Carbohydrates

Question 1

What is the product of condensation of 2 glucose molecules

Answer 1

Maltose and water

Question 2

What is the product of condensation of a glucose molecule and a fructose molecule

Answer 2

Sucrose and water

Question 3

Differences between glycogen and cellulose

Answer 3

Cellulose is from beta glucose and glycogen is from alpha glucose.
Cellulose is straight chain and glycogen is branched.
Cellulose has 1,4 glycosidic bond but glycogen has 1,4 and 1,6 glycosidic bond

Question 4

Starch is adapted to its function by being:

Answer 4

Insoluble - water is not drawn into the cell by osmosis.
Branched - more ends for enzyme action.
easily hydrolysed to glucose for respiration.
helical amylose - compact.
large - can’t cross cell membrane

Question 5

2 types of starch

Answer 5

amylose (linear and helical) and amylopectin (branched)

Question 6

what features of glycogen make it a useful storage molecule in muscle tissue?

Answer 6

highly branched so many ends so can be quickly hydrolysed into alpha glucose.

Question 7

differences between the structures of starch and glycogen

Answer 7

glycogen is more highly branched than amylopectin.
amylose is helical but glycogen is not.

Question 8

why does the liver continuously break down glycogen

Answer 8

to maintain blood glucose concentration

Question 9

how does cellulose being strong make it structurally well suited to its function in plant cells

Answer 9

gives cellulose cell walls strength which enables them to support the plant cell and maintain turgidity

Question 10

describe the structure of cellulose

Answer 10

cellulose is made of many beta glucose monomers with long and straight chains.
the chains line up parallel and are linked by many Hydrogen bonds.
many cellulose chains bind together to form a microfibril.
microfibrils bundle together to form macrofibrils.

Question 11

what happens to beta glucose in cellulose chains

Answer 11

every other beta glucose is upside down for alternate bonding which makes long and straight chains.

Question 12

Characteristics of starch

Answer 12

Made from many alpha glucose molecules.
polysaccharide.
branched (amylopectin)
Linear and helical (amylose)
1,4 and 1,6 glycosidic bonds (amylopectin).
Amylose has 1,4 glycosidic bonds.
Made from C, H, O.

Question 13

Glycogen characteristics

Answer 13

Made of many alpha glucose molecules. polysaccharide.
branched.
Coiled.
1,4 and 1,6 glycosidic bonds.
More branched than amylopectin.
Found/stored in skeletal muscle and tissue.

Question 14

Characteristics of cellulose

Answer 14

Made of many beta glucose molecules.
Straight and long chain.
1,4 glycosidic bonds.
Forms fibrils.
Polysaccharide.
Made from C, H, O.

Question 15

How to carry out a test for a reducing sugar

Answer 15

Add Benedict’s reagent to the sample.
Heat in hot water bath.
Colour change from blue to brick red precipitate.

Question 16

Describe test for non reducing sugar

Answer 16

Negative result: Benedict’s Reagent stays blue.
If sample is not liquid it must first be ground up in water.
Hydrolyse non reducing sugars into their monomers by adding HCL then heat in water bath.
Neutralise mixture by using sodium carbonate solution.
Then do Benedict’s test.
Positive result: will turn to red precipitate

Question 17

What happens in a condensation reaction

Answer 17

A chemical bond forms between 2 molecules and a molecule of water is produced.

Question 18

What happens in a hydrolysis reaction

Answer 18

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

Question 19

Cellulose is adapted to its function in plant cells by:

Answer 19

Having long and straight chains
Become linked by many H bonds to form fibrils
Provide strength to cell wall