B1

• 1.1- explain how the sub- cellular structures of eukaryotic and prokaryotic cells are related to their functions- animal cell parts (4)

  nucleus, cell membrane, mitochondria, ribosomes
• explain how the sub- cellular structures of eukaryotic (has a nucleus) and prokaryotic cells are related to their functions- plant cells (7)


  nucleus, cell membrane, cell wall, chloroplasts, mitochondria, vacuole, ribosomes
• explain how the sub- cellular structures of eukaryotic and prokaryotic cells are related to their functions- bacteria (5)

  chromosomal DNA, plasmid DNA, cell membrane, ribosomes, flagella
• nucleus


  controls the cell and its activities. inside are chromosomes containing DNA
• cell membrane


  controls what enters and leaves the cell and separates one cell from another
• Mitochondria


  aerobic respiration occurs
• ribosomes


  in cytoplasm, makes proteins for a cell
• cell wall (outer side)


  supports and protects the cell
• chloroplasts


  contain chlorophyll, which traps energy transferred from the sun. the energy is used for photosynthesis
• vacuole


  stores cell sap and helps to keep the cell firm and rigid
• Chromosonal DNA


  controls most of the cell's activities
• plasmid DNA


  controls a few of the cell's activities
• flexible cell wall and slime coat


  for support and protection
• Fagella


  spins round like a propeller, so the bacteria can move
• 1.3- Explain how changes in microscope technology, including electron microscopy, have enabled us to see cell structures and organelles with more clarity and detail than in the past and increased our understanding of the role of sub-cellular structures- light microscope

  the light microscope was invented at the end of the 16th century and was used by Robert Hooke to discover cells in 1665. it had a magnification of x30 and resolution of 0.002. It was not very powerful.
• how have light microscopes developed today

  development of stains (iodine solution) for specimens, better lenses and light sources
• electron microscope


  The electron microscope was invented in the 1930s. Instead of light they passed beams of electrons through a specimen to build up an image. They had better detail and clarity because the magnification was up to x2000000 and resolution down to 0.0000002mm
• how do you work out a microscope's magnification and which lenses

  multiply the magnifications of the objective and eyepiece lens
• how do you focus a microscope

  turn the fine focusing knob, increase the magnification
• resolution


  smallest distance between two points that can still be seen as two points
• 1.5- demonstrate an understanding of the relationship between quantitative units in relation to cells

  1 metre (m)= 1000 millimetres (mm)
• mm to μm conversion

  1 millimetre (mm) = 1000 micrometres (um)
• μm to nm conversion

  1 micrometer (um) = 1000 nano metres (nm)
• nm-pm conversion


  1 nano metre (nm)= 1000 pico metres (pm)
• 1.6 Core Practical: Investigate biological specimens using microscopes, including magnification calculations and labelled scientific drawings from observation


  add a drop of water or stain to microscope slide

  
  

  place specimen on this

  
  

  use a toothpick to slowly lower coverslip onto the specimen (means slide is less likely to contain air bubbles)

  
  

  coverslip keeps the specimen flat, holds it in place and stops it from drying out
• 1.7- explain the mechanism of enzyme action including the active site


  the active site is where the substrate of the enzyme fits at the start of a reaction. the substrate and enzyme active site have complementary shapes
• 1.7- explain the mechanism of enzyme action including enzyme specificity

  Different substrate have different 3D shapes, and different enzymes have different active site shapes. This explains why every enzyme can only work with specific substrates that fit the active site
• 1.8- explain how enzymes can be denatured due to changes in the shape of the active site


  If the shape of the active site changes too much, the substrate will no longer fit in. The enzyme will no longer be able to catalyse a reaction, so the enzyme is denatured.
• 1.9- explain the effects of temperature, substrate concentration and pH on enzyme activity- temperature increasing


  as the temperature increases, molecules move faster. higher speeds increase the chance of substrate molecules bumping into enzyme molecules and slotting into the active site.
• 1.9- temperature too high


  However, when the temperature gets too high, the shape of the enzyme molecule starts to change (denature) . the amount of change increases as the temperature increases. so it becomes more difficult for a substrate molecule to fit into the active site
• 1,9- optimum temperature


  temperature at which an enzyme works fastest
• 1.9- substrate concentration


  at low concentrations, many enzyme molecules have empty active sites so the rate of reaction is slow. At high concentrations, most enzyme active sites contain substrate molecules, and the rate of reaction is as fast as it can be
• 1.9- pH


  the optimum pH is 7 (neutral). At pHs above and below the optimum, the shape of the active site is affected (denatured) and so the enzyme does not work as well.
• 1.10- core practical: investigate the effect of pH on enzyme activity


  heat water to 40 degrees. Place one drop of iodine solution into each dimple tile. Measure 2cm cubed of amylase solution into a tube. add 1mc cubed of a solution with a particular pH into the tube. Add 2cm cubed of starch solution to the tube and place it carefully into the water bath. start stop clock and stir. Every 20s, take a small amount of mixture and place one drop into a fresh iodine solution. stop testing when iodine solution stops changing colour. repeat with different pHs
• how do you know when the reaction is complete

  it starts at blue/ black, goes to brown, and a yellow/ orange colour indicates that the reaction is complete
• 1.11- demonstrate an understanding of rate calculations for enzyme activity


  amount broken down/ product formed divided by time
• 1.12- explain the importance of enzymes as biological catalysts in the synthesis of carbohydrates, proteins and lipids and their breakdown into sugars, amino acids and fatty acids and glycerol- importance


  digestive enzymes turn the large molecules in our food into the smaller subunits they are made of. the digested molecules are then small enough to be absorbed by the small intestine
• What is synthesis?


  Building larger molecules from smaller subunits
• what are complex carbohydrates and proteins

  polymers as they are made up of many similar small molecules, monomers, in a chain, to make a polymer
• What does a protein molecule synthesise into?

  synthesises into amino acids