topic 1.2: practical skills in practical endorsement Flashcards
calibrating eyepiece graticule
set up microscope to required mag, line up stage and eyepiece graticules, count number of divisions on EG equivalent to SG, calculate length of one EG division
using light microscope
clip slide onto stage, select lowest objective lens, use coarse adjustment knob to move OJ, use fine adjustment until clear image appears
scientific drawings
no shading, half page, horizontal label lines, no hairy lines, scale, pencil
health and safety in dissection
take care using sharp instruments, non-latex gloves to protect from harmful chemicals, goggles, apron, dispose of waste responsibly
random sampling
random coords
+prevents biased data
-not all areas sampled equally (inaccurate)
-small pop species missed
stratified sampling
divide habitat into groups, mutually exclusive and collectively exhaustive
+all areas sampled
+small pops counted
-over rep of some areas
opportunistic sampling
areas chosen either through prior knowledge or interest
+easy and quick
+more data
-over rep
-inaccurate estimate of biodiversity
systematic sampling
taken at set distances
+view change in biod
-may miss species
how would you measure mass
how would you measure time
stopwatch
how would you measure volume
measuring cylinders or syringes
how would you measure temperature
thermometer
how would you measure length
ruler
how would you measure ph
serial dilution
set up boiling tubes, add start solution, add half to next tube with half water, repeat. halves concentration each time
colorimeter
-switch on and leave to stabilise
-select filter (eg red for benedicts)
-set to 0 using cuvette of distilled water
-ensure sides are clean and solution has no bubbles
-fill cuvette 3/4 with solution
-higher transmission = paler solution
potometer
-cut shoot underwater (prevents air entering) at a slant
-assemble in water and insert shoot
-keep capillary tube submerged
-keep watertight using petroleum jelly
-dry leaves
-shut tap
-remove capillary from water until 1 bubble forms, put back in water
-record start position
-record position at reg intervals
-calc transpiration rate
limitations of potometer
not all water used for transpiration, some used to maintain turgidity
some used in photosynthesis
plant dies after cutting off root- may take up less water
chromatography: stationary phase
tlc plate or chromatography paper (cellulose)
chromatography: mobile phase
solvent
chromatography: chlorophyll pigment
-grind leaves in pestle and mortar with solvent
-transfer to test tube
-draw line on tlc plate with pencil 2cm from bottom
-use capillary tube to place dot of pigment solution in middle of line
-allow to dry then add another until concentrated
-add solvent to beaker less than 2cm depth
-place plate in beaker with bottom touching solvent
-place watch glass over beaker to stop evaporation
-mark locations of pigments
-calc rf value
electrophoresis
-pour agarose gel into tray and leave to solidify
-add buffer solution
-add loading dye and dna to wells
-apply current from negative end
-smaller fragments move faster to pos electrode
-run for 30mins
aseptic techniques
-wash hands and disinfect area
-bunsen burner nearby to sterilise air and prevent microbes settling
-pass neck of tubes over bunsen
-open petri dishes minimally
-sterilise equipment eg inoculating loop through flame
biuret test
protein
-add sodium hydroxide, add copper sulphate
blue -> purple
