Vitamin Content Practical

Question 1

What are free radicals?

Answer 1

• Atoms or molecules with one or more unpaired electrons
  = byproducts of metabolic reactions or reactions breaking down toxins

Question 2

Why are free radicals «bad»?

Answer 2

Large numbers of free radicals increase our chance of CHD because they oxidised lipoproteins; oxidised LDLs are more readily absorbed in plaque formation

Question 3

What do anti oxidants do?

Answer 3

Reduce radical damage which means less plaque formation

Question 4

Describe the steps in the Vitamin C content practical

Answer 4

1 pipette 1cm3 of 1% DCPIP solution into a test tube
2 Record start volume of 1% vitamin C solution in a burette. Add 1% vitamin C solution drop by drop to DCPIP solution, shaking after each drop. Continue until the blue colour of DCPIP disappears. Record end volume; subtract start volume from this to calculate volume of 1% vitamin C solution to decolourise DCPIP. Repeat and find the average
3 Repeat this procedure with different fruit juices.
4 1% Vitamin C solution contains 10mg of Vitamin C in 1.0cm3; calculate mass of vitamin C required to decolourise 1cm3 of DCPIP solution. Use this value to work out the quantity of Vitamin C each fruit juice contains in mg cm-3

Question 5

Why does Vitamin C decolourise DCPIP?

Answer 5

Vitamin C is anti oxidant and reduces (donates electrons to) DCPIP