Unit 2 - Module 1 - Carbohydrates

Question 0

What percentage do they make up in a cell?

Answer 0

10%

Question 1

What are the functions?

Answer 1

Energy source - released from glucose during respiration
Energy store - e.g. starch
Structure - e.g. cellulose

Question 2

What is the general formula?

Answer 2

Cn(H2O)n

Question 3

What are the similar properties of monosaccharides?

Answer 3

Soluble in water
Sweet tasting
Form crystals

Question 4

What are 3-carbon monosaccharides called?

Answer 4

Triose sugars

Question 5

What are 5 carbon monosaccharides called?

Answer 5

Pentose sugars

Question 6

What are 6-carbon monosaccharides called?

Answer 6

Hexose sugars

Question 7

What are the two forms of glucose in the ring structure?

Answer 7

Alpha-glucose: H is above C1 and OH is below.

Beta-glucose: H is below C1 and OH is above.

Question 8

What is the name of the bond that forms between two monosaccharides?

Answer 8

Glycosidic bond

Question 9

What type of glucose can animals and plants break down? Why?

Answer 9

Alpha- glucose. They don’t have the enzyme that is complementary to beta-glucose.

Question 10

How can glucose be used in respiration?

Answer 10

It is broken down into smaller molecules, which releases energy which can be used to make ATP. Beta-glucose cannot be respired, as no enzymes.

Question 11

What disaccharide is formed from two alpha-glucose molecules?

Answer 11

Maltose

Question 12

What is formed when many alpha-glucose molecules are joined together?

Answer 12

Amylose

Question 13

What is the specific name of the bond in amylose?

Answer 13

1,4-glycosidic bond

Question 14

What do long chains of amylose form? Why?

Answer 14

They coil into a spring because of the shape of the glucose and the formation of the glycosidic bonds.

Question 15

What is the basis of the starch test?

Answer 15

Iodine molecules can become trapped in the coils of the spring. This cause the iodine to change colour from yellow/brown to blue-black.

Question 16

What is starch used for?

Answer 16

It is the energy-storage polysaccharide in plants.

Question 17

What does starch consist of?

Answer 17

A mixture of long, straight-chain amylose molecules and pranced amylopectin.

Question 18

Where is starch stored?

Answer 18

In chloroplasts and elsewhere in the plant in membrane bound starch grains. Cells of storage organs contain a lot of starch grains.

Question 19

Why is starch important?

Answer 19

It can be stored as it insoluble.

Can be broken down to glucose molecules, why may then be respired.

Question 20

What is glycogen?

Answer 20

It the energy-storage polysaccharide in animals.

Question 21

How does glycogen differ from starch?

Answer 21

The 1-4 linked glucose chains tend to be shorter and have many more branches.

Question 22

What does the short chains and branching in glycogen mean?

Answer 22

It is more compact than starch, and forms glycogen granules - especially in live and muscle cells.

Question 23

Why is it important that energy storgae molecules are insoluble?

Answer 23

So they don’t affect water potential of cell. This is vital in plants and animals.

Question 24

Other than being insoluble why are energy storage molecule important?

Answer 24

Hold glucose molecules in chains so they can be easily ‘broken off’ from ends to provide glucose for respiration.

Question 25

What is the most abundant polysaccharide in nature?

Answer 25

Cellulose

Question 26

What can beta-glucose molecules form?

Answer 26

They form long and straight chains with 1,6-glycosidic bonds. Beta-glucose chains are called cellulose chains. They can be 10,000 molecules.

Question 27

How are cellulose fibres arranged in cell walls?

Answer 27

Cellulose chains hydrogen bond to form cellulose molecules.
Hydrogen bonds form between 60-70 molecules to form microfibrils.
Hydrogen bonds between microfibrils to form macrofibrils.

Question 28

What is the function of the cell wall?

Answer 28

Give great strength to each cell, supporting the whole plant.

Question 29

What are cell wall formed from?

Answer 29

Macrofibrils that are embedded in pectins

Question 30

What are the names, characteristics and roles of some monosaccharides?

Answer 30

Glucose. Small, soluble, sweet and crystalline. Provides energy via respiration.
Deoxyribose. Part of DNA- information molecule.

Question 31

What is the name, characteristics and role of a disaccharide?

Answer 31

Maltose.
Small, sweet, soluble and crystalline.
A sugar obtained when starch is broken down in hydrolysis reaction. Can be split further to glucose.