b3 life on earth - revision
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B3 Life on Earth - revision. What makes organisms members of the same species?. If they can mate and produce fertile young. What are the two different causes of variation in living things?. Genes and environment. What is the evidence for evolution?. - PowerPoint PPT PresentationTRANSCRIPT
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B3 Life on Earth - revision
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What makes organisms members of the same species?
If they can mate and produce fertile young
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What are the two different causes of variation in living things?
Genes and environment
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What is the evidence for evolution?
Fossils and the similarities between living things
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Describe selective breeding and give an example?
Selecting which pigs (for example) to breed because they produce the right meat
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Briefly describe Natural selection
Survival of the fittest (and passing on your genes
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Why is the idea of competition important
If animals compete with each other only the most successful will survive to pass on their genes
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Why did Darwin’s ideas take time to be accepted
Because people believed that the Bible was factually true
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What is a mutation?
A sudden random change in the genes
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What were the first living things like?
Very simple – molecules that could copy themselves
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What are the advantages and disadvantages of being multicellular?
Different cells do different jobs but they need to be able to communicate
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What are the body’s two main communication systems?
Hormones and nervous system
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What do we mean when we say humans and chimps have a common ancestor?
Humans have not evolved from chimps but we have both evolved from something else
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How long ago were the first hominids and what made them different from other apes?
Between 1.5 and 4 million years ago – it walked upright
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how do humans cause the extinction of other organisms?
By destroying or disrupting natural environments or food supplies
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C3 Food Matters - revision
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Why do plants need Nitrogen in the soil?
To make protein
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Why do we need to keep adding fertilizer to our fields?
To replace nitrogen and other minerals needed for growth
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What are the two different approaches to modern farming?
Intensive – lots of fertiliser and pesticides
Organic – none of the above
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What are pesticides?
Chemicals used to kill animals and diseases that damage the crops
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How can we control pests without using chemicals?
Natural predators like ladybirds
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What is meant by sustainability?
A process is sustainable if it can continue without harming the earth.
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What chemicals are added to foods and what do they do?
Preservatives – stop it going offColours – make it look niceFlavourings – make it taste niceEmulsifiers & stabilisers – stop it
separating
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What are the 5 main nutrients and what do they do?
Carbohydrates – for energyProteins – for growth and repairVitamins & minerals – to keep healthyFats – store energy
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Why do large molecules like starch need to be digested?
So they can be dissolved and absorbed into the blood
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What is a food allergy
When someone has a reaction to a particular food eg peanuts.
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What happens to excess amino acids in our bodies?
Broken down into urea
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What do the kidneys do?
Urea and excess water is removed and stored in the bladder
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What is the difference between the two types of diabetes?
Type 1 In younger people – controlled by insulin
Type 2 In older people – controlled by diet, medicine and sometimes insulin
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What is a risk factor for diabetes
Being overweight or obesity
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What is the purpose of the FSA and what do they do?
Food standards agency – encourage people to eat healthily by promoting labelling and good practice
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P3 Material choices - revision
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What do radioactive materials produce and what does this mean?
Produce ionising radiation which can damage living tissues
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what are the three types of ionising radiation?
Alpha beta gamma
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what are the properties of the 3 types of ionising radiation?
Alpha – low penetration – high ionisation
Gamma – high penetration – low ionisation
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what is the difference between irradiation and contamination?
Irradiation – radiation goes through itContamination – contains something
that is making radiation
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what affects the radiation dose that you could receive?
Time, how close you are (proximity) and type of radiation
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how does ionising radiation affect living cells?
Breaks molecules like DNA and can lead to cancer
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describe the structure of an atom
Small dense nucleus (protons & neutrons) surrounded by cloud of electrons
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what are isotopes?
Atoms that have a different number of neutrons than normal – often radioactive
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what is meant by half life?
The time taken for the radioactivity to drop to half its value
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give some uses of ionising radiation.
Medical imaging, sterilising, treating cancer
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what are the three categories of radioactive waste and how are they disposed of?
LLW/ILW/HLW – High/intermediate/low
It is sealed in glass or concrete and buried
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what is nuclear fission and what is it used for?
Splitting heavy elements like uranium to release heat energy
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what are the stages of electricity production in a power station?
Heat released 2. Water boiled 3. Steam turns turbines 4. Generator turned
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What do we mean when a resource is sustainable?
It will never run out and the environment will not be ruined
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What is the precautionary principle?
Better safe than sorry
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why are nuclear power stations better than coal-fired power stations?
Don’t produce CO2
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why are coal-fired power stations better than nuclear power stations?
Don’t produce radioactive waste
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What is radon gas and how do we protect ourselves against it?
Produced by radioactive rocks – we should keep our houses well ventilated