B6 Notes - OCR Gateway Science

Notes on all the items that are listed in the student checklists (well most of the points because some of them were too hard). Hope you find this useful!!

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  • Created by: Clairee
  • Created on: 13-06-11 13:00
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B6a ­ Understanding Bacteria!
Compare the structure of bacterial cells with plant and animal cells.
Bacteria do not have a proper nucleus they have a nucleoid (which unlike a nucleus doesn't have a
membrane around it).
Bacteria do not contain mitochondria, chloroplasts or a vacuole.
A bacteria cell
Capsule ­ a sticky coat that stops the bacterium from drying out (not all bacterium have this)
Ribosomes ­ small spherical structures that build protein from amino acids
Nucleoid ­ contains most of the bacterium's DNA (no membrane around it)
Flagellum ­ tails that enables the bacteria to swim (not all have this)
Cell Wall ­ a rigid protective wall that gives the cell its shape and stops it from bursting
Cell Surface Membrane controls which substances can enter and leave the bacterium.
How bacteria reproduce
Bacteria reproduce asexually ­ BINARY FISSION
The cell splits in two.
The chromosomes are copied
The cell grows
The cells then divides into two cells
Why are bacteria able to exploit a wide range of habitats?
Some bacteria can make their own organic nutrients (a form of photosynthesis) instead of having to
consume them
This means bacteria can survive on a wide range of energy sources

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Products that are made using bacteria
1. Cheese
2. Yoghurt
3. Beer
4. Wine
5. Olives/Pickles
Shape of Bacterial Cells
Rod shaped
Spherical shaped
Spiral shaped
Curved Rod shaped
How can bacteria be grown industrially for the use of man?
A bacteria left in ideal conditions can split into 2 every 20 mins
Bacteria can be grown in large tanks called fermenters
Fermenters can be used to produce medicines, enzymes, fuels and food
Making yoghurt
1. Sterilisation of the equipment using bleach or steam
2.…read more

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B6b ­ Harmful Microorganisms
Disease Cause? How is it spread?
Food Poisoning Salmonella, E Coli (Rod shaped Eating raw or undercooked food
bacteria) contaminated with faeces, poor personal
hygiene.…read more

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Some diseases that can be caused are cholera (broken sewage pipes), dysentery (broken sewage
pipes) and food poisoning (not fridge = decaying food).
Stages of an infectious disease
7. Pathogen enters your body, (e.g. throat)
8. Incubation Period pathogen reproduces rapidly and numbers increase but there are not
symptoms because not enough of the pathogen
9. Immune system starts to respond.
10. Pathogen produced toxins
11. Symptoms affect you (sore throat, fever) depending on type of pathogen.…read more

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B6c ­ Microorganisms factories for the future?
Yeast is classified in the kingdom of Fungi
Yeast cells reproduce asexually by budding
Fermentation is the breakdown of sugars by yeast in the absence
of oxygen.…read more

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How can yeast be used to treat water contaminated by sugars?
The yeast will break down the sugars, so the sugar will not be left in the water from food processing
How are different strains of yeast useful to brewers?
Different strains of yeasts can tolerate different levels of alcohol, so some yeast will be able to make a
more concentrated beer.
Pure alcohol is separated from the fermented sugar by boiling and condensing the vapours (the
alcohol has a lower boiling point).…read more

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B6d ­ Biofuels
Advantages of Biofuels over Fossil Fuels
Biofuels Fossil Fuel
Once burned more can be Takes millions of years to
grown, it is a sustainable be made
Return the same amount Add carbon dioxide to the
of CO2 to the air as it took atmosphere
to grow it (carbon neutral)
Methane is a greenhouse Produces other polluting
gas but Biofuels are gases
overall cleaner
Don't produce particulates Particulates can cause
so are less dangerous to health issues
your health.…read more

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Why do most plants rely on soil?
They need the soil for water
They need oxygen
They need the minerals from the soil
Groups of Living Organism that Soil Contains
Herbivores (slugs, snails and wireworms), eat plant material
Detritivores (earthworms, millipedes, springtails), feed on dead organic material
Carnivores (centipedes, spiders and ground beetles) feed on other animals
Chemical Elements that are recycled in the soil
Carbon ­ the basis for all organic molecules
Sulphur and Phosphorus ­ used to make proteins.…read more

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helped me alot :D really useful notes and covered the whole topic :D could you maybe do a B5 and B4 one :D that would be really useful!!!!!!!!!!!!!!!!!!!!


Really good!! :D

joose marley



really helpful!! Thank you so much! :)


Really Good. Thanks

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