Biological Molecules: Carbohydrates

Question 1

What is a monosaccharide?

Answer 1

A monomer from which larger carbohydrates can be made.

Question 2

What is an isomer?

Answer 2

Molecules with the same molecular formula, but have different arrangements of their atoms

Question 3

Name three monosaccharides:

Answer 3

Galactose
Glucose
Fructose

Question 4

What is the difference between the structure of alpha-glucose and beta-glucose:

Answer 4

Alpha-glucose = OH group is on bottom
Beta-glucose = OH group is on top

Question 5

What are the two isomers of glucose?

Answer 5

Alpha glucose
Beta glucose

Question 6

What happens in a condensation reaction?

Answer 6

Two monomers bond at their OH/HO groups
Water (H20) is lost

Question 7

What is a disaccharide?

Answer 7

Two monosaccharides joined together.

Question 8

How are disaccharides formed?

Answer 8

In the condensation reaction of two monosaccharides

Question 9

Name three disaccharides:

Answer 9

Maltose
Lactose
Sucrose

Question 10

_______ + _______ = Maltose

Answer 10

Glucose + Glucose = Maltose

Question 11

_______ + _______ = Sucrose

Answer 11

Glucose + Fructose = Sucrose

Question 12

_______ + _______ = Lactose

Answer 12

Glucose + Galactose = Lactose

Question 13

What is the function of cellulose?

Answer 13

Provides rigidity and strength to plants cell wall.

Question 14

How does the structure of cellulose help its function?

Answer 14

• As cellulose molecules are unbranched, they are able to get close together.
• Hydrogen bonds are able to form between neighbouring chains
• As many hydrogen bonds are formed, cellulose is extremely strong.

Question 15

What is a cellulose microfibril?

Answer 15

Strong threads (made of long cellulose chains) that are parallel to one another, joined together by hydrogen bonds.

Question 16

What is a cellulose macrofibril?

Answer 16

Many straight cellulose microfibrils joined together.

Question 17

Give two ways in which the structure of starch is similar to the structure of cellulose?

Answer 17

Both have glycosidic bonds
Both have hydrogen bonds

Question 18

Give two ways in which the structure of starch is different to the structure of cellulose?

Answer 18

Starch is branched, cellulose isn’t
Starch contains alpha-glucose, cellulose contains beta-glucose

Question 19

What does benedict’s solution test for?

Answer 19

Sugars

Question 20

Why is glycogen and starch coiled?

Answer 20

So it is compact so more glycogen can fit in a smaller area.

Question 21

Why is glycogen and starch being large an advantage?

Answer 21

Means it can’t cross the cell membrane when it is stored in a cell.

Question 22

Why is glycogen and starch being insoluble an advantage?

Answer 22

Will not affect the water potential of a cells cytoplasm when it is stored inside a cell.

Question 23

What are the three features that make glycogen and starch good storage molecules:

Answer 23

Compact
Large
Insoluble

Question 24

Why are starch and glycogen good molecules for respiration?

Answer 24

They are coiled and highly branched
Enzymes have many ends for hydrolysing enzymes
Quicker for glucose molecules to be released

Question 25

What is a glycosidic bond?

Answer 25

A covalent bond formed between monosaccharides, resulting in a condensation reaction.

Question 26

In alpha glucose the OH group is at the _____.

Answer 26

Bottom

Question 27

In beta glucose the OH group is at the _____.

Answer 27

Top

Question 28

Describe the structure of amylose:

Answer 28

• Long
• unbranched chain
• A-glucose, 1-4 glycosidic bonds

Question 29

Polymerisation of alpha glucose can form ______ or _______.

Answer 29

Starch or glycogen.

Question 30

What are the two forms of starch?

Answer 30

• Amylose
• Amylopectin

Question 31

Why is amylose a good storage molecule for small spaces?

Answer 31

Angles of glycosidic bonds give it a coiled structure = can fit more in a small space.

Question 32

Why is amylopectin a good storage molecule for quick energy release?

Answer 32

Side branches allow enzymes to break down the molecule to get to the glycosidic bonds easily = quick glucose release.

Question 33

What does the polymerisation of alpha glucose produce?

Answer 33

Glycogen
Starch

Question 34

What does the polymerisation of beta glucose produce?

Answer 34

Cellulose

Question 35

Why doesn’t starch affect a cells water potential?

Answer 35

It is insoluble in water.

Question 36

What two polysaccharides is starch a mixture of?

Answer 36

Amylose
Amylopectin

Question 37

Animals store excess glucose as ________.

Answer 37

Glycogen

Question 38

Plants store excess glucose as ________.

Answer 38

Starch

Question 39

Describe the structure of glycogen:

Answer 39

• Long
• Very branched
• Made of alpha-glucose
• Compact

Question 40

Why is glycogen being very branched an advantage?

Answer 40

Stored glucose can be released quickly.

Question 41

Describe the structure of cellulose:

Answer 41

• Long
• Unbranched chains
• Beta-glucose, 1-4 glycosidic bonds

Question 42

Describe the structure of amylopectin:

Answer 42

• Long
• Branched
• Alpha glucose, 1-4 and 1-6 glycosidic bonds

Question 43

Cellulose chains are linked together by _________.

Answer 43

Hydrogen bonds.

Question 44

Cellulose chains are linked together by hydrogen bonds to form ______.

Answer 44

Microfibrils.

Question 45

Why are microfibrils important in a plant?

Answer 45

Provides structural support.

Question 46

A condensation reaction between two monosaccharides forms a ______ bond.

Answer 46

Glycosididic