biology key concepts triple paper 1

• osmosis is...

  the net movement of water molecules across a partially permeable membrane, from an area of higher water concentration, to an area of lower water concentration
• diffusion is...

  the overall net movement of particles from an area of higher concentration to an area of lower concentration
• how do you test for lipids?


  -emulsion test

  -shake with ethanol until it dissolves

  -pour into water

  -if lipids present they will precipitate out and create cloudy emulsions
• how to test for [reducing] sugars?

  • add Blue Benedict's solution to sample
  • if sugars present, coloured precipitate will form
  • blue->green->yellow->orange->brick red
  • the higher the concentration of sugars, the further the colour change
• how to test for starch?

  • add iodine to the solution
  • it starch present, it changes from brown-orange to blue-black
• how to test for proteins?

  • biuret test
  • add pottasium hydroxide to make it alkaline
  • then add blue copper sulfate
  • if Protein is Present it turns Purple
• how do enzymes make biochemical reactions more likely to happen?

  they lower the activation energy
• what is the active site[of an enzyme]?

  where the enzyme joins to the substrate to catalyse a reaction
• describe the enzyme and substrate relationship

  • lock and key mechanism
  • enzymes are highly specific to their substrates
• if the substrate doesn't fit the active site then...

  the reaction won't be catalysed
• what are enzymes and what do they do in reactions?

  • proteins that act as biological catalysts
  • speed up rate of chemical reactions
• how does temperature affect rate of reaction in enzymes?

  • initially higher temp increases rate of reaction
  • if too hot, it changes the shape of the active site = denatured
  • substrate won't fit anymore
• where is the enzyme amylase found and what does it catalyse?

  • saliva and small intestine
  • breaks down starch to small sugars
• where is the enzyme catalase found and what does it catalyse?

  • found in most cells esp liver cells
  • breaks down hydrogen peroxide to water and oxygen
• where is the enzyme starch synthase found and what does it catalyse?

  • found in plants
  • synthesis of starch from glucose
• picometre [pm] in m

  x 10-12 m
• where is the enzyme DNA polymerase found and what does it catalyse?

  • found in nucleus
  • synthesis of DNA from its monomers
• nanometre [nm] in m


   x 10-9 m
• micrometre [µm] in m


  x 10-6 m
• millimetres [mm] in m


  x 10-3 m
• magnification = ?/?


  image size/real size
• total magnification= ? x ?

  eyepiece lens[magnifiction] x objective lens [magnification]
• what do microscopes do to an image?

  • magnify
  • increase resolution
• how does pH affect the rate of reaction in enzymes?

  if below or above the optimum it changes shape of active site=denatured
• what does the enzyme carbohydrase convert?

  carbohydrates -> simple sugars
• what does the enzyme lipase convert?

  lipids-> glycerol and fatty acids
• what does the enzyme protease convert?

  proteins-> amino acids
• how does substrate concentration affect rate of reaction in enzymes?

  • higher the concentration, the more active sites are full, the faster the reaction
  • but eventually all active sites are full, adding more makes no difference
• what are specialised cells?

  cells with structure that makes them adapted to their function
• which organism(s) is the nucleus found [bacteria, animals and plants]

  animals, plants
• which organism(s) is the cell membrane found [bacteria, animals and plants]

  bacteria, animals and plants
• which organism(s) are mitochondria found [bacteria, animals, plants]

  animals, plants
• which organism(s) are ribosomes found [bacteria, animals, plants]

  bacteria, animals and plants
• which organism(s) are cell walls found [bacteria, animals, plants]

  bacteria, plants
• which organism(s) are chloroplasts found [bacteria, animals, plants]

  plants
• which organism(s) are permanent vacuoles found [bacteria, animals, plants]

  plants
• which organism(s) is chromosomal DNA found [bacteria, animals, plants]

  bacteria
• which organism(s) is plasmid DNA found [bacteria, animals, plants]

  bacteria
• which organism(s) are flagella found [bacteria, animals, plants]

  bacteria
• what do flagella do?

  rotate so bacteria can move