Practicals Flashcards
Daphnia heart rate
-dilute caffeine solutions with distilled water to product dif concens(at least 5)
-place cotton wool(to restrict movement) on cavity slide and add one large daphnia
-use filter paper to absorb water around flea
-use dropping pipettes to ass few drops of distilled water to slide, do not use coverslip to prevent conditions becoming anoxic
-place slide on microscope, use stop clock to time minute and record number of heart beats
-repeat using dif concens of caffeine solution, use same size and species and time left to acclimatise
Vitamin C concentration
-transfer 1cm3 DCPIP to conical flask with pipette and fill burette with vitamin C solution
-add vitamin C solution to conical flask while swirling until DCPIP decolourises, record volume
-repeat twice and calculate mean
-repeat with fruit juices and calculate vitamin C concen as proportion of vitamin c solution, using same volume of DCPIP
Membrane permeability beetroot
-cut beetroot into 8 cylinders of same length using cork borer and dry
-place each in 10ml of distilled water and place each test tube in water bath at range of temps between 0 and 70C
-leave samples for 15 minutes and record exact temp of water bath using thermometer
-remove test tubes from water baths and take sample of liquid from each using pipette, transfer to cuvettes
-set colorimeter to blue filter and zero using cuvette filled with distilled water
-measure absorbance for each, use same volume water and length of beetroot sample
Effect of enzyme and substrate concentration on initial rate of reaction
-cut 10 discs 0.2mm thick of potato and place in boiling tube with 5cm3 of chilledbuffer solution
-add 5cm3 hydrogen peroxide to potato discs and immediately place bung and delivery tube firmly into boiling tube, place other end of delivery tube under collecting tube filled with water
-start stop clock when first bubble of oxygen enters collecting tube from delivery tube and record volume every 30 seconds for 5 minutes shaking boiling time throughout
-plot graph for time against volume of gas produced to calculate initial ror
-repeat 3x to calculate mean and repeat for dif number of discs using same volume and concen of hydrogen peroxide and same thickness of potato samples
Observing stages of mitosis
-cut 5mm sample of root tip using scalpel
-transfer to test tube of HCl and leave for five mins(breaks down cell wall), transfer to watch glass containing cold distilled water and leave for 5 mins and dry
-place root tips on microscope slide and mascerate with need to spread cells out (makes chromosomes visible)
-add drop of to toluidine blue to slide and leave for two mins
-lower cover slip over slide, make sure no air bubbles(distort image), doesn’t slide sideways(could damage the chrs) and gently squash slide
-place on microscope and adjust so in focus (coarse to move slide, fine to re-adjust focus until clear)
-count number of cells undergoing mitosis in view, divide by total no cells visible to get mitotic index
Structures of stem
-calibrate eyepiece graticule by lining up divisions of stage micrometer with divisions of eyepiece graticule
-cut transverse sections of stem on white tile using razor, wet to reduce friction, cut as thinly as possible
-place on microscope slide and add few drops of toluidine blue and lower cover slip carefully
-place under microscope and use lowest power objective lens
-observe and draw stem and measure stem and vascular bundle diameter using calibrated eyepiece graticule
Plant mineral deficiencies
-use measuring cylinder to fill test tubes with 5cm3 of dif nutrient solutions and one without any and one with all as controls
-add cotton wool and seedlings of same size and species to each
-cover top with tinfoil and poke three holes
-place on test tube rack and leave for week on same windowsill
-record change in height of each holding vertical with ruler and record observations eg leaves and colour
Tensile strength of plant fibres
-use forceps to separate fibres and cut 10cm sample using scalpel
-attach each end to clamp stands and attach increasing masses at regular intervals until fibre breaks
-multiply mass by cross sectional area to get tensile strength
-repeats for dif lengths of same plant stored in same conditions of same thickness
Antimicrobial properties of plants
-carry out aseptic technique
-crush set mass of garlic with methylated spirit
-use sterile pipette to transfer plant extract to paper disc and place onto Petri dish innoculated with bacteria
-lightly tape lid on (prevents growth of anaerobic bacteria) and incubate 25C for 24hrs
-sterilise equipment used to handle bacteria and disinfect work surfaces
-measure diameter of inhibition zone for plant and work out area
-repeat for mint using same type of bacteria and same time incubated, repeat multiple times and calculate mean
Ecology of habitat
-choose site where there is obvious gradient in abiotic variable and place transect down, select species that changes in abundance along gradient
-place quadrant every 2m along gradient with bottom left corner on mark each time
-measure abundance of chosen species in quadrant each time and measure light intensity using photometer at each
Hill reaction
-remove same mass of leaf sample and grind using pestle and mortar and add set volume of chilled isolation mixture(cold and buffered to stop enzyme denaturation,sucrose to prevent osmotic loss of water from chloroplasts)
-filter using muslin cloth
-transfer to centrifuge tubes and centrifuge at high speed for 10mins
-separate pellet and add to chilled isolation mixture
-set colorimeter to red filter and zero using cuvette of only chloroplast extract
-add set volume of DCPIP to test tube 30cm from light source and immediately take sample and add to cuvette and measure absorbance
-take sample and measure absorbance every 2mins for 10mins and repeat for 60,90,120 cm
-repeat 3x and calculate mean for absorbance for each distance
