BIO common Exam Qs

• How does starch's structure relate to its function?[4]

  Large/insoluble so doesn't affect the water potential

  Branched so glucose is easily released for respiration

  Helical shape so compact

  large molecule so can't leave the cell
• Describe how organisms are grouped into a phylogenetic classification system [2]

  Hierarchy of groups with no overlaps/ smaller groups within larger groups with no overlaps

  Grouped according to evolutionary origins/relationships/history
• What is a tumour? [2]

  A mass of OR abnormal cells/tissue

  from uncontrolled cell division
• A student dissected a sheep's heart, give 3 control measures the student should use to reduce the risk associated with carrying and using a scalpel. [2] (must have 3 points for both marks)

  Cut away from body

  cut on hard surface

  Disinfect/dispose of used scalpel in tray
• What's a marking point to put down for any Q about making conclusions about phylogenetic relationships?

  Genetic variation exists between ...
• What is stroke volume and heart rate? (not an exam Q)

  stroke volume is the volume of blood pumped out of the left ventricle during one cardiac cycle

  Heart rate is the number of times the heart beats in one minute/ the number of cardiac cycles per minute
• How do you calculate cardiac output?

  Cardiac output = heart rate x stroke volume
• What makes a good control in an investigation?

  If everything else remains the same except the thing you're trying to investigate (e.g if trying to investigate whether coloured stones have an effect on the courtship behaviour of spotted fish a good control would just remove the coloured stones and keep everything else the same)
• Define the quaternary structure of a protein [1]

  More than one polypeptide
• Describe the aseptic technique a student could use when preparing a bacterial culture? [3] (Any 3)


  Wash hands with soap/disinfect surfaces

  use sterile pipette to transfer bacteria

  Remove bottle lid and flame neck of bottle

  lift lid of agar plate at an angle

  work close to upward air movement

  Use sterile spreader
• What are 3 ways in which a gene mutation can have no effect on an individual ? (these are 3 marks from a longer Q, in the longer Q the definition of gene mutation was a marking point but not needed here rn) [3]

  If the genetic code is degenerate/mutation is in intron

  does change the amino acid but doesn't affect the tertiary structure

  new allele is recessive so doesn't affect phenotype
• What are 2 ways in which a gene mutation can have a positive effect on an individual? (from longer Q) [2]

  Results in a change in the polypeptide that positively changes the properties of the protein

  may result in increased reproductive success
• Describe and explain how the structure of cellulose relates to its function. [4]

  Cellulose made up of long, unbranched chains of B-glucose

  which interact to form microfibrils

  chains of B-glucose joined together by hydrogen bonds

  which provide strength to cell walls
• Suggest and explain two further investigations that should be done before this ADC (that has been tested on mice) is tested on human breast cancer patients? [2] ANY 2 (this Q is applicable to any drug testing Q)

  Tested on other mammals to check for safety/side effects

  tested on healthy humans to check for safety/side effects

  See if repeat doses stop the tumour regrowing

  Investigate different concentrations of ADC to find suitable/safe dosage
• Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with sodium ions. Explain how. [3]

  Sodium ions actively transported from ileum cell to blood

  this maintains a diffusion gradient for sodium ions to enter with glucose from gut

  glucose enters by facilitated diffusion with sodium ions
• what's the pulmonary ventilation rate (PVR) formula?


  tidal volume x breathing rate
• Formation of an enzyme-substrate complex increases the rate of reaction. Explain how. [2]

  Reduces activation energy

  due to bending bonds/due to weakening bonds
• Lyxose binds to the enzyme. Suggest a reason for why there's a difference in rate of the reaction with and without lyxose. [3]

  the binding alters the tertiary structure of the enzyme (must say this, not conformational change)

  causes active site to change shape

  so more enzyme-substrate complexes form
• A mutation can lead to the production of a non-functioning enzyme. Explain how. [6]

  change in the base sequence of DNA

  change in the amino acid sequence/primary structure of enzyme

  change in the hydrogen/ionic/disulfide bonds

  change in the tertiary structure/shape

  change in the active site

  substrate not complementary to enzyme/no enzyme-substrate complexes form
• Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst. [3] 


  substrate binds to active sit of enzyme

  active site changes shape slightly so its complementary to the substrate

  reduces activation energy
• Describe how the structure of a protein depends on the amino acids it contains. [5]

  structure determined by position of amino acid/R group

  primary structure is sequence/order of amino acids

  secondary structure formed by hydrogen bonding between amino acids (forming alpha helix/beta pleated sheets)

  tertiary structure formed by interactions between R groups (eg disulfide bridges)

  creates the active site in enzymes

  quarternary structure contains more than 1 polypeptide chain
• describe the role of Saprobiants in the nitrogen cycle [2]

  they use enzymes to decompose DNA/urea/proteins

  producing/releasing ammonia