Biomolecules - Carbohydrates

Question 1

What are carbohydrates are made from?

Answer 1

Carbon, hydrogen and oxygen

Question 2

What do you two monosaccharides form?

Answer 2

A disaccharide

Question 3

What do you many monosaccharides form?

Answer 3

A polysaccharide

Question 4

What is the general formula formula monosaccharide?

Answer 4

(CH2O)n

Question 5

How many carbons does a triose sugar have?

Answer 5

3

Question 6

How many carbons does a pentose sugar have?

Answer 6

5

Question 7

How many carbons does a hexose sugar have?

Answer 7

6

Question 8

What type of sugar is it glucose molecule ?

Answer 8

A hexose sugar

Question 9

What is an isomer?

Answer 9

An isomer is when it has the same chemical formula but different structural formula e.g alpha and beta glucose

Question 10

Where is the OH group in the alpha glucose?

Answer 10

It is found below carbon one.

Question 11

Where is the OH group in the beta glucose?

Answer 11

It is found above carbon one.

Question 12

What happens in a condensation reaction?

Answer 12

Larger molecules are formed, a new covalent bond is formed and a water molecule is removed.

Question 13

What happens in a hydrolysis reaction?

Answer 13

Smaller molecules are formed, a covalent bond is broken and a water molecule is added.

Question 14

Alpha glucose + alpha glucose =

Answer 14

Maltose

Question 15

Alpha glucose + fructose =

Answer 15

Sucrose

Question 16

Alpha glucose + galactose =

Answer 16

Lactose

Question 17

Where is maltose found?

Answer 17

It is found in germinating seeds which is formed via a condensation reaction.

Question 18

Where is sucrose found?

Answer 18

It is transported in the phloem of flowering plants.

Question 19

Where is lactose found?

Answer 19

It is found in mammalian milk.

Question 20

What bond is formed in a condensation reaction?

Answer 20

A glycosidic bond.

Question 21

What are monosaccharides functions?

Answer 21

A source of energy in respiration, building blocks for larger molecules, intermediates and reactions, and constituents for nucleotides.

Question 22

What are carbohydrates functions?

Answer 22

Instant energy sources, transportable or storable forms of energy and structural materials.

Question 23

What are polysaccharides?

Answer 23

They are large complex polymers.

Question 24

How are polysaccharides formed?

Answer 24

They are formed by large numbers of monosaccharide units, the monomers which are linked by glycosidic bonds.

Question 25

What is the main store of glucose in plants?

Answer 25

Starch

Question 26

Why is starch the main store in plants?

Answer 26

It is insoluble so has no osmotic effect so it cannot diffuse out the cell. As it is a compact molecule it can be stored in small spaces and it carries a lot of energy between the C–H and C-C bonds.

Question 27

Why can't glucose be stored in plants?

Answer 27

It is soluble in water so the concentration of the cells contents would increase drawing water in by osmosis.

Question 28

What is the structure of amylose?

Answer 28

It is made from alpha glucose molecules, it is a branched linear molecule with alpha 1-4 glycosidic bonds between C1 on one glucose monomer and C4 on the other adjacent one this is repeated forming a chain which coils into a helix.

Question 29

What is the structure of amylopectin?

Answer 29

It has chains of alpha glucose monomers which are joined by alpha 1-4 glycosidic bonds. It cross links with alpha 1-6 glycosidic bonds and fits inside amylose. When a bond forms between C1 and the adjacent C6 a side branch is formed. Alpha glucose 1-4 glycosidic bonds continue from the start of the new branch.

Question 30

What is the main storage product in animals?

Answer 30

Glycogen

Question 31

What is the structure of glycogen?

Answer 31

It has alpha 1-4 and alpha 1-6 bonds, the glycogen molecules have shorter alpha 1-4 linked chains so are more branched than amylopectin.

Question 32

Where is cellulose found?

Answer 32

In a plant cell wall.

Question 33

What is the structure of cellulose?

Answer 33

It consists of long parallel chains of beta glucose units and beta 1-4 glycosidic bonds which join the molecules together. This beta link rotates the adjacent molecule 180° which allows hydrogen bonds to form between the OH groups on the adjacent parallel chain contributing to the stability of cellulose. Between 60 and 70 molecules become tightly crossed linked forming bundle is called microfibrils these are held in bundles called fibrils, where several layers of fibres run parallel within a layer but at an angle of the adjacent layer.

Question 34

What is a characteristic of the cell wall

Answer 34

It provides strength and support. Water and solutes can also penetrate through to the cell membrane as the cellulose fibres are freely permeable.

Question 35

Where is chitin found?

Answer 35

It is found in the exoskeleton of insects and in fungal cell walls.

Question 36

What is the structure of chitin?

Answer 36

It has long chains of beta glucose with 1-4 linked monomers but has groups derived from amino acid is added to form a heteropolysaccharide. The adjacent monomers are rotated 180° and they have long parallel chains which are cross-linked to each other by hydrogen bonds forming microfibrils. Chitin contains a nitrogen containing group - acetyl amine group.

Question 37

What are some properties of chitin?

Answer 37

It is strong, lightweight and waterproof.