2.2.12 practical biochem 1: qualitative tests for bio molecules

Question 1

name the qualitative tests for bio molecules

Answer 1

(carbohydrates:)
- starch
- reducing sugars
- non-reducing sugars
(other:)
- testing for lipids
- testing for proteins

Question 2

how do you test for starch

Answer 2

1. add iodine solution (in potassium iodide) to sample

Question 3

results for starch test

Answer 3

positive
= colour change from yellow-brown to blue-black

Question 4

reasoning behind colour change when starch is present

Answer 4

• when dissolved in potassium iodide, iodine (I2) forms triiodide ions I3-
• slips into middle of amylose helix