3.1.2 Carbohydrates

Question 1

main functions of carbohydrates

Answer 1

Short term energy storage (ATP)
Long term energy storage
Building bonds

Question 2

What elements make up carbohydrates

Answer 2

Oxygen
Carbon
Hydrogen

Question 3

What does a monosaccharide mean?

Answer 3

Mono=one
Saccaride =sugar

Question 4

What is the name of the molecule when you combine 2 monosaccharides

Answer 4

Disaccharide

Question 5

What carbohydrate do you make when you combine many monosaccharides?

Answer 5

Polysaccharide

Question 6

Give examples of polysaccharides

Answer 6

Starch, glycogen , cellulose

Question 7

What class of carbohydrate is
A) soluble in water
B) sweet tasting

Answer 7

Monosaccharides and disaccharides
(Answer for both part A and B)

Question 8

What is the general formula for a monosaccharide

Answer 8

(CH2O)n

Question 9

What are the three monosaccharides?

Answer 9

Triose(3 carbons)
Penrose (5 carbons)
Hexose (6 carbons)

Question 10

Draw hexose

Answer 10

H O
\ //
H-C-OH
|
HO-C-H
|
H-C-OH
|
H-C-OH
|
CH2OH

Question 11

What the different between alpha and beta glucose ?

Answer 11

On alpha the OH on the 1st carbon is down

Question 12

Draw beta glucose

Question 13

Define isomer

Answer 13

Molecules that have the same chemical formula but different structural formula

Question 14

How is a disaccharide formed?

Answer 14

2 monosaccharides joined by covalent bonds-condensation reaction

Question 15

What is a condensation reaction?

Answer 15

Water being a product

Question 16

How to form maltose?

Answer 16

Alpha glucose + alpha glucose = maltose + H2O
G2 Manky

Question 17

How to make lactose ?

Answer 17

Alpha glucose + galactose = lactose + h2O
(GGL)

Question 18

How to make sucrose?

Answer 18

Alpha glucose + fructose = sucrose + H2O
(GFS)

Question 19

What is a hydrolysis reaction?

Answer 19

Water inserted into a disaccharide to split it into 2 monosaccharides

Question 20

Formula for disaccharides

Answer 20

Cn(H2O)n-1

Question 21

What are reducing sugars? And what are they called reducing?

Answer 21

A)All monosaccharides and disaccharides

B) they will gain an electron (oil RIG)-
Reduction of charge Is Gain of electron

Question 22

Method for testing for reducing sugars

Answer 22

1) add Benedict’s reagent to about 2 cm3 of test solution
2) shake and heat for a few minutes in 95oC in a water bath
3) a precipitate forms

Question 23

What are the results in reducing sugars test?

Answer 23

0%= blue(sucrose)
0.5%=green
1%= yellow
2%=BRICK RED

Question 24

Is Benedict’s test quantitative or qualitative?

Answer 24

Qualitative (interpretation based)

Question 25

Method to test for non-reducing sugars

Answer 25

1)Test for reducing sugars - if negative continue with method below
2) and 2cm3 dilute hydrochloric acid to 2cm3 of the sample solution and boil for a few minutes to hydrolyse the glycosidic bond
3) add sodium hydrogen carbonate solution to neutralise the hydrochloric acid
4)re test with Benedict’s reagent
5) if non reducing sugar present then original solution will change color

Question 26

What is a polysaccharide?

Answer 26

Many monosaccharides bonded together

Question 27

What are the 2 types of polysaccharides?

Answer 27

1) storage-starch and glycogen
2) structural- cellulose

Question 28

What is the role of starch?

Answer 28

It’s an insoluble store of glucose in plants

Question 29

What makes starch?

Answer 29

2 glucose polymers - amylose and amylopectin

Question 30

What bond and molecule makes amylose?

Answer 30

1,4 glycosidic bonds and alpha glucose

Question 31

What is the shape of amylose?
How is it formed?
Why is this beneficial ?

Answer 31

1) coils into a helix
2) formed by the angle of glycosidic bonds - hydrogen bonds help hold the stricter in place
3) its compact and can store a lot(of amylopectin)

Question 32

What formed amylopectin?
What are the bonds?

Answer 32

Alpha glucose

1,4 and some 1,6 glycosidic bonds (every 25 units)

Question 33

Why is the strictest of starch beneficial?

Answer 33

1) compact shape - a lot can be stored in a little
2)insoluble - dosent affect water potential
3) easily hydrolysed- to alpha glucose for respiration
4) branched form- means that enzymes can act in multiple ends at the same time meaning it’s quick for the glucose monomer to be released

Question 34

Method to test for starch

Answer 34

Put 2cm3 of iodine on test subject
If positive test subject turns a blue/black

Question 35

Where is glycogen found and what does it store?

Answer 35

In animals and bacteria-in animals it is stored as small grains mainly in the muscles and the liver

Question 36

What forms glycogen?
Bonds

Answer 36

Alpha glucose
1,4 and 1,6 glycosidic bonds

Question 37

Function to structure with glycogen

Answer 37

1)compact shape
2)insoluble
3) easily hydrolysed
4) the speed of hydrolysis if important- it has more branches than starch so it’s quicker

Question 38

What forms cellulose?
Bonds?

Answer 38

Beta glucose
1,4 glycosidic bonds

Question 39

Why is every 2nd glucose flipped 180 degrees in cellulose

Answer 39

To form the oxygen bridge for the condensation reaction

Question 40

Structer of cellulose?

Answer 40

Long unbranched parallel chains boned with hydrogen bonds

Question 41

Description of cellulose

Answer 41

Cellulose molecules become tightly cross linked to form bundles (microfibrils) these join together to form macrofibril which bundle to form cellulose fibres. The cell wall has multiple fibres in different directions which increases strength
Microfibrills are very strong and rigid to give huge structural stability to the cell