Question

1. if given unlabeled samples of glucose, malfose and lactose how could you identify each of the unknown? support your answer with test- glucose steips and barfoeds test.

2. how would glucose, maltose, lactose, lactose +acid, and lactose+ base react with an maltase pill? explain the levels of glucose.

3. starchws and fiber are two other sources of carbohydrates. How do they differ from sugars?

4. With the addition of a lactase enzyme glucose and maltose reacted but lactose did not. How does those results make sense?

5. Which pH condition( acidic, basic or neutral) results in the most succesful conversion of lactose to glucose? does the enzyme activity cease entirely, slow down, or remain the same when the pH changes?

Answer 1

ANSWERS :

1-

• If a sample of glucose,maltose and lactose given unlabeled, then we can identify each by using some qualitative chemical tests.
• Glucose is monosacharide ( one sugar unit ) were maltose and lactose are disacharides ( two sugar unit ) ie, [ maltose = glucose + glucose ] [ lactose = glucose + galactose ] \
• They are reduciong sugars , so we can perform BARFOEDS TEST to determine the number of sugar units.
• BARFOEDS TEST is generally used to identify the presence of monosacharides, it is based on REDUCTION of copper acetate to copper oxide. which gives a brick red precipitate. here only glucose gives the brick red precipitate and other to fails.
• But in order to differentiate glucose, maltose, and lactose respectively, one can perform OSAZONE TEST.
• OSAZONE TEST : when reducing sugars react with phenyl hydrazine it give specific osazone crystals. osazone test give following result under microscope,

1- Needle shaped crystals for glucose

2- Sunflower shaped crystals for maltose

3- Powder puff shaped crystals for lactose.

Therefore , using barfoeds test and osazone test, we can identify the unknown sugar samples.