topic 1- Monomers & Polymers and carbohyrdates

Question 1

What are monomers?

Answer 1

Monomers are the smaller units from which larger molecules are made.

Question 2

What are polymers?

Answer 2

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

Question 3

What are examples of monomers?

Answer 3

Monosaccharides, amino acids and nucleotides.

Question 4

What is a condensation reaction?

Answer 4

A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.

Question 5

What is a hydrolysis reaction?

Answer 5

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

Question 6

What are monosaccharides?

Answer 6

Monosaccharides are the monomers from which larger carbohydrates are made.

Question 7

What are examples of monosaccharides?

Answer 7

Glucose, galactose and fructose.

Question 8

what is formed between 2 monosaccharide and how?

Answer 8

A condensation reaction between two monosaccharides forms a glycosidic bond. A disaccharide is formed.

Question 9

How is maltose formed?

Answer 9

Maltose is a disaccharide formed by condensation of two glucose molecules.

Question 10

How is lactose formed?

Answer 10

Lactose is a disaccharide formed by condensation of a glucose molecule and a galactose molecule.

Question 11

How is sucrose formed?

Answer 11

Sucrose is a disaccharide formed by condensation of a glucose molecule and a fructose molecule.

Question 12

What is an isomer?

Answer 12

Two molecules with the same molecular formula but a different structure.

Question 13

what are the two isomers of glucose?

Answer 13

α-glucose and β-glucose.

Question 14

Describe the difference between alpha glucose and beta glucose.

Answer 14

Hydroxyl on alpha glucose is at the bottom. The hydroxyl on beta glucose is at the top.

Question 15

How are polysaccharide formed?

Answer 15

Polysaccharides are formed by the condensation of many glucose units.

Question 16

give examples of polysaccharides and how they are formed.

Answer 16

Glycogen and starch are formed by the condensation of α-glucose.
Cellulose is formed by the condensation of β-glucose.

Question 17

What is starch?

Answer 17

Starch is what plants store as excess glucose. When plants need more glucose for energy, starch is broken down into glucose.

Question 18

What mixture of polysaccharides does starch contain?

Answer 18

Amylose and Amylopectin.

Question 19

What is the structure and function of starch?

Answer 19

Amylose is a long, unbranched chain of alpha glucose, The angles of the glycosidic bonds give it a coiled structure. This makes it very compact.

Amylopectin is a long, branched chain of alpha glucose. Its has got many side branches.

Question 20

relate the structure of starch to its function.

Answer 20

The coiled and compact structure of amylose allows a lot of energy to be stored, therefore making it a good energy storage.
The side branches on amylopectin allow enzymes to break down the molecule and make it easier to break the glycosidic bonds. This means that energy can be released quicker for important functions like respiration.
Starch is insoluble in water so doesn’t affect water potential, so water cannot enter cells by osmosis, which would make them swell.

Question 21

What is the test for starch?

Answer 21

Add iodine dissolved in potassium iodide solution to the test sample. If starch is present the sample changes from browny- orange to a dark, blue-black colour.

Question 22

What is glycogen?

Answer 22

Glycogen is the main energy storage in animals and it stores excess glucose to be used later on, such as respiration.

Question 23

What is the structure of glycogen?

Answer 23

Glycogen has many side branches, similar to that of amylopectin.

Question 24

Relate the structure of glycogen to its function.

Answer 24

The side branches in glycogen allow it to be broken down much quicker by enzymes, meaning that energy can be released quickly as well.
Since it is highly branched, a high amount of energy is released. The energy released can be used for important processes such as respiration.
Glycogen is also insoluble and therefore do not affect the water potential, so water cannot enter by osmosis.

Question 25

What is cellulose?

Answer 25

Cellulose is the main component found in cell walls to help provide structural support.

Question 26

What is the structure of cellulose?

Answer 26

Cellulose is a long, straight, unbranched chain of beta glucose. Each chain is linked by hydrogen bonds to form strong fibres known as microfibrils.

Question 27

Relate the structure of cellulose to its function.

Answer 27

The microfibrils help provide structural support for the cell wall, meaning that it can help the cell wall to not burst when water tries to enter in.
The strength of the cell wall is contributed by the many hydrogen bonds that are between the cellulose chains, making cellulose a strengthening material for plants.
Insoluble so doesn’t affect the water potential so water cannot enter by osmosis.

Question 28

What is the test for reducing sugars?

Answer 28

Add benedict reagent to the test sample.
Heat it in a water bath.
If reducing sugar is present, the solution will turn brick-red.
If the solution stays blue no reducing sugar is present.

Question 29

What is the structure of glycogen?

Answer 29

Glycogen has a large number of side branches, similar to amylopectin’s structure

Question 30

What is the test for non-reducing sugar?

Answer 30

Add dilute hydrochloric acid to the test sample to hydrolyse the polysaccharides/disaccharides into its constituent monosaccharides. Then add sodium hydrogencarbonate to neutralise the acid.
Add sample to benedict’s reagent and then heat the sample.
If the solution turns brick-red then non-reducing sugar is present. If the solution stays blue then there’s no non-reducing or reducing sugar present.