Unit 1 - Monomers+Polymers

Question 1

Definition of a monomer?

Answer 1

Monomers are the small soluble molecules from which larger molecules are made.

Question 2

Definition of a polymer?

Answer 2

Polymers are molecules made from a large number of similar monomers joined together.

Question 3

What is a condensation reaction?

Answer 3

A reaction that joins 2 molecules together with the formation of a chemical bond and involves the release of a water molecule.

Question 4

What is a hydrolysis reaction?

Answer 4

A reaction that breaks a chemical bond between 2 molecules and involves the use of a water molecule.

Question 5

What are monosaccharides and provide 3 examples?

Answer 5

Monosaccharides are the monomers from which larger carbohydrates are made. Glucose, galactose and fructose are common monosaccharides. They all have the same formula of C6H12O6

Question 6

What bond does a condensation reaction between 2 monosaccharides form?

Answer 6

A glycosidic bond.

Question 7

What are the 2 isomers of glucose?

Answer 7

Alpha-glucose and beta-glucose

Question 8

Structure of alpha-glucose?

Question 9

Structure of beta-glucose?

Question 10

How are disaccharides formed and what is their formula?

Answer 10

They’re formed by the condensation of 2 monosaccharides. They all have the same formula of C12H22011 (C6H12O6+C6H12O6) (the removal of a H2O molecule)

Question 11

What monosaccharides is maltose made from?

Answer 11

Glucose + glucose

Question 12

What monosaccharides is lactose made from?

Answer 12

Galactose + Glucose

Question 13

What monosaccharides is sucrose made from?

Answer 13

Glucose + Fructose

Question 14

Equation for the formation of a disaccharide?

Answer 14

C6H12O6 + C6H12O6 = C12H22O11 + H2O

Question 15

Why does a condensation reaction between 2 monosaccharides form a 1,4 glycosidic bond?

Answer 15

The reaction occurs between the OH groups on carbon 4 of one monosaccharide and carbon 1 on the other monosaccharide. This creates a 1,4 glycosidic bond.

Question 16

Equation for the hydrolysis of disaccharides?

Answer 16

C12H22O11 + H2O = C6H12O6 + C6H12O6

Question 17

3 examples of polysaccharides?

Answer 17

Glycogen + starch = storage
Cellulose = structural

Question 18

What is starch made from? And what is it used for?

Answer 18

It is a polysaccharide of alpha glucose. And is the storage carbohydrate in plants.

Question 19

What are the properties of starch and how does this relate to its function? (6marks)

Answer 19

Insoluble - does not affect osmosis/does not diffuse across the cell membrane and out of cells.
Coiled into a helix - compact so a lot can fit into a small space.
1,4 and 1,6 glycosidic bonds - allows branching to occur.
Branched - provides many ends for faster hydrolysis by enzymes to form alpha-glucose for use in respiration.

Question 20

What are the 2 parts of starch and their functions?

Answer 20

Amylose - helix structure + 1,4 glycosidic bonds.
Amylopectin - 1,4 glycosidic bonds + 1,6 glycosidic bonds which allows branching to occur.

Question 21

What is glycogen a polymer of? And what is it used for?

Answer 21

It is a polymer of alpha glucose. It is the storage carbohydrate in animals.

Question 22

How does glycogen differ from starch? How do these features benefit glycogen?

Answer 22

It has shorter chains.
It is more highly branched.
It has a larger surface area.
These features lead to glycogen being more readily hydrolysed into glucose for respiration. This is more important in animals as they move more than plants.

Question 23

How does the structure of starch relate to its function? (6 marks)

Answer 23

Insoluble - does not affect osmosis/does not diffuse across the cell membrane and out of cells.
Coiled into a helix - compact so a lot can fit into a small space.
1,4 + 1,6 glycosidic bonds - allows branching to occur.
Very highly branched - provides many ends for faster hydrolysis by enzymes to form alpha-glucose for use in respiration.

Question 24

What is cellulose a polymer of?

Answer 24

Beta-glucose

Question 25

How does beta-glucose differ from alpha-glucose?

Answer 25

The position of the H and Oh groups on carbon 1 are inverted.

Question 26

What’s special about beta-glucose molecules in condensation reactions?

Answer 26

Every other beta-glucose molecule flips 180degrees to allow OH groups on carbon 1 and 4 to be adjacent to each other to form a glycosidic bond.

Question 27

How is a cellulose cell wall formed?

Answer 27

Several chains of cellulose are joined together in layers; these chains are held together by the formation of hydrogen bonds formed between OH groups. Hundreds of these chains are then held together by hydrogen bonds to form microfibrils. Microfibrils form hydrogen bonds between other microfibrils and together to form a cellulose fibre. Cellulose fibres are woven to form a cellulose cell wall.

Question 28

How does the structure of cellulose relate to its function?

Answer 28

Only 1,4 glycosidic bonds present-allows formation of long, straight, unbranched chains of beta-glucose.
Long, straight, unbranched chains of beta-glucose-allows formation of many hydrogen bonds so microfibrils are created.
Many microfibrils and cellulose fibres and many hydrogen bonds-provides strength to the cell wall.

Question 29

What is the Benedict’s test for reducing sugars?

Answer 29

1) Add Benedict’s solution to sample and heat to 95degrees.
2) A colour change from blue to green/yellow/orange/red precipitate indicates the presence of reducing sugar.

Question 30

How could you use this test to get a quantitative measurement?

Answer 30

1) Filter off the precipitate
2) Dry and weigh it

Question 31

Benedict’s test for non-reducing sugars?

Answer 31

1) Add Benedict’s solution to sample and heat to 95degrees and if there is no change in the Benedict’s test for reducing sugar, boil a fresh sample with dilute HCl acid for a few mins to hydrolyse the glycosidic bonds.
2) Neutralise, by adding solid sodium hydrogen carbonate.
3) Then add Benedict’s reagent and heat to 95degrees.
4) A colour change from blue to a red precipitate.

Question 32

What is the test for starch?

Answer 32

Iodine solution test.
1) Add iodine in potassium iodide solution to your sample.
2) A colour change from orange to blue-black indicates the presence of starch.