P1 biology required practicals

what’s the method of the microscopy practical

1. place thin layer of onion epidermis flat on a slide

2. add a drop of iodine (highlights nucleus)

3. place coverslip at an angle to avoid air bubbles

4. start on lowest magnification

5. use course focus and then fine focus

6. then draw your cells

method of microbiology (effects of antibiotics on bacteria)

1. sterilise equipment with bonsen burner

2. pour agar into petri dish

3. spread bacteria using sterile loop

4. add antibiotic disks evenly spaced out

5. place lid on but not fully sealed

6. measure diameter of inhibition zone

osmosis practical method

1. cut potato cylinders with cork borer

2. measure mass of each one

3. add 10cm3 sugar solution to tube 1

4. repeat but with different concentrations

5. add one potato to each tube, leave overnight

6. remove them and pat dry then

7. re-measure the mass and work out the change

food tests (starch,proteins and reducing sugars)

Method for all three

1. put sampled food into test tubes

2. add few drops of …

3. if the thing is present a colour change will occur

what to add to the different food tests and what is the colour change/what is formed

STARCH= add iodine + brown→blue

PROTEIN=add biurets reagent + blue→purple

REDUCING SUGARS=add benedict’s solution + brick red (present) but blue (not present)

when testing for reducing sugars what do you put the test tubes in

a hot water bath

effect of pH on rate of enzyme practical method

1. add amylase + buffer (specific pH)

2. add starch and start timer

3. drop mixture into iodine every 30 seconds

4. when iodine stops turning blue, starch is gone

5. repeat for different pH’s (not 7)

photosynthesis practical method

1. set up pondweed and place elodea in test tube with sodium hydrogen carbonate

2. move lamp to set distance

3. start timer and count oxygen bubbles made for 1 min

4. repeat with different distances