1.3- CARBOHYDRATES- DISACCHARIDES AND POLYSACCHARIDES

Question 1

What does glucose joined to glucose form?

Answer 1

maltose

Question 2

What does glucose joined to fructose form?

Answer 2

sucrose

Question 3

What does glucose joined to galactose form?

Answer 3

lactose

Question 4

When the monosaccharides join, a molecule of water is removed, what is the reaction?

Answer 4

condensation reaction

Question 5

What is the bond formed called?

Answer 5

glycosidic bond

Question 6

What is it called when water is added to disaccharide under suitable conditions and it breaks the glycosidic bond releasing the constituent monosaccharides?

Answer 6

hydrolysis

Question 7

E.g. of disaccharides that are non-reducing sugars?

Answer 7

sucrose

Question 8

What are non-reducing sugars?

Answer 8

do not change colour of Benedict’s reagent when heated with it

Question 9

What must be done in order to detect a non-reducing sugar?

Answer 9

must be first hydrolysed into its monosaccharide components by hydrolysis

Question 10

What are polysaccharides?

Answer 10

polymers formed by combining together many monosaccharide molecules

Question 11

How are the monosaccharides joined by?

Answer 11

glycosidic bonds

Question 12

Property of polysaccharides as they are very large molecules?

Answer 12

insoluble

Question 13

How does them being insoluble fit them for a certain purpose?

Answer 13

for storage

Question 14

What happens when polysaccharides are hydrolysed?

Answer 14

break down into disaccharides or monosaccharides

Question 15

Type of polysaccharide not used for storage and purpose?

Answer 15

cellulose

give structural support to plant cells

Question 16

What is starch?

Answer 16

polysaccharide found in many parts of plants in form of small granules or grains

Question 17

Example of where starch can be found

Answer 17

starch grains in chloroplasts

Question 18

How is starch formed?

Answer 18

joining of between 200 and 100 000 α-glucose molecules by glycosidic bonds in a series of condensation reactions

Question 19

How is starch easily detected?

Answer 19

its ability to change colour of iodine in potassium iodide solution from yellow to blue-black

Question 20

What temperature is the test for starch carried out in?

Answer 20

room temperature