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    1. Llegal, recreation (1)

    2. Changes chemical reactions, causes withdrawal symptoms (1)

    3. Independent company - not associated with the drug company (1)

    4. Unbiased (1)

    5. Effects nicotine, which is the same area as alcohol in the brain. Reduces pleasure, more likely to drink less (2)

    6. Boys drink beer, cider but the girls drank more wine, alcopop and spirits. (2)

    7. Not all boys drink because...(2)

    8. Carbohydrates --> Energy, Protein --> Growth + repair, Fat --> Warmth + energy, Fibre --> helps digestive system, Calcium --> strong bones and teeth, Water --> Hydrated the body (6)

    9. Temperature sensor - more accurate/easier to read because digital (1)

    10. It increased because micro organisms break down grass, respire and release CO2 This is trapped because of cotton wool so it accumulates and increases (2)

    11. It levels off at 20% because either not oxygen left for microorganisms to respire or all of the grass has been decomposed so the microorganisms have nothing left to feed on to respire (not sure) (1)

    12. Receptor (e.g eyes/tongue/nose/skin/ears) detect stimuli and pass on an impulse. Effectors (e.g muscles/glands) receive an impulse and respond by contracting/releasing hormones (4)

    13. Synapse - junction/small gap between two nerve endings/neurone (2)

    14. Neurotransmitters diffuse through the synapse, attach onto nerve ending and continues pulse (2)

    15. Sense organ using spinal chord - skin (1)

    16. Mean speed = 80/50 = 1.6 (2)

    17. Why is brain (without relay neurones) faster than spine? Less time wasted for impulses to be passed through the relay so it travels faster than the spine because of a shorter distance (2)

    18. Biomass is lost through waste/energy/heat/respiration/movement (2)

    19. There is a large amount of snails (200) as opposed to thrush (2) meaning they have less competition and ate more snails this more biomass (2)

    20. It is a scatter graph because it is comparing two sets of data (1)

    21. Higher percentage of no striped snails in woodlands but low percentage in grassland. Whereas with the light coloured snails, there's a higher percentage in grassland and low percentage in woodlands. (2)

    22. Woodland snails are better adapted because they are camouflaged (1)

    23. Horses foot size increased, amount of foot touching the floor decreased (2)

    24. Foot has a larger surface area so less pressure on soft mud so they don't sink into the ground (2)

    25. Variation in genes/mutations, better characteristics allow it to survive better and breed so their genetic material are passed onto the next generations. (4)

    26. Advantages 1. Males are released, they don't feed of blood so they don't cause malaria. 2. They reproduce so the children die before they become female adults and reduce malaria outbreak

    27. Disadvantages 1. Millions are released which could disrupt food chain, may even reduce biodiversity. 2. There could be long term side effects

    28. Overall they should/shouldn't release the mosquitos because... (4)

    29. Cut the gene using an enzyme from the DNA of the bacteria. Cut the DNA, using an enzyme, of the mosquito and insert the gene into it. Put the cell back into... (3)

    30. First part of the food chain are producers i.e plants (2)

    31. Mayfly larvae (animal) - water pollution (1) 32. Oxygen meter/rat tailed maggots/sludge worms for water pollution (1) 60 marks
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