Biology Edexcel Practicals A Level Questions With
Complete Solutions
1. Investigate the effect of caffeine on heart rate of Daphnia - Topic 1
Daphnia of same species and volume
Placed on microscopic tray in pond water in bits of cotton and allowed to acclimatise
for 5 minutes
Then HR counted using tally marks of a sheet of paper for 15 seconds, x4 to give
hr/min
repeated with unknown conc. of caffeine (blind)
0.0% and distilled water, 0.1% and 0.5%
Repeat with each daphnia and with other daphnia calculate mean
2. Investigate the vitamin C content of food and drink - Topic 1
Use Titration
Pipette 5cm3 of DCPIP into a conical flask and place on a white tile under burette
(filled with juice)
Read start volume of juice
Add juice drop by drop swirling conical flask unitil blue colour of DCPIP turns
colourless
Subtract start volume of juice from final volume
Repeat with same juice then with other juice
Using a standard curve calculate conc. of vitamin C
3. Investigate the membrane structure and the effect of temperature on
membrane permeability - Topic 2
Use beetroot of the same species or plant cut cylindrical samples using a size 4 cork
bore, then cut into 1cm sections
Place in distilled water overnight
Labelled boiling tubes filled with 5cm3 of distilled water into water baths
(0,10,20,30,40,50,60,70)
Place one beetroot section into each tube and leave for 30mins
Carefully remove beetroot(no squeezing) and shake water to disperse dye
Put 2cm3 distilled water into curvette and put in colorimeter set to %absorption on
, blue/green filter
Adjust to 0 for distilled water
Add 2cm3 of of dye, not changing any settings and read % absorbency
4. Investigate the effect of enzyme and substrate conc. on the initial rate of
reactions - Topic 2
Pipette 8cm3 trypsin and 2cm3 of distilled water into a boiling tube (0.4%), then 6, 4
(0.3%), then 4, 6 (0.2%)
Use a colorimeter and fill with distilled water in a curvette and set to % transmission
at 440nm filter
Pipette 2cm3 of of milk into beaker, then 2cm3 of 0.5% trypsin into into another
beaker
Transfer milk into trypsin and immediately transfer to curvette, place in colorimeter
and press 'T'
record results to 2 dp
record % transmission every 10 secs, stop at 3mins
Repeat for all conc. 0.5-0.2
5.Prepare and stain a root tip squash to observe the stages of mitosis - Topic 3
Cut 5mm off of garlic root tips (white healthy tips)
Soak tips in 2cm of 1M hydrochloric acid for 5 minutes
Put tips in 5cm of distilled water for 4-5mins
transfer one of the tips to a microscope slide
Break up the tip with a mounted needle add a drop of toluidine blue and leave for 2
mins
cover with coverslip and blot with several layers of tissue and press gently to spread
cells
view under microscope fot cell with visible chromosomes
Repeat and calculate mitiotic index or the number of cells in a certain phase
6. Identify sclerencyhma fibres, phloem sieve tubes and xylem vessels and
their location within stems through a light microscope - Topic 4
cut a stem widthways into a thin strip, place on a microscope slide with a cover slip
ontop
Place under microscope
Complete a high power and low power drawing of the vascular bundle
7. Investigate plant mineral deficiencies - Topic 4
Complete Solutions
1. Investigate the effect of caffeine on heart rate of Daphnia - Topic 1
Daphnia of same species and volume
Placed on microscopic tray in pond water in bits of cotton and allowed to acclimatise
for 5 minutes
Then HR counted using tally marks of a sheet of paper for 15 seconds, x4 to give
hr/min
repeated with unknown conc. of caffeine (blind)
0.0% and distilled water, 0.1% and 0.5%
Repeat with each daphnia and with other daphnia calculate mean
2. Investigate the vitamin C content of food and drink - Topic 1
Use Titration
Pipette 5cm3 of DCPIP into a conical flask and place on a white tile under burette
(filled with juice)
Read start volume of juice
Add juice drop by drop swirling conical flask unitil blue colour of DCPIP turns
colourless
Subtract start volume of juice from final volume
Repeat with same juice then with other juice
Using a standard curve calculate conc. of vitamin C
3. Investigate the membrane structure and the effect of temperature on
membrane permeability - Topic 2
Use beetroot of the same species or plant cut cylindrical samples using a size 4 cork
bore, then cut into 1cm sections
Place in distilled water overnight
Labelled boiling tubes filled with 5cm3 of distilled water into water baths
(0,10,20,30,40,50,60,70)
Place one beetroot section into each tube and leave for 30mins
Carefully remove beetroot(no squeezing) and shake water to disperse dye
Put 2cm3 distilled water into curvette and put in colorimeter set to %absorption on
, blue/green filter
Adjust to 0 for distilled water
Add 2cm3 of of dye, not changing any settings and read % absorbency
4. Investigate the effect of enzyme and substrate conc. on the initial rate of
reactions - Topic 2
Pipette 8cm3 trypsin and 2cm3 of distilled water into a boiling tube (0.4%), then 6, 4
(0.3%), then 4, 6 (0.2%)
Use a colorimeter and fill with distilled water in a curvette and set to % transmission
at 440nm filter
Pipette 2cm3 of of milk into beaker, then 2cm3 of 0.5% trypsin into into another
beaker
Transfer milk into trypsin and immediately transfer to curvette, place in colorimeter
and press 'T'
record results to 2 dp
record % transmission every 10 secs, stop at 3mins
Repeat for all conc. 0.5-0.2
5.Prepare and stain a root tip squash to observe the stages of mitosis - Topic 3
Cut 5mm off of garlic root tips (white healthy tips)
Soak tips in 2cm of 1M hydrochloric acid for 5 minutes
Put tips in 5cm of distilled water for 4-5mins
transfer one of the tips to a microscope slide
Break up the tip with a mounted needle add a drop of toluidine blue and leave for 2
mins
cover with coverslip and blot with several layers of tissue and press gently to spread
cells
view under microscope fot cell with visible chromosomes
Repeat and calculate mitiotic index or the number of cells in a certain phase
6. Identify sclerencyhma fibres, phloem sieve tubes and xylem vessels and
their location within stems through a light microscope - Topic 4
cut a stem widthways into a thin strip, place on a microscope slide with a cover slip
ontop
Place under microscope
Complete a high power and low power drawing of the vascular bundle
7. Investigate plant mineral deficiencies - Topic 4
