general paper 1 revision

• Biology – Triple Science Paper 1 Revision Mrs Smith April 2024
• Video links


  • (Microscopy)
  • (Microbiology - culturing Microorganisms)
  • (Osmosis)
  • (Food Tests)
  • (Enzyme Action)
  • (Photosynthesis)
• Students should have a basic understanding of the following biological principles and be able to apply them in either paper

  • The structure and functioning of cells and how they divide by mitosis and meiosis
  • That variation occurs when gametes fuse at fertilisation
  • The two essential reactions for life on Earth: photosynthesis and respiration
  • Metabolism is the sum of all the reactions happening in a cell or organism, in which molecules are made or broken down
  • All molecules are recycled between the living world and the environment to sustain life
• A quick blast through cell biology

  • Cell structure
  • RP: Microscopy
  • Specialised cells (differentiation)
  • Mitosis
  • Binary fission
  • Culturing microorganisms
  • Stem cells
  • RP: Diffusion, osmosis active transport
  • Exchange surfaces (surface area to volume ratio)
• Cells, specialised cells


  • Organs – Heat, lungs, Respiration and gas exchange
  • Pathogens and disease – communicable and non-communicable
  • Digestion – system, food tests, enzyme
  • PLANTS
  • BACTERIA
  • ANIMALS
  • FUNGI /PROTISTA
  • Osmosis, Diffusion, Active Transport
  • Specialised cells – palisade, xylem, phloem
  • Transpiration – stomata, potometers
  • Photosynthesis – rate, factors affecting,
  • How plants use glucose
  • Medicines from plants
  • Pathogens and disease – salmonella, gonorrhoea
  • Vaccines and preventing disease spread
• SKILLS


  • Magnification = image / real size
  • Surface area to volume area ratios
  • Pathogens and disease
  • Malaria (mosquitos)
  • Rose black spot (leaves)
• Required Practicals

  • Using a light microscopes
  • Osmosis – concentration / mass of plants
  • Microbiology – growth of microorganisms
  • Food Tests to identify food groups
  • Enzymes – effect of pH on rate of reaction
  • Light intensity on rate of photosynthesis
• RP 1 : How do we find the overall magnification of a light microscope?

  1. Eyepiece Magnification

  2. Objective Magnification

  3. Overall Magnification
• Magnification


  image size / real size
• Resolution


  the ability to distinguish between 2 points – a sharper image is seen
• Light microscope


  • Can see individual cells and large subcellular structures
  • Coloured images seen
  • Living organisms seen
• Electron microscope


  • Can see small images like chloroplasts, mitochondria
  • They have a higher resolution
  • Only black and white images
  • 3D images
• Required Practical – Biology 1 – Using a light microscope

  1. Use a stain to make things visble

  2. Get the specimen as flat and thin as possible

  3. Start on the smallest lens, focus, then move up a lens

  4. a ruler, or eyepiece scale can be used to measure size
• Magnification


  image size / actual object size
• • 1mm = 1000um
  • 1um = 1000nm
• We can see the nucleus and cell wall but not the mitochondria (they're far too small and not stained)
• We can see smaller parts of cells using an electron microscope (it has much higher resolution and magnification)
• Both types of cell have

  • Cell wall
  • Cell Membrane
  • Cytoplasm
  • Nucleus
• Only plant cells have

  • Large Vacuole
  • Chloroplasts
• Specialised cells


  • Root hair cell
  • Sperm cell
  • Fat cell
  • Palisade cell
  • Nerve cell
  • Red blood cell
• Diffusion


  The movement of particles from an area where they are at a high concentration to an area where they are at a lower concentration , down concentration gradient e.g. oxygen, carbon dioxide , glucose move in and out of cells this way
• Osmosis


  The diffusion of water only through a partially permeable membrane from a dilute to a concentrated solution
• Active transport


  When substances are absorbed from a lower concentration to a higher concentration against the concentration gradient
• RP 2 : Culturing Microorganisms (antiseptics and antibiotics)

  1. Agar plates – agar gel with nutrients – growth medium

  2. Antibiotics – kill bacteria

  3. Antiseptics – kill pathogens

  4. Zone of inhibition – area around the disc where no bacteria have grown

  5. Incubation

  6. Innoculating loop – small wire loop to transfer cultures

  7. Sterilisation

  8. Aseptic technique

  9. Binary fission – bacteria replicate every 20 mins by binary fission
• Preparing the agar plates of a colony of bacteria


  1. Glass Petri dishes and agar gel must be sterilised before use in an autoclave, or pre-sterilised plastic Petri dishes can be bought

  2. Pour the sterile agar plates and allow to set fully

  3. Sterilise the inoculating loop, by heating it in the Bunsen burner flame

  4. Dip the inoculation loop into the microorganism solution and make streaks on the surface of the agar plate

  5. Replace the lid as soon as possible, secure with tape. Label and invert the plate, and store upside down

  6. Incubate at a maximum temperature of 25°C in schools and colleges
• Zone of inhibition


  Area around the disc where no bacteria have grown
• RP 3 – Biology 1 – Investigating Osmosis


  1. Measure the length (or mass) of the potato cylinders before and after

  2. Control variables

  3. Accuracy of measurements – why should you remove excess water with paper towel before weighing

  4. Use a graph of results to find the concentration inside the potato cells

  5. Why can the water, but not the sugar/salt move through the membrane?
• Osmosis


  The movement of water from an area with high concentration OF WATER, to an area with lower concentration OF WATER
• Solute


  Something that dissolves in water
• Results


  • High concentration of sugar in solution = water moves out of potato cells into the solution. Potato gets smaller.
  • Low concentration of sugar in solution = water moves into the potato cells from the solution. Potato gets bigger.
  • If no water goes in or out of the potato overall and it doesn't change mass, then the solution is exactly the same concentration as inside the potato
• Rate of change


  change in mass / 24 (hr)
• Percentage change in mass


  (final mass - original mass) / original mass x 100
• The concentration of sucrose inside the potato is 0.3 mol/dm 3 As there is no net movement of water
• Surface area to volume ratio calculations

  1. Volume: length x width x height

  2. Area : length x width

  3. Ratio: Surface area : volume ratio
• • Ratio of 6:1 has a surface area 6 times its volume
  • Ratio of 2: 1 has a surface area twice its volume
• Describe mitosis (Cell cloning)

  1. DNA Replicate

  2. Chromosomes line up/ attach to either side

  3. Chromosomes separate

  4. Cell divides

  5. 2 identical daughter cells
• Cell organisation


  • Organelle
  • cell
  • tissue
  • organ
  • organ system
  • organism
• Food Food Type


  • Protein
  • Starch
  • Lipid (fat)
  • Sugar (glucose)
• Test Solution


  • Biuret
  • Iodine
  • Alcohol
  • Benedicts
• Positive Result


  • Blue to purple
  • Brown to Blue/black
  • Turns cloudy
  • Blue to Orange