Final checks:

  • Adaptations of chloroplasts: ATP synthase in thylakoid membrane is selectively permeable allowing to maintain concentration of H+


  • Required practical of Photosynthesis key points:

The theory behind:

  • In the light dependent reaction, when electrons are released, DCPIP takes place of NADP and accepts the electrons, colour change from blue to colourless, when reduced

  • CO2 conc → Fixed volume of sodium hydrogen carbonate solution



  • At some point lactate is oxidised back to pyruvate or further oxidised to release energy or converted to glycogen

  • Oxaloacetate is 4C, citrate is 6C

  • TTA PPK => Triglycerides, triose phosphate and acetyl-coA AND Proteins are deaminated and hydrolysed to pyruvette and 4C or 6C in the krebs cycle


  • Biomass: The total mass of living material is a particular area at a given time

  • N = I - (R+ F)

  • Don’t forget to say that heart is myogenic

  • Osmoreceptors detect the water concentration, and send to pituitaty gland

  • Myosin head binds to the actin binding site, the release of ADP and Pi causes a powerstroke, when new ATP molecule binds to myosin head the myosin head dettaches, and when ATP is hydrolysed to ADP and Pi then the myosin head reverts back to origional position.

  • In the glomerulus to bowmans capsule: the endothelium of glomerulus, basement membrane, and podocytes.

  • Multiple alleles: Having more than 2 alleles for a gene


  • remember these key points for hardy-weinburg equation:

    • No mutation so no new allele formed

    • No migration or immigation

    • Large population

    • Mating is random

    • All alleles have equal chance to be passed down to offspring


  • Epigenetics: Heritable changes to the gene function, without changes in DNA base sequence

  • In Vitro => inside glass // In vivo => Inside organism


How to sequence a gene?

  • Restriction mapping

  • To form many DNA fragements use many different restriction endonucleases that are specific at different recognition sites

  • Then use PCR to amplyfy the number of DNA strands

  • Then use gel eletrophoresis to separate and identify each strand

  • Then compare them with a ladder of known DNA fragements

  • Or scan using a computer and let the computer interpret the results


  • VNTRS → Variable number tandem repeats => they are the non-coding regions.



From past paper question:

  • Biomass = mass per area per unit of time e.g. Kg/meter squared per year

  • Advantage of conversion of lactate into pyruvate, so can be used for aerobic respiration, to reduce build-up of toxic material, to recover from muscle fatigue

  • So, next to tree which undergoes photosynthesis, produces sugars that are moved to the roots of the plant, the sugars are used in aerobic respiration + time delay for sugars to be transported to the root of the plant

  • Artificial fertilisers, are more soluble and less energy required to breakdown the organic matter.

  • Grow plants with nitrogen fixing organism to increase concentration of nitrates in soil.

  • Stoke volume is the volume of blood removed pumped from the ventricle per heart beat

  • Act as a marker gene.

  • The negative impacts of plasmid containing plant interbreeding with other organisms, will disrupt the food chains, where the producer is this particular plant, since the insects that feed on will have no food source, and this will effect other trophic levels.

  • Genetically modifying plants, ensures same desired characteristics.

  • DNA primers are added: to prevent the DNA strands from anneling (keep the strands apart)/ allow attachment for enzymes and nucleotides/ to mark the beginning and end of the DNA strands// to initiate replication

  • How does DNA fingerprinting take place?

    • DNA extracted from sample

    • DNA cut using restriction endonuclease to form DNA fragements

    • DNA fragements separated using gel eletrophoresis

    • DNA put in the reaction wells and electric current (voltage) passed through

    • Separation occurs due to length

    • Transfer the results into membrane

    • Add DNA probes complementary to VNTRs so they are visible

  • When why is radioactive or fluorescent probe used?

    • The DNA is invisible on the gel

    • So, allows detection

  • Common question: why is fluroescent marker used? => not all eggs will successfully take up plasmid, silkworms that have taken up gene will glow only

  • Predator-prey graph:

    • Prey increases due to less predators

    • As prey increases = more food for predators, so predators increases

    • Increased predators decreases prey

    • Decreased prey = less food for predators, so predators decreases

    • ALSO INCLUDE THE TIME INTERVAL FOR THE CYCLES (time taken for prey/predator to increase in number then decrease in number)