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 in 30C water bath(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 needle 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 and measure initial height
-cover tinfoil and poke three holes
-place in water bath and leave for week, monitor change in height each day
-record change in height of each holding vertical with ruler and record observations eg leaves and colour and development of diseases, repeat for the same nutrient solutions and calculate mean and sd for height change for each
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
-divide force 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 quadrat 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
What breaks down hydrogen peroxide and into what
Catalase, into oxygen
What breaks down starch and how to see colour change and what is it
Amylase, from blue-black to colourless when starch not present using iodine
Snail habituation
-dampen cotton bud in distilled water
-touch snail between its eye buds and use stop clock to measure time taken for snail to fully re-emerge from its shell
-repeat for ten touches
-repeat for dif snail of same size and species and calculate mean time for each touch
Maggot rate of respiration practical
- Assemble respirometer using boiling tube with set mass of soda lime (to absorb CO2) under mesh
-place 5g of maggot into the boiling tube of the same species and size
-introduce a drop of marker fluid into the pipette
-mark the starting position of the fluid on the pipette using a permanent marker
-add the pipette and bung to the booking tube and immediately start stop clock
-measure with a ruler how far the fluid travels every minute for five minutes
-convert the distance the fluid travelled into volume of oxygen produced by measuring diameter of tube and calculating area
-repeat for 10, 15, 20 and 25g of maggots
-collect data during initial rate of reaction before factor other than number of maggots becomes limiting
Measuring effect of exercise on breathing rate
-person at rest breathes into spirometer for one minute and record results
-will then exercise for two minutes while spirometer chamber is refilled with oxygen
-after they stop exercising they will immediately breathe into the spirometer for one minute and record results
-person will take a rest for two minutes to allow breathing rate to return to normal and then do exercise for two minutes and breathe into spirometer for one minute
-repeat for four more exercises of different intensities with same person and repeat twice more to calculate mean and standard deviation for breathing rate for each exercise and compare recordings taken before and after exercise
How to test for starch concen
Iodine starch test to measure reducing sugars
