biochemical tests

Question 1

protein

Answer 1

-add biuret
-results; purple

Question 2

starch

Answer 2

-add iodine with potassium iodide
-results ; orange to blue - black

Question 3

test for reducing sugars [monosaccharides and lactose and maltose]

Answer 3

-add benedicts reagent = heat
-positive test ; blue to green, yellow, orange or brick red

Question 4

non reducing sugars [sucrose]

Answer 4

• heat sample with Benedicts reagent
  -sample stays blue so negative
• heat a new sample and add dilute hydrochloric acid
  -once cooled, neutralise the acid to an alkaline [ sodium hydrogen carbonate]
  -positive result; blue to green , orange or brick red

Question 5

lipids

Answer 5

-dissolve sample in ethanol
- shake
-then add distilled water
-shake
-results ; white emulsion