monomers, polymers and monosaccahrides

Question 1

definition of monomer

Answer 1

the smaller units from which larger molecules are made

Question 2

definition of a polymer

Answer 2

molecules made from a large number of monomers joined together

Question 3

three examples of monomers

Answer 3

monosaccharides

amino acids

nucleotides

Question 4

what is a condensation reaction

Answer 4

a reaction that joins two molecules together

with the formation of a chemical bond

and involves the elimination of a molecule of water

Question 5

what is a hydrolysis reaction

Answer 5

a reaction that separates molecules

by breaking a chemical bond

and involves the use of a water molecule

Question 6

give the definition of a monosaccharide

Answer 6

the monomers from which larger carbohydrates are made

Question 7

name three common monosaccharides

Answer 7

glucose

galactose

fructose

Question 8

name the isomers of glucose

Answer 8

alpha-glucose and beta-glucose

Question 9

describe how disaccharides are formed

Answer 9

by a condensation reaction between two monosaccharides

Question 10

write the word equation for the formation of each disaccharide

Answer 10

glucose + glucose = maltose + water

glucose + fructose = sucrose + water

glucose + galactose = lactose + water

Question 11

describe the test for reducing sugars

Answer 11

add benedict’s reagent

heat

a positive result is a colour change from blue to green/yellow/orange/red

Question 12

suggest why the colour change occurs at the top of the test tube first

Answer 12

heat rises (convection currents)

the reaction occurs at the top of the test tube first

Question 13

describe the test for non-reducing sugars

Answer 13

following a negative reducing sugars test

boil the sample in acid (acid hydrolysis) - then add alkaline solution to neutralise

add benedict’s reagent and head

a positive result will go from blue to orange / red

Question 14

describe the test for starch

Answer 14

add iodine to the sample

a positive result will go from orange to blue / black

Question 15

describe the test for lipids

Answer 15

add ethanol and shake to dissolve

then add distilled water

a positive result is a white emulsion

Question 16

describe the test for proteins

Answer 16

add biuret reagent to the sample

a positive result will go from blue to purple

Question 17

starch - monomers

Answer 17

alpha glucose

Question 18

starch - which reaction and bonds join the monomers together

Answer 18

condensation

1,4 and 1,6 glycosidic bonds

Question 19

starch - state the function of the molecule

Answer 19

glucose store (energy source)

Question 20

starch - state where the molecule is found

Answer 20

starch grains in plant cells

Question 21

describe the structure of starch

Answer 21

starch is made up of amylose and amylopectin

amylose monomers are joined by 1,4 glycosidic bonds resulting in a spiral-shaped polymer

amylopectin monomers are joined by 1,4 and 1,6 glycosidic bonds

the 1,6 glycosidic bonds result in branches

Question 22

explain how the structure of starch related to function

Answer 22

starch is insoluble due to the fact is it a large molecule

it will not change the water potential of a cell and cause osmosis to occur

the spiral shape means that it can be readily compacted to store a lot

the branching strands provide a large surface area for enzymes to attach to increase hydrolysis

Question 23

name the monomers of glycogen

Answer 23

alpha glucose

Question 24

which reaction and bonds join the monomers of glycogen together

Answer 24

consensation

1,4 and 1,6 glycosidic bonds

Question 25

state the function of glycogen

Answer 25

glucose store - energy source

Question 26

describe the structure of glycogen

Answer 26

the key difference between the structure of glycogen and starch is that glycogen contains more 1,6 glycosidic bonds and is therefore more branched