1.3-carbohydrates- disaccharides and polysaccharides

Question 1

disaccharide

Answer 1

two monomers joint together with a condensation reaction

Question 2

what bond is formed in a condensation reaction?

Answer 2

glycosidic bond

Question 3

what reaction can break this glycosidic bond?

Answer 3

hydrolysis

Question 4

glucose + glucose

Answer 4

maltose

Question 5

glucose + fructose

Answer 5

sucrose

Question 6

glucose + galactose

Answer 6

lactose

Question 7

polysaccharides

Answer 7

formed from many glucose units joined together

Question 8

Some disaccharides as well as polysaccharides are non-reducing sugars. What is the test for non-reducing sugars?

Answer 8

carry out benedict’s test first then if colour does not change:

dilute hydrochloric acid to food sample and place in water bath- this hydrolyses into monosaccharides

sodium hydrocarbonate added to neutralise

Benedict’s test again

change from blue to brick red if non reducing sugar present

Question 9

give an example of a non-reducing sugar

Answer 9

sucrose

Question 10

test for starch

Answer 10

iodine test
positive test= blue/black colour

Question 11

test for starch

Answer 11

iodine test
positive test= blue/black colour

Question 12

give 3 features of polysaccharides

Answer 12

insoluble, very large, good storage molecule