• Label store the sources carefully

23
Uses of radioactivity

• Alpha-smoke detector
• Beta-controlling paper thickness tracers
• Gamma-treating cancer sterilising equipment
  tracers

24
Radioactive Waste

• can be disposed of
• in land-fill sites if it is low-level waste
• by encasing it in glass and storing it
  underground
• by reprocessing

25
Radioactive Waste

• remains radioactive for a long time
• is at risk from terrorism
• must be kept out of water supplies

26
Ionisation
An atom is ionised if it gains or loses electrons
When Alpha or Beta particles pass another atom,
they tend to pull electrons off it. We then say
that the atom is ionised. If it has lost
electrons, we call it a positive ion.
27
Magnetic fields
Bar magnet
Current-carrying coil
28
Earths Magnetic Field
Magnetic South pole
Magnetic North Pole
29
Cosmic Rays

• are fast-moving particles, which create gamma
  rays when they hit the atmosphere
• spiral round the Earths magnetic field to the
  poles
• cause the Aurora Borealis

30
How the Moon was formed
31
How 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

32
Uses of satellites

• Telecommunications
• Weather forecasting
• Spying
• Satellite navigation

33
The 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
• affect satellite communication
• affect electricity distribution

34
The Solar System
35
Gravity

• Every body that travels in a circle does so
  because it is acted on by a force towards the
  centre of the circle, called the centripetal
  force
• Gravity provides the centripetal force

36
The Universe

• consists of
• stars
• planets
• comets
• meteors
• black holes
• large groups of stars called galaxies

37
Light-year

• The universe is so big that a way of measuring
  very large distances is needed
• One light-year is the distance travelled by a
  beam of light in 1 year

38
Problems of manned spaceflight

• 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

39
Unmanned spacecraft

• can withstand conditions that are lethal to
  humans
• can send back information on
• temperature, magnetic field radiation
• gravity, atmosphere and surroundings

40
Unmanned spacecraft

• dont put human lives at risk
• are cheaper than manned craft
• are difficult to maintain because there is no one
  to carry out repairs and maintenance

41
Asteroids
Asteroids can cause craters throw up hot
rocks cause fires create dust which blocks out
sunlight cause climate change make species extinct
42
Asteroids

• are rocks left over from the formation of the
  Solar System
• orbit between Mars and Jupiter
• have not joined together to make another planet
  because the large gravitational field of Jupiter
  has prevented this from happening

43
Evidence for past asteroid collisions

• Craters
• Unusual elements in rock layers
• sudden changes in fossil numbers in layers of
  rock that are next to one another

44
Comets

• are made from ice and dust
• have highly elliptical orbits
• come from deep space, beyond the planets
• travel faster as they approach the Sun because
  the gravitational force gets stronger

45
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

46
The Big Bang

• The Universe started with an enormous explosion
  called the Big Bang
• The Universe is still expanding

47
Evidence for the Big Bang

• Red shift shows that all galaxies are moving away
  from us
• Red shift shows that distant galaxies are moving
  faster than closer ones
• Microwave radiation is detected from all parts of
  the Universe

48
Stars are born

• when clouds of gas and dust
• are compressed by huge gravitational forces to
  form a protostar
• the huge rise in temperature causes fusion to
  occur and hydrogen atoms join together (fuse) to
  make helium atoms, giving out massive amounts of
  energy

49
When medium-weight stars die

• 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

50
When heavy-weight stars die

• 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, which is so dense and has such a
  large gravitational field that not even light can
  escape

51
Welcome

• To TIPS
• to doing well in your
• B2 Science Examination!

52

• T. . . Trinity
• I . . . Improves
• P . . . Pupil
• S . . . Success

53

• You have attended the lessons
• You have completed the revision
• Now lets have a few reminders about exam
  technique

54

• 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.

55

• 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

56

• 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.

57

• 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!
• Lets have a look at the style of question.

58
Ecology

• They often ask you a calculation here, thats 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?

59
Ecology
From Jan 08
So, 5 1 0 2 8. To find the average you
divide by the number of samples, so 8 4 2 for
each quadrat Critical comment small sample size
60
Grouping 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

61
Grouping Organisms

• Lions and cheetahs are different species
• What is meant by the term species?
• (2 marks)
• . . . . These are organisms that can
  successfully reproduce (breed, mate) (1)
• AND . . . . The offspring are also fertile (1)
• From Jan 07

62
The Food Factory

• You have the knowledge THE EQUATION . . .
• water carbon dioxide ? glucose oxygen
• From Jan 08
• And as the balanced formula
• 6 H2O 6 CO2 ? C6H12O6 6O2
• From Jan 07

63
The 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!

64
The Food Factory

• What are the 3 conditions that help and sometimes
  limit photosynthesis
• . . . . more LIGHT
• . . . . higher TEMPERATURE
• . . . . more CARBON DIOXIDE

65
Compete or Die

• Successful PREY are found in large enough numbers
  so that some will survive!
• Successful PREDATORS raise more offspring
• Remember plants are busy competing as well, for?
• space
• light
• water
• minerals

66
Compete or Die

• The farmer gets fewer weeds in his bean fields
  than in his wheat fields.
• Suggest why. (1
  mark)
• . . . . . not enough minerals for weeds
• OR more competition for light
• OR more competition for water
• OR more competition for minerals
• From Jan 08

67
Adapt to Fit

• When 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 its habitat.
• e.g. polar bears in the Artic

68
Adapt 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), long eyelashes (1),
• large feet (1), to stop sand getting in eyes
  (1)
• for food store (1), to spread out load (1) etc
• Make sure you write enough to get all 3 marks.

69
Survival of the Fittest

• Fossils are the remains of extinct animals,
  suggest why the rest of the animal did not
  fossilise . . . . (1 mark) from Jan
  08
• SUGGEST 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.

70
Survival of the Fittest

• Describe how fossils are formed from shells.
  (1 mark) from Jan 08
• DESCRIBE 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)

71
Survival of the Fittest

• Darwins Theory of Natural Selection
• Sexual reproduction leads to variation
• Organisms with successful characteristics survive
• Survivors breed passing on the characteristic in
  the genes
• Over many generations organisms evole

72
Survival of the Fittest

• For Example
• Imagine a large group of grazing animals, all
  showing variation (slightly different to each
  other)
• Some individuals happen to have longer necks.
• They reach fresh food supplies, and they are more
  successful so breed
• The long neck genes get passed on
• Longer necked individuals eventually become a new
  species e.g. giraffes!

73
Population out of Control

• This covers all the consequences to our planet of
  us having such a large population
• e.g. acid rain,
• holes in the ozone layer,
• global warming etc.
• Indicator species reflect the damage done
• again you might have to read and answer
  questions based on DATA given.
• Read it through more than ONCE.

74
Sustainability

• This covers all the ways we are trying to put
  right the damage our large population is causing
• Blue whales are an endangered species, they are
  hunted because their bodies had many commercial
  uses.
• What was one commercial use . . . . (1 mark)
• food OR oil OR cosmetics OR glue

75
Sustainability

• Many people think that hunting of all types of
  whales should stop. Why is it difficult to stop
  all whale hunting? (1 mark) from
  Jan 08
• It is difficult to enforce OR seas to large to
  patrol
• OR not clear which country is responsible for
  different parts of the sea.

76

• Good Luck
• You have got the knowledge
• You have got the skills
• Now get the marks

77

• B2 Exam Revision

78
Paints.

• Paints contain
• Pigment (gives it colour).
• Binding medium (glues it to the wall).
• Solvent (stops it sticking to the inside of the
  tin.)

79
Paints.

• Paints are colloids
• Tiny particles mixed (NOT dissolved) in a liquid.
• Dont separate because theyre so small.

80
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.

81
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.

82
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.

83
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) gt Cu2(aq) 2e-

84
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- gt Cu(s)

85
Copper purification.
86
Extraction of aluminium.
87
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.
• Dont forget brass, bronze, solder, and amalgam.

88
Different types of rock.

• Sedimentary
• Soft crumbly, made from bits squished together.
  E.g. limestone.

89
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.

90
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)

91
Dont forget the currents in the magma moving the
plates.
92
(No Transcript)
93
The structure of the Earth

• 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.

94
The structure of the Earth

• 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.

95
The structure of the Earth

• 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.

96
The structure of the Earth

• The lithosphere is the rigid, relatively cool
  crust, and the outer or upper part of the mantle.
  It is split into sections called plates.

97
Plate 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.

98
Subduction of the oceanic plate, under the
continental plate.

• Notice the mid ocean ridge, the costal
  earthquakes, and the costal spine of volcanoes.

99
Volcanoes

• 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.

100
How we got air we can breath.

• Volcanoes give out steam and CO2.
• Steam later condensed as rain (for centuries).
• A billion years

101
How we got air we can breath.

• Green plants take CO2 in and produce O2.
• Forms fossil fuels.
• Nitrogen gas is put into the air by bacteria

102
How we got air we can breath.

• Ozone layer forms.
• Blocks out UV rays.
• Complex organisms evolve.
• 78N2 21 O2 0.035 CO2

103
Life is all about cycles.

• Water.
• Nitrogen.
• Rocks.
• Carbon.

104
(No Transcript)
105
(No Transcript)
106
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).

107
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.

108
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.)

109
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.

110
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.

111
Concentration(or pressure in gases).

• Particles more crowded together.
• More collisions.
• Higher likelihood of a successful collision
  happening.

112
Powder / lump.Surface area.

• More of the particles CAN hit each other at any
  time.
• (Granulated sugar and a lump of sugar)

113
Catalysts.

• Decrease the amount of energy needed for a
  reaction to successfully happen.
• Catalysts must not be changed or used up by the
  reaction.
• Only work for certain reactions.

114
Rates.

• Speeding it up.
• Heat it up.
• Make it more concentrated / pressurised.
• Increase the surface area (make it a powder).
• Add a catalyst.

• Slowing it down.
• Cool it down.
• Make it less concentrated / pressurised.
• Decrease the surface area (make it a lump).
• Dont add a catalyst.

115
Rate volume of gas produced time taken.