Mononomers + carbohydrates

Question 1

Where is a glycosidic bond used

Answer 1

To join together glucose

Question 2

How can starch be tested for ?

Answer 2

-add iodine dissolved in potassium iodide solution.
- if there is a starch present, the sample changes from browny-orange to a dark blue-black colour

Question 3

When is a polysaccharide formed ?

Answer 3

Condensation of many glucose units

Question 4

Describe a test for non-reducing sugar?

Answer 4

-Add dilute hydrochloric acid to the sample
-Heat in a water bath that has been brought to the boil
-Neutralise the solution with sodium hydrogencarbonate
-carry out benedicts test as normal

Question 5

Example of non-reducing sugar?

Answer 5

Sucrose

Question 6

4 reducing sugars

Answer 6

Galactose, fructose, glucose and maltose

Question 7

How test for reducing sugar ?

Answer 7

-Add benedicts reagent to a sample and heat it in a water bath that has been brought to a boil
-Positive = form a coloured ppt from blue to red ( lowest conc. to highest )

Question 8

How can you compare the results of a test for reducing sugars ?

Answer 8

-Compare the colour change (blue to red )
-Filter and weigh the precipitate

Question 8

How can you compare the results of a test for reducing sugars ?

Answer 8

-Compare the colour change (blue to red )
-Filter and weigh the precipitate

Question 9

How is the structure of glycogen related to its function? (4)

Answer 9

-Branched, so compact for storage
-Insoluble, so does not effect water potential of cells it is stored in
-Branched structure, so more ends for faster hydrolysis
-Contains glucose, so provides respiratory substrate

Question 9

Briefly describe the diagrams of the polymers; cellulose, starch and glycogen.

Answer 9

Starch:
-amylopectin = branched
-amylose = unbranched coil/helix
-Cellulose would be in straght, unbranched rows
-glycogen - branched

Question 9

How does the structure of starch help to fulfill its function?

Answer 9

-amylose is coiled/helix, so compact
-amylopectin is branched, so more ends for faster hydrolysis
-insoluble, does not effect water potential of cells it is stored in
-Contains glucose, so provides respiratory substrate

Question 10

What is starch made up of (what two polysaccharides)?

Answer 10

2 different polysaccharides- amylose, amylopectin

Question 11

Which monomers of glucose are; starch, glycogen, cellulose

Answer 11

starch-alpha
glycogen-alpha
cellulose-beta
remember as: walls are for betas, live outisde

Question 11

How is starch formed

Answer 11

Condensation of a glucose

Question 12

How is cellulose formed

Answer 12

condensation of b glucose

Question 13

how is glycogen formed

Answer 13

condensation of a glucose

Question 14

what are a and b glucose ?

Answer 14

isomers of glucose

Question 15

How are dissacharides formed

Answer 15

Disaccharides are formed by the condensation of two monosaccharides

Question 16

lactose is a __ formed by condensation of __

Answer 16

lactose is a disaccharide formed by condensation of a glucose molecule and a galactose molecule.

Question 17

sucrose is a __ formed by condensation of __

Answer 17

sucrose is a disaccharide formed by condensation of a glucose molecule and a fructose molecule

Question 18

maltose is a __ formed by condensation of __

Answer 18

maltose is a disaccharide formed by condensation of two glucose molecules

Question 19

what are monosaccharides?

Answer 19

Monosaccharides are the monomers from which larger carbohydrates are made

Question 20

What are polymers

Answer 20

Polymers are molecules made from a large number of monomers joined together.

Question 21

Describe a condensation reaction.

Answer 21

-Joins two molecules together with the formation of a chemical bond
-Involves the elimination of a molecule of water.

Question 22

Describe a hydrolysis reaction

Answer 22

-Breaks a chemical bond between two molecules
-Involves the use of a water molecule.

Question 23

Describe how the structure of cellulose is related to its function(3)

Answer 23

-cellulose molecules are made up of b-glucose and so form long, unbranched chains
-cellulose molecular chains run parralell to each other and are cross linked by H bonds which add a collective strenght
-these molecules are grouped to form microfibriles which in turn are grouped to form fibres all of which provide more strenght