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?

Fossils and the similarities between living things

Describe selective breeding and give an example?

Selecting which pigs (for example) to breed because they produce the right meat

Briefly describe Natural selection

Survival of the fittest (and passing on your genes

Why is the idea of competition important

If animals compete with each other only the most successful will survive to pass on their genes

Why did Darwin’s ideas take time to be accepted

Because people believed that the Bible was factually true

What is a mutation?

A sudden random change in the genes

What were the first living things like?

Very simple – molecules that could copy themselves

What are the advantages and disadvantages of being multicellular?

Different cells do different jobs but they need to be able to communicate

What are the body’s two main communication systems?

Hormones and nervous system

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

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

how do humans cause the extinction of other organisms?

By destroying or disrupting natural environments or food supplies

C3 Food Matters - revision

Why do plants need Nitrogen in the soil?

To make protein

Why do we need to keep adding fertilizer to our fields?

To replace nitrogen and other minerals needed for growth

What are the two different approaches to modern farming?

Intensive – lots of fertiliser and pesticides

Organic – none of the above

What are pesticides?

Chemicals used to kill animals and diseases that damage the crops

How can we control pests without using chemicals?

Natural predators like ladybirds

What is meant by sustainability?

A process is sustainable if it can continue without harming the earth.

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

What are the 5 main nutrients and what do they do?

Carbohydrates – for energyProteins – for growth and repairVitamins & minerals – to keep healthyFats – store energy

Why do large molecules like starch need to be digested?

So they can be dissolved and absorbed into the blood

What is a food allergy

When someone has a reaction to a particular food eg peanuts.

What happens to excess amino acids in our bodies?

Broken down into urea

What do the kidneys do?

Urea and excess water is removed and stored in the bladder

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

What is a risk factor for diabetes

Being overweight or obesity

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

P3 Material choices - revision

What do radioactive materials produce and what does this mean?

Produce ionising radiation which can damage living tissues

what are the three types of ionising radiation?

Alpha beta gamma

what are the properties of the 3 types of ionising radiation?

Alpha – low penetration – high ionisation

Gamma – high penetration – low ionisation

what is the difference between irradiation and contamination?

Irradiation – radiation goes through itContamination – contains something

that is making radiation

what affects the radiation dose that you could receive?

Time, how close you are (proximity) and type of radiation

how does ionising radiation affect living cells?

Breaks molecules like DNA and can lead to cancer

describe the structure of an atom

Small dense nucleus (protons & neutrons) surrounded by cloud of electrons

what are isotopes?

Atoms that have a different number of neutrons than normal – often radioactive

what is meant by half life?

The time taken for the radioactivity to drop to half its value

give some uses of ionising radiation.

Medical imaging, sterilising, treating cancer

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

what is nuclear fission and what is it used for?

Splitting heavy elements like uranium to release heat energy

what are the stages of electricity production in a power station?

Heat released 2. Water boiled 3. Steam turns turbines 4. Generator turned

What do we mean when a resource is sustainable?

It will never run out and the environment will not be ruined

What is the precautionary principle?

Better safe than sorry

why are nuclear power stations better than coal-fired power stations?

Don’t produce CO2

why are coal-fired power stations better than nuclear power stations?

Don’t produce radioactive waste

What is radon gas and how do we protect ourselves against it?

Produced by radioactive rocks – we should keep our houses well ventilated