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

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 19

As polysaccharides are very large molecules, they are insoluble

Question 20

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 20

This feature makes polysaccharides suitable for storage

Question 21

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 21

When they are hydrolysed, polysaccharides break down into:

1. Disaccharides

Or,

2. Monosaccharides

Question 22

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 22

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

Question 23

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 23

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

Question 24

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

Answer 24

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 25

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

Answer 25

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

1. Granules

Or,

2. Grains

Question 26

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

Example

Answer 26

For example, starch grains in chloroplasts

Question 27

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 27

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 28

Starch is easily detected by its ability to do what?

Answer 28

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 29

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 29

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 30

The function of glucose is that it is what?

Answer 30

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

Question 31

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

What are polymers of glucose?

Answer 31

1. Starch
2. Glycogen

are polymers of glucose

Question 32

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 32

Glucose is:

1. Absorbed
2. Transported

in the bloodstream to cells

Question 33

What is the function of galactose?

Answer 33

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

Question 34

What is the function of fructose?

Answer 34

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

1. Fruit
2. Honey
3. Some vegetables

Question 35

What are monosaccharides used for in the body?

Answer 35

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

Question 36

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

Why are they so useful for this job?

Answer 36

Monosaccharides are so useful for this job, because they:

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

Question 37

What is the function of sucrose?

Answer 37

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

Question 38

Maltose is made of 2 glucose monomers.

When is maltose produced?

Answer 38

Maltose is produced when amylase breaks down starch

Question 39

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

Answer 39

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

Question 40

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 40

Sugars are often stored in this form

Question 41

Like disaccharides, polysaccharides are formed by what?

Answer 41

Like disaccharides, polysaccharides are formed by condensation reactions

Question 42

Polysaccharides are mainly used as what?

Answer 42

Polysaccharides are mainly used as:

1. An energy store
2. Structural components of cells

Question 43

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

Answer 43

The major polysaccharides are:

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

Question 44

One role of lactose in living organisms

Answer 44

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