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
-produce 0.2,0.4,0.6,0.8 and 1% trypsin concentration solutions of same volume
-make control of 2cm3 of trypsin and 2cm3 of distilled water to zero colorimeter absorbance to zero
-to another cuvette add 2cm3 milk suspension (casein broken down by trypsin) and 2cm3 of 0.2% trypsin and start stopwatch, measure absorbance every 10 seconds for 2 minutes and calculate initial rate of reaction
-repeat for dif concens at same temp by placing in water bath and same pH using buffer and repeat three times and calculate mean initial rate of reaction
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
The effect of temp on the development of brine shrimp
-weigh 2g of salt using weigh boat and add to 100cm3 distilled water in beaker and stir with glass rod until dissolved
-place some eggs onto piece of paper and wet another piece of paper using salt water
-place wet paper face down on eggs to pick some of the eggs up and use a magnifying glass to count out 40 of the eggs and remove the rest
-then add the wet paper to the salt water and leave for three mins
-repeat four times using brine shrimp of same size and species and incubate at 5/20/30/40/50C using water bath/fridge
-after 24hrs remove the beakers and shine bright light on beaker, those that have hatched will swim towards the light and can be counted and removed
-repeat multiple times and calculate a mean number for number of brine shrimp hatched for the dif temps
Antibiotic practical
-set up sterile work area by wiping surfaces with disinfectant and set up Bunsen Burner to create convection current to kill bacteria in air
-sterilise inoculating loop by holding in Bunsen Burner and use it to inoculate Agar plate with E. coli bacteria and sterilise loop after using
-soak paper discs in dif types of antibiotic and add negative control by soaking disc in distilled water and add discs to Agar plate using sterilised forceps
-lightly tape lid onto Petri dish and invert dish in incubator and incubate for 48hrs at 25C
-calculate size of zones of inhibition around each antibiotic disc by measuring radius using ruler, larger the zone the more effective the antibiotic
How to calculate Q10
Divide rate at T + 10C by rate at T degrees
How to find initial rate of reaction
Draw tangent at 0 seconds
