1.3: Carbohydrates - disaccharides and polysaccharides

Question 1

Monosaccharides can also be combined in much larger numbers to form polysaccharides.

In carbohydrates, the monomer unit is called what?

Answer 1

In carbohydrates, the monomer unit is called a monosaccharide

Question 2

Pairs of monosaccharides can also be combined to form a disaccharide.

For example, glucose joined to glucose forms what?

Answer 2

For example, glucose joined to glucose forms maltose

Question 3

Pairs of monosaccharides can also be combined to form a disaccharide.

For example, glucose joined to fructose forms what?

Answer 3

For example, glucose joined to fructose forms sucrose

Question 4

Pairs of monosaccharides can also be combined to form a disaccharide.

For example, glucose joined to galactose forms what?

Answer 4

For example, glucose joined to galactose forms lactose

Question 5

Pairs of monosaccharides can also be combined to form a disaccharide.

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

Answer 5

When the monosaccharides join, a molecule of water is removed

Question 6

Pairs of monosaccharides can also be combined to form a disaccharide.

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

Answer 6

When the monosaccharides join, a molecule of water is removed and the reaction is therefore called a condensation reaction

Question 7

Condensation reaction

Answer 7

A condensation reaction is a chemical process in which 2 molecules combine to form a more complex one with the elimination of a simple substance, usually water

Question 8

A condensation reaction is a chemical process in which 2 molecules combine to form a more complex one with the elimination of a simple substance, usually water.

Many what are formed by condensation reactions?

Answer 8

Many biological polymers are formed by condensation reactions

Question 9

A condensation reaction is a chemical process in which 2 molecules combine to form a more complex one with the elimination of a simple substance, usually water.

Many biological polymers, such as what, are formed by condensation reactions?

Answer 9

Many biological polymers, such as:

1. Polysaccharides
2. Polypeptides

,are formed by condensation reactions

Question 10

Pairs of monosaccharides can also be combined to form a disaccharide.

When the monosaccharides join, a molecule of water is removed and the reaction is therefore called a condensation reaction.

The bond that is formed is called what?

Answer 10

The bond that is formed is called a glycosidic bond

Question 11

Pairs of monosaccharides can also be combined to form a disaccharide.

When the monosaccharides join, a molecule of water is removed and the reaction is therefore called a condensation reaction.

The bond that is formed is called a glycosidic bond.

When water is added to a disaccharide under suitable conditions, it does what?

Answer 11

When water is added to a disaccharide under suitable conditions, it breaks the glycosidic bond, releasing the constituent monosaccharides

Question 12

Pairs of monosaccharides can also be combined to form a disaccharide.

When the monosaccharides join, a molecule of water is removed and the reaction is therefore called a condensation reaction.

The bond that is formed is called a glycosidic bond.

When water is added to a disaccharide under suitable conditions, it breaks the glycosidic bond, releasing the constituent monosaccharides.

What is this called?

Answer 12

This is called hydrolysis

Question 13

Hydrolysis

Answer 13

Hydrolysis is the breaking down of large molecules into smaller ones by the addition of water molecules

Question 14

Be clear about the difference between the terms ‘condensation’ and ‘hydrolysis.’

Both condensation and hydrolysis involve the use of water in reactions.

However, condensation is what, while hydrolysis is what?

Answer 14

1. Condensation is the giving out of water in reactions

,while

2. Hydrolysis is the taking in of water to split molecules in reactions

Question 15

Some disaccharides, like maltose, are what?

Answer 15

Some disaccharides, like maltose, are reducing sugars

Question 16

Some disaccharides, like maltose, are reducing sugars.

To detect these we use the Benedict’s test.

Other disaccharides, like sucrose, are known as what?

Answer 16

Other disaccharides, like sucrose, are known as non-reducing sugars

Question 17

Some disaccharides, like maltose, are reducing sugars.

To detect these we use the Benedict’s test.

Other disaccharides, like sucrose, are known as non-reducing sugars, because they what?

Answer 17

Other disaccharides, like sucrose, are known as non-reducing sugars, because they do not change the colour of Benedict’s reagent when they are heated with it

Question 18

Some disaccharides, like maltose, are reducing sugars.

To detect these we use the Benedict’s test.

Other disaccharides, like sucrose, are known as non-reducing sugars, because they do not change the colour of Benedict’s reagent when they are heated with it.

In order to detect a non-reducing sugar, it must first be what?

Answer 18

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis

Question 19

Some disaccharides, like maltose, are reducing sugars.

To detect these we use the Benedict’s test.

Other disaccharides, like sucrose, are known as non-reducing sugars, because they do not change the colour of Benedict’s reagent when they are heated with it.

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be what?

Answer 19

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a:

1. Pestle
2. Mortar

Question 20

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add what to what?

Answer 20

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in:

1. A test tube
2. Filter

Question 21

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube where for how long?

Answer 21

Place the test tube in a gently boiling water bath for 5 minutes

Question 22

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains what), then what?

Answer 22

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present

Question 23

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add what to what?

Answer 23

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube

Question 24

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube where for how long?

Answer 24

1. Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube
2. Place the test tube in a gently boiling water bath for 5 minutes

Question 25

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will do what?

Answer 25

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides

Question 26

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Slowly add what to what in order to neutralise the hydrochloric acid?

Answer 26

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid

Question 27

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Why do you slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid?

Answer 27

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid, because Benedict’s reagent will not work in acidic conditions

Question 28

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid, because Benedict’s reagent will not work in acidic conditions.

Test with what to check what?

Answer 28

Test with pH paper to check that the solution is alkaline

Question 29

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid, because Benedict’s reagent will not work in acidic conditions.

Test with pH paper to check that the solution is alkaline.

Re-test the resulting solution by doing what?

Answer 29

Re-test the resulting solution by heating it with 2cm³ of Benedict’s reagent in a gently boiling water bath for 5 minutes

Question 30

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid, because Benedict’s reagent will not work in acidic conditions.

Test with pH paper to check that the solution is alkaline.

Re-test the resulting solution by heating it with 2cm³ of Benedict’s reagent in a gently boiling water bath for 5 minutes.

If a non-reducing sugar was present in the original sample, the Benedict’s reagent will now do what?

Answer 30

If a non-reducing sugar was present in the original sample, the Benedict’s reagent will now turn orange-brown

Question 31

In order to detect a non-reducing sugar, it must first be hydrolysed into its monosaccharide components by hydrolysis.

The process is carried out as if the sample is not already in liquid form, it must first be ground up in water with a pestle and mortar.

Add 2cm³ of the food sample being tested to 2cm³ of Benedict’s reagent in a test tube and filter.

Place the test tube in a gently boiling water bath for 5 minutes.

If the Benedict’s reagent does not change colour (the solution remains blue), then a reducing sugar is not present.

Add another 2cm³ of the food sample to 2cm³ of dilute hydrochloric acid in a test tube and place the test tube in a gently boiling water bath for 5 minutes.

The dilute hydrochloric acid will hydrolyse any disaccharide present into its constituent monosaccharides.

Slowly add some sodium hydrogencarbonate solution to the test tube in order to neutralise the hydrochloric acid, because Benedict’s reagent will not work in acidic conditions.

Test with pH paper to check that the solution is alkaline.

Re-test the resulting solution by heating it with 2cm³ of Benedict’s reagent in a gently boiling water bath for 5 minutes.

If a non-reducing sugar was present in the original sample, the Benedict’s reagent will now turn orange-brown.

The Benedict’s reagent now turning orange-brown if a non-reducing sugar was present in the original sample is due to what?

Answer 31

The Benedict’s reagent now turning orange-brown if a non-reducing sugar was present in the original sample is due to the reducing sugars that were produced from the hydrolysis of the non-reducing sugar

Question 32

Polysaccharides are polymers, formed by combining together many monosaccharide molecules.

The monosaccharides are joined by glycosidic bonds that were formed by condensation reactions.

As polysaccharides are very large molecules, they are what?

Answer 32

As polysaccharides are very large molecules, they are insoluble

Question 33

Polysaccharides are polymers, formed by combining together many monosaccharide molecules.

The monosaccharides are joined by glycosidic bonds that were formed by condensation reactions.

As polysaccharides are very large molecules, they are insoluble.

This feature makes them suitable for what?

Answer 33

This feature makes polysaccharides suitable for storage

Question 34

Polysaccharides are polymers, formed by combining together many monosaccharide molecules.

The monosaccharides are joined by glycosidic bonds that were formed by condensation reactions.

As polysaccharides are very large molecules, they are insoluble.

This feature makes them suitable for storage.

When they are hydrolysed, polysaccharides do what?

Answer 34

When they are hydrolysed, polysaccharides break down into:

1. Disaccharides

Or,

2. Monosaccharides

Question 35

Polysaccharides are polymers, formed by combining together many monosaccharide molecules.

The monosaccharides are joined by glycosidic bonds that were formed by condensation reactions.

As polysaccharides are very large molecules, they are insoluble.

This feature makes them suitable for storage.

When they are hydrolysed, polysaccharides break down into disaccharides or monosaccharides.

Some polysaccharides, such as cellulose, are what?

Answer 35

Some polysaccharides, such as cellulose, are not used for storage

Question 36

Polysaccharides are polymers, formed by combining together many monosaccharide molecules.

The monosaccharides are joined by glycosidic bonds that were formed by condensation reactions.

As polysaccharides are very large molecules, they are insoluble.

This feature makes them suitable for storage.

When they are hydrolysed, polysaccharides break down into disaccharides or monosaccharides.

Some polysaccharides, such as cellulose, are not used for storage, but do what?

Answer 36

Some polysaccharides, such as cellulose, are not used for storage, but give structural support to plant cells

Question 37

Polysaccharides illustrate an important principle, that a few basic monomer units can be what to give what?

Answer 37

Polysaccharides illustrate an important principle, that a few basic monomer units can be combined in a number of different ways to give a large range of different biological molecules

Question 38

Starch is a polysaccharide that is found in many parts of plants in the form of what?

Answer 38

Starch is a polysaccharide that is found in many parts of plants in the form of small:

1. Granules

Or,

2. Grains

Question 39

Starch is a polysaccharide that is found in many parts of plants in the form of small granules or grains.

Example

Answer 39

For example, starch grains in chloroplasts

Question 40

Starch is a polysaccharide that is found in many parts of plants in the form of small granules or grains.

It is formed by what?

Answer 40

Starch is formed by the joining of between:

1. 200
2. 100,000

a-glucose molecules by glycosidic bonds in a series of condensation reactions

Question 41

Starch is easily detected by its ability to do what?

Answer 41

Starch is easily detected by its ability to change the colour of the iodine in potassium iodide solution from:

1. Yellow

to

2. Blue-black

Question 42

Starch is easily detected by its ability to change the colour of the iodine in potassium iodide solution from yellow to blue-black.

The test is carried out at what temperature?

Answer 42

The test is carried out at room temperature

Question 43

Starch is easily detected by its ability to change the colour of the iodine in potassium iodide solution from yellow to blue-black.

The test is carried out at room temperature.

The test is carried out as you place what into a test tube or do what?

Answer 43

The test is carried out as you:

1. Place 2cm³ of the sample being tested into a test tube

Or,

2. Add 2 drops of the sample into a depression on a spotting tile

Question 44

Starch is easily detected by its ability to change the colour of the iodine in potassium iodide solution from yellow to blue-black.

The test is carried out at room temperature.

The test is carried out as you place 2cm³ of the sample being tested into a test tube or add 2 drops of the sample into a depression on a spotting tile.

Add what and do what?

Answer 44

1. Add 2 drops of iodine solution
2. Shake or stir

Question 45

Starch is easily detected by its ability to change the colour of the iodine in potassium iodide solution from yellow to blue-black.

The test is carried out at room temperature.

The test is carried out as you place 2cm³ of the sample being tested into a test tube or add 2 drops of the sample into a depression on a spotting tile.

Add 2 drops of iodine solution and shake or stir.

The presence of starch is indicated by a what?

Answer 45

The presence of starch is indicated by a blue-black coloration

Question 46

The terms ‘condensation’ and ‘hydrolysis.’

Both involve the use of water in reactions.

However, condensation is the what of water in reactions, while hydrolysis is the what of water to split molecules in reactions?

Answer 46

1. Condensation is the giving out of water in reactions

,while

2. Hydrolysis is the taking in of water to split molecules in reactions

Question 47

The function of glucose is that it is what?

Answer 47

The function of glucose is that it is the main sugar used in respiration

Question 48

The function of glucose is that it is the main sugar used in respiration.

What are polymers of glucose?

Answer 48

1. Starch
2. Glycogen

are polymers of glucose

Question 49

The function of glucose is that it is the main sugar used in respiration.

Starch and glycogen are polymers of glucose.

Glucose is what in the bloodstream to cells?

Answer 49

Glucose is:

1. Absorbed
2. Transported

in the bloodstream to cells

Question 50

What is the function of galactose?

Answer 50

The function of galactose is that it is used mainly in our diet as part of the lactose disaccharide

Question 51

What is the function of fructose?

Answer 51

The function of fructose is that it is a sugar found naturally in:

1. Fruit
2. Honey
3. Some vegetables

Question 52

What are monosaccharides used for in the body?

Answer 52

Monosaccharides are used to provide a rapid source of energy in the body

Question 53

Monosaccharides are used to provide a rapid source of energy in the body.

Why are they so useful for this job?

Answer 53

Monosaccharides are so useful for this job, because they:

1. Are readily absorbed
2. Require little to no change for use in respiration

Question 54

What is the function of sucrose?

Answer 54

The function of sucrose is that it is the form in which sugar is transported around the plant

Question 55

Maltose is made of 2 glucose monomers.

When is maltose produced?

Answer 55

Maltose is produced when amylase breaks down starch

Question 56

Why does it take us longer to use disaccharides in respiration?

Answer 56

It takes us longer to use disaccharides in respiration, because disaccharides need to be digested before they can be used to produce energy

Question 57

It takes us longer to use disaccharides in respiration, because disaccharides need to be digested before they can be used to produce energy.

What are often stored in this form?

Answer 57

Sugars are often stored in this form

Question 58

Like disaccharides, polysaccharides are formed by what?

Answer 58

Like disaccharides, polysaccharides are formed by condensation reactions

Question 59

Polysaccharides are mainly used as what?

Answer 59

Polysaccharides are mainly used as:

1. An energy store
2. Structural components of cells

Question 60

The major polysaccharides are what in plants and what in animals?

Answer 60

The major polysaccharides are:

1. Starch and cellulose in plants
2. Glycogen in animals

Question 61

One role of lactose in living organisms

Answer 61

One role of lactose in living organisms is that it is the carbohydrate source in mammalian milk