paper 1 practicals Flashcards
1
Q
what is the method of the microscopy practical?
explain both steps preparing the slide and using the microscope
A
- peel of epidermal layer of onion w forceps
- mount onto microspoe slide w drop of water [use pippete]
- add a drop of iodine to stain the cells
- place cover slip on [do one edge then lower slowly = precvents bubbles]
- place slide on microscope stage
-select lowest objective lens - use the coarse adjustment knob to move the stage up
- look through eye piece adjust the coarse focus [move away until image is focused]
- then adjsut the fine adjustment knob = to get a clear image
- more magnification = swap to a higher powered lens
- make a labelled drawin. write down magnification
2
Q
what are the saftey precautions of the microsopy pratical
A
- wear safety goggles [iodine soultion]
3
Q
explain the effedct antibiotics has on bacterial growth practical:
A
- spray your bench with disinfectant then wipe dry w paper towels
- place paper disks soaked in different types of antbiotics & 1 with no antibiotic = control on an agar plate that has had an even coating of bacteria
[lift the lid slightly and place disks w forceps] - tape the lid onto agar [slighly loose to allow oxygen to reach bacteria]
- place agar plate in incubator for 45 hours at 25degrees
- take measurements of diameter [dont remove lid]
- larger the inhibition zone = more effective antibiotic
4
Q
for the antibiotic practical what needs to be done to growth of other microorganisms?
[give 4]
A
- sterlise equipment
- tape lightly to prevent microorganisms in the air getting in
- store upside down = to stop drops of condensation falling onto the agar surface
- only open the lid slightly/on an angle
5
Q
safty precautions of antibiotics practical
A
- wash hands before and after jandling bacteria
- wear saftey goggles [disinfectant]
6
Q
explain the osmosis practical
A
- cut a patatoe into 5 identical cylinders
- prepare 5 diff beaker w diff conc on sugar solution [1 be pure water, one be very high e.g 1 mol/dm3, some others inbetween]
- measure the mass of the cylinders
- place into beaker & leave for 24hours
- take them out, dry [blot w paper towels] & measure mass again
- calcualte % change
- repeat for a fair test
- plot on graph
7
Q
potential errors for osmosis practical?
A
- not fullly dried
- water may of evaportaed from beakers [changing conc of sugar]
8
Q
safety measures for osmosis practical?
A
- be careful when using sharp knife
9
Q
explain the enzymes practical?
what would you do next time?
A
- add a drop of iodine into every well of the spotting tile
- place a bunsen on a heat proof matt etc place a beaker of water on tripod and heat until 35 degrees
[keep temp constant measure w thermometre] - use a syringe to add 1cm3 of amylase & 1cm3 of a buffer solution [PH of 5] into boiling tube
- place into beaker and wait 5 mins[so they can reach same temp]
- use a dif syringe to add 5cm3 of starch solution to the boi;ing tube mix contents and start stop watch
- use continuos sampiimg use a pippete and every 30s take a frsh sample from the boiling tube and drop into new well
- when no colour change = starch is all broken down
- repeat w differnet buffer solution = diiff PH values
10
Q
safety precautions for ezyme practical?
A
- be carfeul when using hot water
- bunsen = tie long hair back
- wear goggles
11
Q
explain the photosynthesis practical:
A
- place a clamp w boiling tube w pondweed & water 10cm away from the light source
- leave for 5 minutes = for pondweed to photosynthesis
- start stopwatch and count the number of bubbles produced in 1 min
- repeat 3x and take a mean
- repeat these steps w diff distances [20,30,40,50etc]
-plot rate of photosynthesis against light intensity on a graph
12
Q
what is the equation for light intensity
A
1/distance^2
13
Q
safety precautions for photosynthesis practical
A
- lamp may get hot
- keep water away from power sources
14
Q
A
