1.2 Carbohydrates and monosaccharides

Question 1

What is the basic unit of a sugar called

Answer 1

Saccharide

Question 2

What is a single monomer of sugar called

Answer 2

A monosaccharide

Question 3

What is a pair of monosaccharides called after a condensation reaction, joining them

Answer 3

A disaccharide

Question 4

What can more than 2 monosaccharides form after a condensation reaction, joining them

Answer 4

Polysaccharides

Question 5

What are some properties of monosaccharides

Answer 5

They are sweet tasting, soluble substances, have the general formula (CH2O)n where n can be any number from 3-7

Question 6

What are 3 examples of monosaccharides

Answer 6

Glucose, fructose, galactose

Question 7

What does Glucose + Glucose make

Answer 7

Maltose

Question 8

What does glucose + fructose make

Answer 8

Sucrose

Question 9

What does glucose + galactose make

Answer 9

Lactose

Question 10

What are the two isomers of glucose

Answer 10

α - glucose

β - glucose

Question 11

What is the name for the test for testing for reducing sugars

Answer 11

Benedict’s test

Question 12

What sugars are reducing sugars

Answer 12

All monosaccharides and maltose

Question 13

What is a reducing sugar

Answer 13

A sugar that can donate electrons to another chemical

Question 14

What is Benedict’s reagent

Answer 14

An alkaline solution of copper(II) sulfate.

Question 15

Give three examples of Hexoses

Answer 15

Glucose, fructose, galactose

Question 16

Give two examples of pentoses

Answer 16

Ribose

Deoxyribose

Question 17

What is the formula of a disaccharide

Answer 17

C12H22O11

Question 18

what is the test for a reducing sugar

Answer 18

add the food sample in a liquid or aqueous form to an equal volume of Benedict’s reagent. Heat the mixture gently in a boiling water bath for 5 mins. If a reducing sugar is present an orange-brown colour is formed.

Question 19

what is the test for a non-reducing sugar

Answer 19

add the food sample to dilute hydrochloric acid. Heat the mixture gently in a boiling water bath for 5 mins. The HCL will hydrolyse any disaccharides. Slowly add some sodium hydrogencarbonate (NaHCO3) in order to neutralise the acid. Test with PH paper to check that the solution is alkaline. retest the solution by adding the food sample in a liquid or aqueous form to an equal volume of Benedict’s reagent. Heat the mixture gently in a boiling water bath for 5 mins. If a reducing sugar is present an orange-brown colour is formed.

Question 20

what is the test for starch

Answer 20

place the sample in a test tube or add two drops of the sample to a spotting tile. add two drops of iodine solution and shake or stir. a positive test will go blue-black.