edexcel AS biology unit 1 experiements

1) Prepare a range of different concentrations of caffiene solution (maximum of 10) and a control solution (with no caffiene)

2) Transfer one Daphnia to the rounded dip of a cavity slide

3) Place the cavity slide on a light microscope, with low magnification focusing on the Daphnia's heart

4) Add one drop (using a pipette) of the caffiene solution on the Daphnia

5) Count the number of heartbeats in 10 seconds. You can then x 6 to get the number of heartbeats per one minute

6) Keep other factors constant (temperature, volume of caffiene concentration)

7) Repeat steps 2 - 6 with the other caffiene concentrations

8) Compare the results of the different caffiene concentrations

~ this experiment is very similar to a TITRATION

1)Prepare vitamin C solutions of different concentrations (maximum 10)  in conical flasks

2) Measure an equal volume of DCPIP (a blue dye, which turns colourless in the presence of vitamin C) with a set concentration in a burette. Record the intial volume of DCPIP

3) Place the conical flask under the burette containing the DCPIP

4) Add one drop of DCPIP at a time, to the conical flask, shaking the flask gently. Continue adding the DCPIP until the solution in the flask goes colourless

5) Record the final volume of DCPIP and calculate the mean titre of DCPIP

6) Repeat steps 2 - 5 twice with the same vitamin C concentration and take an average of the 3 mean titre readings

7) Keep other factors constant (temperature, volume of vitamin C)

8) Repeat steps 2 - 5 with the other vitamin C concentrations

1) Cut pieces of beetroot (maximum 10), rinse and blot them using a towel to remove pigment released when cutting

2) Place the beetroot pieces in different test tubes, and add 5cm3 of water in each test tube

3) Place each test tube in water baths each with different temperatures (maximum 10) leaving them for the same time

4) Remove the beetroot from the test tubes, and leave the coloured liquid behind in the test tubes

5) Use a colorimeter- a machine which passes light through the coloured liquid and measures the amount of light absorbed. The higher the absorbance -->more the pigment released-->higher the permeability of membrane

6) Keep other factors constant (volume of water, size of food(beetroot) and volume of alcohol)

~ 2H2O2 -----------> 2H2O + O2

1) Set up the experiment with a 'upside down' measuring cylinder, in a large container (which is filled with water).

2) Prepare a test tube with a set volume of a concentration of Catalase (enzyme) and a set volume of hydrogen peroxide (substrate). Shake the test tube

2) Attach a delivery tube at the base of the measuring cylinder to the test tube (through an open hole stopper)

4) Measure the amount of oxygen given off in the first minute of reaction, by measuring the volume of water rising in the measuring cylinder

5) To calculate initial rate of reaction; volume of oxygen produced (cm3) / time (in min)

6) More oxygen produced--> faster the initial rate of reaction

7) Repeat steps 1-5 using different enzyme concentrations (maximum 10)

8) Keep other factors constant (temperature, pH, substrate concentration)