Carbohydrates

Question 1

What is the general formula for monosaccharides?

Answer 1

(CH2O)n

Where n = 3 to 7

Question 2

Where are carbohydrates used in living things?

Answer 2

As a source of energy for respiration

Storage

Question 3

What is the most common monosaccharide?

Answer 3

Hexoses

Question 4

What are some examples of monosaccharides?

Answer 4

Glucose
Fructose
Galactose
Ribose

Question 5

What are the types of glucose?

Answer 5

Alpha glucose

Beta glucose

Question 6

What rules are there for drawing alpha glucose?

Answer 6

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

Rule for the OH's 
Down 
Up 
Down 
Down

Question 7

Are all simple sugars reducing sugars?

Answer 7

No

Question 8

How do you test for reducing sugars?

Answer 8

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 9

What is a reducing sugar?

Answer 9

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 10

What helps to remember oxidation and reduction?

Answer 10

OIL RIG

Question 11

What reaction joins two monosaccharides together?

Answer 11

A condensation reaction

Question 12

What are two monosaccharides bonded called?

Answer 12

Disaccharides

Question 13

What is the bond called that holds the monosaccharides together?

Answer 13

Glycosidic

Question 14

What do you get when you react glucose + glucose?

Answer 14

Maltose

Question 15

What do you get when you react glucose + fructose?

Answer 15

Sucrose

Question 16

What do you get when you react glucose + galactose?

Answer 16

Lactose

Question 17

What happens in a condensation reaction?

Answer 17

A molecule of water is removed

Question 18

What is the reverse of a condensation reaction?

Answer 18

Hydrolysis

Question 19

How do you work out the formula of a disaccharide?

Answer 19

Add the two monosaccharides together and take away water

Question 20

What are the products of a condensation reaction?

Answer 20

A disaccharide and water

Question 21

How do you test for non-reducing sugars?

Answer 21

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 22

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

Answer 22

To split the disaccharides into monosaccharides using hydrolysis

Question 23

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

Answer 23

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

Question 24

What are the polymers we need to know?

Answer 24

Starch
Glycogen
Cellulose

Question 25

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

Answer 25

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

Question 26

What monomer and bonding is used to make starch?

Answer 26

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

Question 27

What are the coils held in place by in starch?

Answer 27

Hydrogen bonds

Question 28

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

Answer 28

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

Question 29

What are some properties of starch?

Answer 29

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 30

What is the test for starch?

Answer 30

Add iodine and a positive result is blue/black

Question 31

What is the monomer and bonding used in Glycogen?

Answer 31

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

Question 32

Where is glycogen found?

Answer 32

In animal cells as granules in muscle and liver cells

Question 33

What is the shape of glycogen?

Answer 33

Highly branched

Question 34

Where is cellulose found?

Answer 34

In plant cells in the cell wall

Question 35

How do the beta glucoses bond?

Answer 35

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

Question 36

What is the shape of cellulose?

Answer 36

Parallel chains

Question 37

What are the properties of cellulose?

Answer 37

Very strong Used for structural purposes Prevents cells bursting

Question 38

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

Answer 38

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 39

What are the properties of glycogen?

Answer 39

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

Question 40

What is a carbohydrate made up from?

Answer 40

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

Question 41

What is a polymer?

Answer 41

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

Question 42

What is a monomer?

Answer 42

A small single unit of an individual molecule

Question 43

What is the monomer of a carbohydrate called?

Answer 43

Saccharide

Question 44

What are simple monomers of carbohydrates called?

Answer 44

Monosaccharides

Question 45

In animals what are carbohydrates stored as? Where?

Answer 45

Glycogen in liver and muscles

Question 46

In plants what are carbohydrates used for? Where?

Answer 46

Starch - for storage | Cellulose - cell walls

Question 47

What is the formula for fructose?

Answer 47

C6H12O6