Carbohydrates

Question 1

What is carbon’s unusual feature?

Answer 1

It readily forms bonds with other carbons

Question 2

Name the four main elements

Answer 2

Oxygen Nitrogen Carbon Hydrogen

Question 3

What is a monomer?

Answer 3

Small units from which larger units are made

Question 4

Name 3 examples of monomers

Answer 4

Monosaccharides amino acids and nucleotides

Question 5

What is a condensation reaction?

Answer 5

Joins 2 molecules together with the formation of a chemical bond and involves the elimination of a water molecule

Question 6

What is a hydrolysis reaction?

Answer 6

Breaks a chemical bond between 2 molecules and involves the use of a water molecule

Question 7

What is the monomer that makes up carbohydrates?

Answer 7

monosaccharides

Question 8

Name 3 common monosaccharides ?

Answer 8

Glucose
Fructose
Galactose

Question 9

Name the bond formed between two monosaccharides?

Answer 9

Glycosidic Bond

Question 10

Monosaccharide + Monosaccharide =

Answer 10

Disaccharide

Question 11

glucose + glucose =

Answer 11

maltose ( plus water !!)

Question 12

glucose + fructose

Answer 12

sucrose ( plus water !!)

Question 13

glucose + galactose

Answer 13

lactose ( plus water !!)

Question 14

Name the 2 isomers of glucoses and how they differ ?

Answer 14

Alpha and beta glucose (SEE CARD)

The H and OH are flipped on C1 of a beta molecule.

Question 15

Name the test from reducing sugars and how to perform it.

Answer 15

Benedict’s Tests
2cm2 of a food sample
2cm2 of the Benedict’s reagent
5 mins in boiling water bath

Question 16

Name the results of the Benedict’s test

Answer 16

blue copper sulphate is reduced to red copper oxide

blue-green-yellow-orange-red

Question 17

How to do test for non-reducing sugars?

Answer 17

no colour change seen during the benedicts test
must hydrolyse into monosaccharides
2cm2 food sample + 2cm2 HCl } 5mins in boiling water bath
add sodium hydrogencarbonate ] to neutrilise, use pH paper to test
redo Benedict’s test

Question 18

What type of glucose are these made from?

Starch
Cellulose
Glycogen

Answer 18

Alpha glucose = starch and glycogen

Beta glucose = cellulose

Question 19

What is the main role of starch?

Answer 19

energy storage

Question 20

How is the structure of starch suited to its role?

Answer 20

Insoluble/ doesn’t affect water potential = water not drawn into cell via osmosis
large and insoluble = doesn’t diffuse out of cells
COILED / helix shape compact = lots can be stored in a small space
when hydrolysed it forms alpha glucose which is easily transported and readily used in respiration
branched form has many ends so can be broken down quicker by enzymes.

Question 21

What is the difference between amylose and amylosepectin?

Answer 21

Amylopectin = branched polysaccharide ( α-1,4- and α-1,6-glycosidic bonds)
Amylose is a linear polysaccharide ( α-1,4-glycosidic bonds)
Amylose is rigid than amylopectin.
Amylose is less readily digested than amylopectin.

Question 22

What type of glycosidic bonds are in
Starch
Glycogen
Cellulose

Answer 22

1-4 and 1-6 = starch and glycogen

1-4 = cellulose

Question 23

How is the structure of glycogen suited to its role?

Answer 23

Insoluble/ doesn’t affect water potential = water not drawn into cell via osmosis
large and insoluble = doesn’t diffuse out of cells
compact = lots can be stored in a small space
highly branched = more ends for enzyme

Question 24

Why is glycogen only found in animal cells?

Answer 24

Animals have a higher metabolic rate hence a higher respiratory rate .

Question 25

Compare glycogen to starch

Answer 25

glycogen is shorter and more branched

Question 26

What is the role of glycogen ?

Answer 26

Energy store and maintain stable blood glucose

Question 27

Describe the structure of cellulose

Answer 27

straight unbranched chains
parallel so H bonds form cross linkages 
H bond =weak H bonds= strong
adjacent glucose rotate 180 ( OH on both sides) 
microfibre } fibres

Question 28

What is the function of cellulose?

Answer 28

adds rigidity to cells and exerts inward pressure to ensure no further influx of water.

Question 29

What is an organic molecule?

Answer 29

contains carbon

Question 30

What are reducing sugars?

Answer 30

sugars donate electrons to other chemicals

Question 31

Describe the starch test

Answer 31

add drops of iodine
shake
blue black if starch present

Question 32

Name the method to create sucrose solutions

Answer 32

dilution series