GCSE Biology

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ghoran
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GCSE Biology
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2012-06-08 06:49:54
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  1. what is meant by a pandemic
    an outbreak of disease worldwide
  2. explain why the mutation of the influenza virus might cause another influenza pandemic
    flu viruses are always mutating , producing new strains . Because the new strain is so different , people will have no immunity to it , so the virus is not recognised by their white blood cells This may cause an epidemic or pandemic because people travel from country to country and spread disease . New vaccines or antiviral drugs not yet developed
  3. explain how the MMR vaccine protects children from mumps , measles and rubella
    • vaccine contains a dead form of the pathogen
    • stimulates antibody production by white blood cells
    • antibodies kill pathogen
    • antibodies qiuckly produced on reinfection
  4. explain how the MRSA bacterium has developed resistance to antibiotics
    • a mutation occured
    • bacteria no longer recognised by antibiotics
  5. why is MRSA causing problems in hospitals
    • it is resistant to most antibiotics
    • easily passed on
    • patients are ill therfor they are less able to combat disease
  6. the pioneer in methods of treating infections in hospitals was Ignaz Semmelwiss . He observed that women whose babies were delivered by doctors in hospital had a death rate of 18% from infections caught in the hospitral . Women whose babies were delivered by midwives in the hospital had a death rate of 2% . He observed that doctors often came straight from examining dead bodies to the delivery ward . In a controlled experiment he made doctors wash their hands in chloride of lime solution before delivering the babies . The death rate fell to about 2% . Explain why the death rate fell
    chloride of lime killed bacteria picked up from corpses
  7. the pioneer in methods of treating infections in hospitals was Ignaz Semmelwiss . He observed that women whose babies were delivered by doctors in hospital had a death rate of 18% from infections caught in the hospitral . Women whose babies were delivered by midwives in the hospital had a death rate of 2% . How could his results be used to reduce the spread of MRSA in a modern hospital
    it could make doctors wash their hands after contact with patient so MRSA not transferred to other patients
  8. why do bacteria and viruses make us feel ill
    • bacteria produce toxins/poisons
    • viruses damage our cells or toxins are released from the cell
  9. name one factor other rthan diet , which affects the level of cholestrol in the blood
    exercise/metabolism/hereditery/HDL LDL ratio
  10. other than increasing fitness , give two reasons why regukar exercise is important in maintaining a healthy body
    • it burns off energy that would otherwise be stroed as fat
    • increases the metabolic rate
    • decreases blood pressure
    • lower risks of heart disease , arthritis and diabetes
  11. describe the relationship between the types of lipoprotein in the blood and heart disease
    • balance between the 2 important for good health
    • high LDL causes heart disease
    • high HDL reduces heart disease
  12. what is meant by metabolic rate
    rate of chemical reactions inside the bodies cells
  13. other than heart disease name 2 conditions which are linked to obesity
    • any 2 of :
    • arthritis
    • diabetes
    • high blood pressure
    • strokes
    • breathing difficulties
  14. what does the term energy flow decsribe in an ecosystem
    the movement of energy , which originally comes from the sun and is passed through one organism to another
  15. explain why there cannot be an unlimited number of trophic levels
    • energy is always lost at each trophic level so eventually there would be no energy if trophic levels were unlimited
    • Simply stated, for there to be an unlimited number of trophic levels, there would have to be an unlimited number of species, each of which eats its neighbor further down thefood chain. However, there is a finite number of species
  16. Red squirrels live in trees . They eat seeds from the cones of conifer trees . Squirrels store cones in "larders" on the ground . These larders provide food through the winter . Each red squirrel makes an defends one larder . Scientists counted the number of larders in different areas to estimate the number of squirrels . This could have led to an inaccurate estimate of the number of squirrels explain how
    • squirrels could have moved on or died
    • there could be young squirrels that havent made a larder yet
  17. the san gazelle lives in the Arabian Desert where temperatures often reacg 45°C . During the dry season , the sand gazelle's liver and heart shrink in size . This reduces the amount of oxygen the body needs . Suggest how this helps the animal to conserve water
    • breathing rate less
    • less water lost via breath
    • less water from respiration
  18. most penguins live in cold climates . The modern penguin best adapted for cold conditions is the emperor penguin . Scientisits have found fossils of a giant penguin whicg they have called icadyptes . The scientist were suprised to discover that icadyptes lived in warm seas at a time when the earths climate was much warmer than it is now . Explain why the scientists were suprised
    • similar size to emperor penguin
    • large size is adaption to cold climate
    • small surface area to volume ratio which reduces heat loss
  19. seals are adapted for life in the sea . Give two ways the seal is adapted for swimming
    • it is strealined/smooth
    • it has flippers
    • it has a flattened/long/large/powerful tail
  20. students investigated the distribution of of two plant species near a busy road describe how apparatus could be used to obtain results
    • use a transect
    • sample every metre
    • count the number of plants in the quadrat
  21. why might plants not grow on the roadside
    • there may be weedkiller on the roadside
    • they may be sensitive to pollution
  22. why might plants grow on the roadside
    uses carbon dioxide from traffic which enhances photosynthesis
  23. gardeners often cover trays of cuttings with large polythene bags suggest an advanatge of this
    it prevents a loss of moisture and so the cuttings will not wilt and dry out
  24. tetra is the first monkey to be cloned
    a sperm ans egg were combined and the resulting embryo was allowed to split into two cells than four then eight cells
    at the eight cell egg stage , the embryo itself was split by scientists to produce four two-cell embryos
    the four embryos were then implanted into surrogate mothers . three of the embryos did not survive . The forth tetra was born 157 days later . her name means one of four
    explain why this method could produce several identical monkeys
    • all the monkeys were from the same embryo
    • each embryo has identical genetic information
  25. tetra is the first monkey to be cloned a sperm ans egg were combined and the resulting embryo was allowed to split into two cells than four then eight cellsat the eight cell egg stage , the embryo itself was split by scientists to produce four two-cell embryos the four embryos were then implanted into surrogate mothers . three of the embryos did not survive . The forth tetra was born 157 days later . her name means one of four
    suggest 2 reasons why these monkeys would be valuable in trials of new treatments for human diseases
    • any two from
    • experimental subject and control are identical so it will be a fair test
    • monkeys are similar to humans , so effect of drugs likely to be similar
    • all identical so will have same reaction to drug/disease
    • it is better than catching wild ones
  26. many people are opposed to the growing of herbicide resistant crops produced this way . suggest one reason why
    • any one from
    • herbicide resistant gene may be picked up by weeds creating a herbicide resistant weed
    • lack on knowledge about effects of GM food on health
  27. why are identical twins not clones of their parents
    • genetic material is provided from two parents
    • sexual reproduction
  28. many insecticides conatin active ingredients called pyrethrins . These are extracted from pyrethrum daisies . These plants are grown in Kenya , a developing country in Africa
    An American biotechnology company has now transferred the gene for making a specific pyrethrin to brwers yeast . This can be grown easily , so pyrethrin can be produced cheaply . However insect populations can build up resistance to specific pyrethrins
    evalutae the use of brwers yearst to produce pyrethrins
    • advanatges : large scale , cheaper , quick to produce
    • disadvanatges : loss of farmers income , loss of foreign exchange , less work in Kenya , mass use of a particular pyrethrin
    • conclusion i don't think we should produce pyrethrins from brewers yeast despite the production method being non-seasonal because it can allow for insect populations to become resistant

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