biology core practicals

microscope practical

1.place slide on stage and secure with stage clips 2.select the lowest power objective lens 3. turn course focusing dial until slide is almost touching objective lens 4.look down eyepiece and turn course focus until image becomes clear 5.turn fine focus dial util image becomes focused

culturing microorganisms practical

1.sterlise all equipment 2.sterlise inoculating loop by Bunsen burner 3. open agar plate by a Bunsen burner to kill bacteria in air 4.use loop to spread bacteria over plate 5. place sterile paper discs containing antibiotic onto the plate 6.incubate plate at 25

effect of osmosis on plant tissue practical

1.peel potato 2.use a cork borer to produce 3 cylinders of potato 3.use scalpal to trim to same length 4.meausre length of each cyclinder with ruler. Measure mass with a balance 5.put each cylinder in a test tube 6.add 10cm³ of 0.5 molar sugar solution in first test tube 7.add 10cm³ of 0.25 molar sugar solution in second tube 8.add 10cm³ of distilled water into third test tube 9.leave tubes overnight 9.remove cylinders and roll over a paper towel 10. measure length and mass again

potato osmosis results

1. in the 0.5 sugar solution the potato loses the most mass 2. in the 0.25 sugar solution the potato gains mass 3.the distilled water potato gained the most mass

what does benendicts solutions test for

reducing sugars

what is the iodine test for

starch

what is the biuret test for

proteins

what is the emulsion test for

lipids

how to complete the iodine test

1. add food sample to test tube 2.add a few drops of iodine 3.record colour change

   If the colour stays orange no starch is present. If the colour changes to blue/black, starch is present

how to complete the emulsion food test

1. add food sample to test tube 2. add a few drops of ethanol and distilled water 3.shake solution to mix

   If lipids are not present the solution will stay colourless. If lipids are present the solution will produce a cloudy emulsion.

how to complete the biuret test

1. Add food sample 2.add a few drops biuret solution 3.shake to mix in

   If solution stays blue no proteins are present. If solution goes lilac/purple then proteins are present.

how to complete the benedicts solution test

1. add food sample to test tube 2. add benedicts solution to tube 3.put in water at 80 degrees for 5 mins

   If solution stays blue then reducing sugars are not present. If solution goes green-brick red then reducing sugars are present.

test on affect of ph on amylase

1. place on drop of idoine into each well of a spotting tile 2. in 1 test tube put 2cm³ of starch solution. In another put 2cm³ of amylase solution. In another test tube put 2cm³ of a PH 5 buffer solution. 3. Put all three test tubes in a water bath at 30 degrees for 10 mins. 4. Mix all solutions into one test tube and immediatley return to waterbath. wait 30 seconds. 5.use a pipette to drop one drop of the water bath solution into a well of iodine. 6. take a sample every 30 secs until iodine has no colour change. 7. Repeat reaction with ph 6,7,8

photosynthesis practical

1. take a boiling tube and place it 10cm³ away from a LED light source 2. put sodium hydrogen carbonate solution into test tube 3.put pondweed into boiling tube and leave for 5 mins to acclimatise 4.start a stopwatch and count number of bubbles produced in one minute. 5. repeat 2 more times and calculate a mean 6. repeat steps for 20,30,40cm

   -can improve method by placing pondweed under a funnel and catching bubbles in a measuring cylinder filled with water

respiration practical

1. put sodalime granules into a test tube with cotton wool on top. 2.weigh out a select amount of maggots and place them in the boiling tube. 3. place a capillary tube and bung ontop of boiling tube 4. set up a control tube without organisms 5. put both test tubes in a water bath of 34 degrees. 6. allow to aclimamtice for 5 mins 7.after 5 mins put coloured liquid into ends of capillary tubes. 8.mark position of coloured liquid in tubes and time for 5 mins 9. after 5 mins measure coloured liquid position again. calculate change in distance 10. repeat with different temps but same number of organisms

field investigation practical

1.find area of area being sampled 2. split up into 1 m² squares 3.use random number generator to remove bias of where to investigate 4.count number of organisms in the quadrat 5. to estimate population times mean number or organism by area