core practicals

• CP5 – Mitosis microscopy

  1. Use root tips of plant species of same age/source (garlic)

  2. Add hydrochloric acid to break down middle lamellae to allow to produce a thin layer of cells

  3. Add toluidine blue to make the chromosome visible to identify stages of mitosis

  4. Squash under a coverslip on a microscope slide

  5. Control environmental variable (temperature, humidity)
• Mitotic index

  Number of cells undergoing mitosis/total number of cells in the field of view
• CP6 – Xylem and phloem microscopy

  1. Use plant species of same age/source (rhubarb)

  2. Use forceps to pick out vascular bundles

  3. Use mounted needle to tease apart the vascular bundles apart

  4. Add methylene blue to stain the xylem and phloem

  5. Mount under a coverslip on a microscope slide

  6. Control environmental variable (temperature, humidity)
• CP7 – Mineral ions deficiency

  1. Use plant species of same age/source (mung beans)

  2. Control environmental variable (temperature, humidity)

  3. A range of conditions – type of mineral ions or concentration of mineral ion

  4. Grown for the same period of time – 2 weeks

  5. Relevant method to measure growth – height/length of shoot or root/ number of leaves/ mass

  6. Repeats to calculate mean
• CP8 – Tensile strength


  1. Fibre variable taken into account: height or length or age or source or species

  2. Control environmental variable (temperature, humidity)

  3. Attach fibres to clamp stands

  4. Add masses until fibre breaks

  5. Calculate tensile strength by dividing force to cross-sectional area

  6. Repeat and calculate mean
• CP9 – Antibacterial property

  1. Extract made from plant (mint or garlic)

  2. Extract placed on paper disc on the agar plate with bacteria

  3. Control used – paper disc plus solvent only

  4. Incubate at temperature between 20 and 30 degrees overnight

  5. Calculate the area of the zone of inhibition (the clear area around extract)

  6. Repeat and calculate mean
• CP10- Ecology of a habitat

  1. use of quadrats for sampling
  2. determine co-ordinates for random sampling e.g., through random generator
  3. record percentage cover of species researched
  4. several quadrats measured and mean calculated
• CP3. Steps to improve the validity of investigating the effect of detergent on membrane permeability of beetroot

  1. Use beetroot of the same age/source to ensure constant concentration of betalain inside cells

  2. Use beetroot cubes of same size as surface area to volume ratio can affect rate of diffusion

  3. Control temperature as an increase in temperature will increase membrane permeability/rate of diffusion

  4. Repeat at each detergent concentration to calculate mean
• Experiment to investigate the effect of enzyme concentration on the initial rate of reaction

  1. Use potatoes of same age/source, potatoes discs of same size

  2. Control pH, temperature as they can affect rate of reaction

  3. Use different number of discs for different enzyme (catalase) concentrations

  4. Add same concentration and volume of hydrogen peroxide (substrate), then mix

  5. Record volume of oxygen released in an inverted water-filled measuring cylinder

  6. Plot and calculate initial rate of reaction from the linear part of graph of volume of oxygen against time

  7. Repeat at each enzyme concentration to calculate mean
• CP1- heart rate in daphnia

  1. dilute caffeine solution with distilled water
  2. daphnia of similar size, source
  3. place cotton wool to restrict movement on cavity slide
  4. do not use coverslip