biology paper 2

• IVF Process

  1. First, a woman is given FSH and LH to stimulate their eggs to mature.
  2. These eggs can then be collected from the woman's ovaries. Sperm is also collected from the male.
  3. The eggs are then fertilised by the sperm.
  4. These fertilised eggs are then left to grow into embryos in a laboratory incubator.
  5. Once the embryos are large enough, they are transferred to the women's uterus, so that they can develop into a foetus.
• 3 ways that scientists can study the brain

  study people with brain damage

  electrically stimulate different parts of the brain

  scan the brain, using CT, PET, MRI scans
• decay required practical part 1

  1. label a boiling tube 'lipase' and add 5 cm³ of the lipase solution
  2. label another boiling tube 'milk' and add 5 drops of the cresol red solution
  3. use a dropping pipette to add 5 cm³ of milk to the 'milk' solution
  4. use another pipette to add 7 cm³ of sodium carbonate solution to the 'milk' boiling tube. this solution should be purple
  5. put a thermometer in the 'milk' boiling tube
  6. set up a water bath to your first chosen temperature
  7. put both boiling tubes into the water bath, wait for the contents to reach the same temperature as the water bath
• decay required practical part 2

  1. use a pipette to transfer 1 cm³ of the lipase from the 'lipase' boiling tube to the 'milk' tube
  2. start the stop clock
  3. stir the contents of the 'milk' boiling tube until the solution turns yellow
  4. record the time taken for the colour to change to yellow in seconds
  5. repeat this investigation for different temperatures of the water bath 3 times each and calculate a mean
  6. record your results in a table and plot a graph
• reaction time required practical

  1. student A sits with their elbow resting on the edge of the table
  2. student B holds a ruler with the bottom of the ruler level at the top of student A's hand
  3. student B drops the ruler, without telling student A
  4. student A catches the ruler and records the distance
  5. steps 1 to 4 are repeated to calculate a mean
  6. use a conversion table to convert your ruler measurement into reaction times
  7. make the change that you are investigating
  8. repeat steps 1 to 8
• quadrats required practical

  1. place a quadrat on the ground randomly, a computer can generate random coordinates
  2. this removes bias
  3. count the number of species within the frame
  4. repeat and calculate the mean number of organisms per quadrat
  5. could be repeated in another sample area and then results can be compared
• transects required practical

  1. lay your tape measure between the two points
  2. place your quadrat down at intervals, every 2m
  3. record the type/number of species in the quadrat
• germination required practical part 1

  1. put cotton wool into three petri dishes
  2. add the same volume of water to each dish
  3. add ten seeds to each dish and put them in a warm place where they wont be disturbed
  4. allow the seeds to germinate and add more water if the cotton wool dries out
  5. ensure that all petri dishes have the same number of seeds and remove any seeds if necessary
  6. one petri dish will sit in full light on a windowsill, the second will be in a dark cupboard and the final one will be placed in partial light
• germination required practical part 2

  1. every day for one week, measure the height of each seedling and record the reults in a table
  2. calculate the mean height of the seedlings each day
  3. compare the mean heights in the three different locations
• habitat


  where an organism lives
• population


  all the organisms of a particular species that live in that habitat
• community


  all the populations of different species that live together in that habitat
• biotic factors


  living factors of the environment (availability of food, number of predators)
• abiotic factors


  non-living factors of the environment (temperature, soil pH)
• ecosystem


  the interaction of a community of living organisms with the non-living parts of their environment
• interdependence


  all species depend on other species in some way
• extremophile


  microorganisms that live in extreme environments, such as those with high temperatures, pressures or salt concentrations
• producers → primary consumers → secondary consumers → tertiary
• 3 processes that release carbon dioxide into the atmosphere

  decomposition

  respiration

  combustion
• factors that affect the rate of decay

  oxygen availability

  temperature

  water content
• what does adrenaline do?

  increases heart rate

  increases blood pressure

  increases blood flow to muscles

  increases blood glucose levels
• thyroxine


  increases your metabolic rate
• alleles 


  different versions of a particular gene
• phenotype


  the characteristics an organism has as a result of their genotype
• increase the risk of mutations

  carcinogens like those found in cigarette smoke

  ionising radiation such as x-rays or gamma rays
• gregor mendel

  studied genetic inheritance with pea plants
• charles darwin


  survival of the fittest, natural selection and evolution
• jean baptise-lamark


  organisms could develop new traits during their lifetime
• cornea


  transparent layer at the front of the eye which refracts light
• pupil


  a gap that light passes through to reach the lens
• factors affecting food security

  rising populations

  diets change

  new pets and pathogens can kill livestock

  environmental changes

  conflicts like war that disrupt the transportation and production of food

  expensive
• why is the fossil record incomplete?

  some fossils that were formed long ago may have been destroyed

  some of the organisms were soft-bodied so they did not fossilate well
• kingdom → phylum → class → order → family → genus →species
• three domain classification 


  bacteria

  eukaryota

  archaea