2. Sugars

Question 1

what elements are all carbohydrates made of?

Answer 1

the elements C, H and O

Question 2

what are carbohydrates made from?

Answer 2

they are made from the monomer monosaccharides

Question 3

define an isomer

Answer 3

they are molecules that have the same molecular formula as each other but the atoms are connected differently

Question 4

give an example of an isomer

Answer 4

Glucose

Question 5

define a hexose sugar

Answer 5

a hexose sugar is a monosaccharide with six carbon atoms in each molecule

Question 6

name the two types of glucose

Answer 6

• Alpha Glucose
• Beta Glucose

Question 7

how is a disaccharide formed

Answer 7

when two monosaccharides are joined via a condensation reaction, glycosidic bonds are formed between the two monosaccharides as a water molecule is released- forming a disaccharide

Question 8

what is a disaccharide

Answer 8

two monosaccharides joined together

Question 9

what is the reagent for testing sugars?

Answer 9

Benedict’s reagent

Question 10

if the test for sugar is negative what could be present?

Answer 10

non-reducing sugars

Question 11

describe the test for reducing sugar

Answer 11

1. add benedicts reagant to a sample
2. heat it in a water bath thats been brought to boil
3. if the test is positive, it will form a coloured precipitate of either green, yellow, or brick-red

Question 12

give examples of reducing sugars

Answer 12

• monosaccharides
• some disaccharides i.e. maltose and lactose

Question 13

describe the process for testing for non-reducing sugars

Answer 13

1. get a new sample of a test solution, adding hydrochloric acid
2. place in water bath thats been brought to boil
3. neutralise it by adding hydrogen carbonate
4. finally carry out the Benedict’s solution test as you would with reducing sugars

Question 14

What bond is present in carbohydrates

Answer 14

Glycosidic bonds