Biology Edexcel Pro Final Exam Questions Fully Solved 2024.

1. Investigate the effect of caffeine on heart rate of Daphnia - Topic 1 - Answer Daphnia of same species Placed on microscopic tray in pond water in bits of cotton and allowed to acclimatise for 5 minutes Then BPM counted using tally marks of a sheet of paper for 15 seconds, x4 to give BPM 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 - Answer 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 - Answer 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