1.2 Carbohydrates

Question 1

What is a monomer?

Answer 1

A small single unit of an individual molecule

Question 2

What is a polymer?

Answer 2

A larger molecule or a chain of many monomers linked together in condensation reactions

Question 3

What is metabolism?

Answer 3

All the chemical processes that take place in a living organism

Question 4

What is a carbohydrate made up from?

Answer 4

Carbon, hydrogen and Oxygen
With the ratio of -
Hydrogen:Oxygen
2:1

Question 5

Where are carbohydrates used in living things?

Answer 5

As a source of energy for respiration

Storage

Question 6

In animals what are carbohydrates stored as? Where?

Answer 6

Glycogen in liver and muscles

Question 7

In plants what are carbohydrates used for? Where?

Answer 7

Starch - for storage

Cellulose - cell walls

Question 8

What is the monomer of a carbohydrate called?

Answer 8

Saccharide

Posh word for sugar

Question 9

What are simple monomers of carbohydrates called?

Answer 9

Monosaccharides

Question 10

What is the general formula for monosaccharides?

Answer 10

(CH2O)n

Where n = 3 to 7

Question 11

What is the most common monosaccharide?

Answer 11

Hexoses

Question 12

What are some examples of monosaccharides?

Answer 12

Glucose
Fructose
Galactose
Ribose

Question 13

What are the types of glucose?

Answer 13

Alpha glucose

Beta glucose

Question 14

What rules are there for drawing alpha glucose?

Answer 14

Oxygen has to be bonded to the carbon not the hydrogen in OH

Rule for the OH's
Down
Up 
Down 
Down

Question 15

Are all simple sugars reducing sugars?

Answer 15

No

Question 16

How do you test for reducing sugars?

Answer 16

Add an equal volume of Benedict’s reagent to the sample
Heat the mixture for 3-5 mins
A brick-red precipitate indicates the presence of a reducing sugar

Question 17

What is a reducing sugar?

Answer 17

It has the power to reduce something else

The sugar itself loses electrons and oxidises but it reduces another substance that gains the electrons

Question 18

What helps to remember oxidation and reduction?

Answer 18

OIL RIG

Question 19

What reaction joins two monosaccharides together?

Answer 19

A condensation reaction

Question 20

What are two monosaccharides bonded called?

Answer 20

Disaccharides

Question 21

What is the bond called that holds the monosaccharides together?

Answer 21

Glycosidic

Question 22

What do you get when you react glucose + glucose?

Answer 22

Maltose

Question 23

What do you get when you react glucose + fructose?

Answer 23

Sucrose

Question 24

What do you get when you react glucose + galactose?

Answer 24

Lactose

Question 25

What happens in a condensation reaction?

Answer 25

A molecule of water is removed

Question 26

What is the reverse of a condensation reaction?

Answer 26

Hydrolysis

Question 27

How do you work out the formula of a disaccharide?

Answer 27

Add the two monosaccharides together and take away water

Question 28

What are the products of a condensation reaction?

Answer 28

A disaccharide and water

Question 29

How do you test for non-reducing sugars?

Answer 29

Add an equal volume of Benedict's Reagent to the sample and heat in a gently boiling water bath for 5 mins If it doesn't change colour a reducing sugar isn't present Then add equal volume of hydrochloric acid to the sample (different) Boil for 5 mins Slowly add sodium hydrogen carbonate solution Add Benedict's Reagent and if brick-red you know it is definitely a sugar present

Question 30

Why is hydrochloric acid used in the non-reducing sugars test?

Answer 30

To split the disaccharides into monosaccharides using hydrolysis

Question 31

Why is sodium hydrogen carbonate used in the non-reducing sugars test?

Answer 31

To change the pH as Benedict's Reagent only works in alkaline conditions

Question 32

What are the polysaccharides we need to know?

Answer 32

Starch Glycogen Cellulose

Question 33

What is starch primarily made of? Where is it found?

Answer 33

Amylose - a spiral shaped molecule Very little amylopectin In plants - as starch grains in chloroplasts

Question 34

What monomer and bonding is used to make starch?

Answer 34

Alpha Glucose is bonded by 1,4 glycosidic bonds that make stands before coiled

Question 35

What are the coils held in place by in starch?

Answer 35

Hydrogen bonds

Question 36

Why does the coiling make amylose suitable to be a storage molecule?

Answer 36

It is compact so allows a lot of Glucose in a small space

Question 37

What are some properties if starch?

Answer 37

Compact due to coiling Insoluble and not sweet Doesn't affect osmosis and doesn't diffuse out Hydrolysed from both ends to produce glucose

Question 38

What is the test for starch?

Answer 38

Add iodine solution and a positive result is blue/black

Question 40

What is the monomer and bonding used in Glycogen?

Answer 40

Alpa glucose is bonded by glycosidic bonds 1,4 and 1,6

Question 41

Where is glycogen found?

Answer 41

In animal cells as granules in muscle and liver cells

Question 42

What are the properties of glycogen?

Answer 42

Compact Insoluble They are hydrolysed much quicker than starch because of it's many ends

Question 43

What is the shape of glycogen?

Answer 43

Highly branched

Question 44

Where is cellulose found?

Answer 44

In plant cells in the cell wall

Question 46

How do the beta glucoses bond?

Answer 46

Carbon 6 alternates to allow the 2 OH groups to fit together to remove the water when every other glucose inverts

Question 47

What is the shape of cellulose?

Answer 47

Parallel chains | Cross linked with hydrogen bonds

Question 48

What is cellulose made from? What bonds and how is cellulose bonded?

Answer 48

Beta glucose joined by glycosidic bonds 1,4 The glucose's are able to be connected as every other glucose is reflected vertically There are thousands of weak hydrogen bonds which make it very strong called microfibril

Question 48

What are the properties of cellulose?

Answer 48

Very strong Used for structural purposes Prevents cells bursting as it exerts an inward pressure