carbohydrates

Question 1

What is a monomer

Answer 1

Small units which larger molecules are made

Question 2

What is a polymer

Answer 2

many monomers join together by a condensation reaction
E.g polysaccharides proteins DNA/RNA

Question 3

What is a condensation reaction

Answer 3

A chemical bond is formed between 2 molecules and it involves the elimination of a water molecule

Question 4

What is a hydrolysis reaction

Answer 4

A water molecule is used to break a chemical bond between 2 molecules

Question 5

What is a monosaccharide

Answer 5

Monomers which larger carbohydrates are made

Question 6

Give examples of monosaccharides

Answer 6

Glucose fructose galactose

Question 7

A condensation of 2 monosaccharides form a what

Answer 7

Glycosidic bond

Question 8

How is a disaccharide formed

Answer 8

2 monosaccharides joined together forming glycosidic bond

Formed by a condensation reaction, releasing a water molecule

Question 9

What is a polysaccharide

Answer 9

Formed by the condensation of many glucose units(many monosaccharides)
Joined together by glycosidic bond releasing water molecule

Question 10

How is glycogen and starch formed

Answer 10

By the condensation of alpha glucose

Question 11

Glucose + glucose

Answer 11

Maltose

Question 12

Glucose + fructose

Answer 12

Sucrose

Question 13

Glucose + galactose

Answer 13

Lactose

Question 14

Explain how the structures of starch relate to their functions

Answer 14

● Helical → compact for storage in cell
● Large, insoluble polysaccharide molecule → can’t leave cell membrane
● Insoluble in water → water potential of cell not affected

Question 15

Explain how the structure of glycogen relate to their function

Answer 15

● Branched → compact to fit more molecules in small area
● Branched → more ends for faster hydrolysis → release glucose for respiration to
make ATP for energy release
● Large, insoluble polysaccharide molecule → can’t leave cell membrane
● Insoluble in water → water potential of cell not affected

Question 16

Explain how the structure of cellulose relates to its function

Answer 16

● Every other β-glucose molecule is inverted in a long, straight, unbranched chain
● Many hydrogen bonds link parallel strands to form microfibrils (strong fibres)
● Hydrogen bonds are strong in high numbers
● So provides strength to plant cell walls

Question 17

What’s the Benedict’s test for reducing sugars

Answer 17

-add Benedict’s reagent to a sample and heat in water bath
-if positive it turns blue to red precipitate

Question 18

What is the test for non reducing sugars

Answer 18

1. Do Benedict’s test and stays blue / negative
2. Heat in a boiling water bath with acid (to hydrolyse into reducing sugars)
3. Neutralise with alkali
4. Heat in a boiling water bath with Benedict’s solution
5. Positive result = red precipitate

Question 19

Describe the biochemical test for starch

Answer 19

Add iodine
Positive result is a colour change orange to blue-black

Question 20

Describe the basic structure of starch

Answer 20

● Polysaccharide of α-glucose
● Amylose - 1,4-glycosidic bonds → unbranched
● Amylopectin - 1,4- and 1,6-glycosidic bonds → branched

Question 21

Describe the basic structure of cellulose

Answer 21

● Polysaccharide of β-glucose
● 1,4-glycosidic bond → straight, unbranched chains
● Chains linked in parallel by hydrogen bonds forming microfibrills

Question 22

Basic function of starch

Answer 22

Energy store in plant cells

Question 23

Basic function of cellulose

Answer 23

to strengthen cell wall of plant and algae cell wall

Question 24

basic function of glycogen

Answer 24

Energy store in animal cells

Question 25

Describe the structure of glycogen

Answer 25

● Polysaccharide made of α-glucose
● 1,4- and 1,6-glycosidic bonds → branched

Question 26

what are the 3 disaccharides

Answer 26

sucrose,maltose,lactose

Question 27

what are examples of monomers

Answer 27

glucose
nucleotides
amino acids

Question 28

what are examples of polymers

Answer 28

starch cellulose and glycogen
DNA/RNA
proteins

Question 29

Describe the difference between the structure of α-glucose and β-glucose

Answer 29

OH group is below carbon 1 in α-glucose but above carbon 1 in β-glucose

Alpha & beta glucose are isomers → differently arranged atom