Topic 1- Carbohydrates

Question 1

What elements do all carbohydrates contain?

Answer 1

Carbon, hydrogen and oxygen

Question 2

What ratio are Hydrogen and oxygen always in?

Answer 2

2:1

Question 3

What are the 3 types of carbohydrates

Answer 3

monosaccharides, disaccharides and polysaccharides

Question 4

Define monosaccharide

Answer 4

Single sugar monomer

Question 5

Define disaccharide

Answer 5

a sugar formed from 2 monosaccharides joined by a glyosidic bond in a condensation reaction

Question 6

Define polysaccharide

Answer 6

a polymer formed by many monosaccharides joined by glyosidic bonds in a condensation reaction

Question 7

Give 2 examples of monosaccharides

Answer 7

-Ribose (5c)
-Glucose (6c)

Question 8

Give 3 examples of disacharides

Answer 8

-Lactose (a glucose+ b galactose)
-Sucrose (a glucose + fructose)
-Maltose (a glucose + a glucose)

Question 9

Give 3 examples of polysacharides

Answer 9

-Cellulose (b glucose)
-Starch (a glucose in the form of amylose and amylopectin)

Question 10

What are the functions of monosaccharides?

Answer 10

-Source of energy in respiration
-Building blocks of polymers

Question 11

What are the functions of disaccharides?

Answer 11

-Sugar found in germinating seeds ( maltose)
-Mammal milk sugar (lactose)
-Sugar stored in sugar cane (sucrose)

Question 12

What are the functions of polysaccharides?

Answer 12

-Energy storage (plants- starch) (animals-glycogen)
-Structural- cell wall

Question 13

How are sugars classified a reducing or non reducing?

Answer 13

Whether they can donate electrons or not

Question 14

Which sugar can donate electrons?

Answer 14

-Reducing sugar
-the carbonyl group becomes oxidised

Question 15

Give some examples of reducing sugars

Answer 15

glucose, fructose and galactose

Question 16

Different 1._____ = Different properties

Answer 16

1.Structural formula

Question 17

OILRIG

Answer 17

Oxidation is loss, reduction is gain

Question 18

What is the molecular formula for glucose?

Answer 18

C6H12O6

Question 19

Why is glucose known as an isomer?

Answer 19

Glucose exists in two structurally different forms – alpha (α) glucose and beta (β) glucose

Question 20

ABBA

Answer 20

-Alpha is below (OH)
-Beta is above (OH)

Question 21

Do starch and glucose only contain alpha glucose?

Answer 21

Yes

Question 22

Does cellulose just contain beta glucose?

Answer 22

yes

Question 23

why are monosaccharides bonded to form disaccharides and polysaccharides?

Answer 23

to make them more suitable for transport, storage and to have less influence on a cell’s osmolarity

Question 24

Which reactions are glyosidic bonds formed by?

Answer 24

Condensation reaction

Question 25

On which part of the molecule do the glyosidic bonds form on?

Answer 25

On the hydroxyl group (-OH)

Question 26

Types of glyosidic bonds for Maltose,Sucrose,cellulose,amylose
and Amylopectin

Answer 26

-Maltose a 1-4
-Sucrose a 1-2
-cellulose b 1-4
-amylose a 1-4
-Amylopectin a 1-4 and 1-6

Question 27

When is the glyosidic bond broken?

Answer 27

During a hydrolysis reaction

Question 28

Why are starch and glycogen good storage molecules?

Answer 28

-Compact (so large quantities can be stored)
-Insoluble (so will have no osmotic effect, unlike glucose which would lower the water potential of a cell causing water to move into cells, plant cells would then have to have thicker cell walls, and animal cells would burst under the increased pressure

Question 29

Give some features of amolysose

Answer 29

-Unbranched helix-shaped chain with 1,4 glyosidic bonds between α-glucose molecules
-The helix shape enables it to be more compact and thus it is more resistant to digestion

Question 30

Give some features of amylopectin

Answer 30

-1,4 glyosidic bonds between α-glucose molecules but also 1,6 glyosidic bonds form between glucose molecules creating a branched molecule
-The branches result in many terminal glucose molecules that can be easily hydrolysed for use during cellular respiration or added to for storage

Question 31

What is glycogen

Answer 31

-A storage molecule in animals and fungi

Question 32

Where is glycogen most commonly found?

Answer 32

Muscles and the liver

Question 33

Is glycogen more or less branched than amylopectin?

Answer 33

More branched so more compact which helps animals store more

Question 34

Is cellulose a polysaccharide?

Answer 34

Yes

Question 35

Give some features of polysaccharides

Answer 35

Branched or unbranched
Folded (making the molecule compact which is ideal for storage, eg. starch and glycogen)
Straight (making the molecules suitable to construct cellular structures, eg. cellulose) or coiled
Polysaccharides are insoluble in water

Question 36

What is the structure of cellulose?

Answer 36

-Is a polymer consisting of long chains of β-glucose joined together by 1,4 glycosidic bonds?
-Due to the inversion (because it is an isomer (same molecular formula but different structure) of a glucose) of the β-glucose molecules many hydrogen bonds form between the long chains giving cellulose its strength

Question 37

What is the function of cellulose

Answer 37

-main structural component of cell walls due to its strength which is a result of the many hydrogen bonds found between the parallel chains of microfibrils
-The high tensile strength of cellulose allows it to be stretched without breaking which makes it possible for cell walls to withstand turgor pressure
-The cellulose fibres and other molecules (eg. lignin) found in the cell wall form a matrix which increases the strength of the cell walls
-The strengthened cell walls provide support to the plant
-Cellulose fibres are freely permeable which allows water and solutes to leave or reach the cell surface membrane
-As few organisms have the enzyme (cellulase) to hydrolyse cellulose it is a source of fibre