Biological molecules spec

Question 1

what are carbohydrates used for

Answer 1

respiritory substrates
structural components in plasma cells and cell walls

Question 2

what are lipids used for

Answer 2

bilayer of plasma membranes
hormones as respiritory substrates

Question 3

what are proteins used for

Answer 3

enzymes
chemical messangers
components in the blood

Question 4

what do nucleic acids do

Answer 4

carry the genetic code for the production of protiens

Question 5

what is a monomer

Answer 5

smaller units from
which larger molecules are made

Question 6

what is a polymer

Answer 6

molecules made from a large number of monomers joined together by a condensation reaction

Question 7

example of monomers

Answer 7

monosaccharides
amino acid
nucleotides

Question 8

condensation reaction

Answer 8

joins to molecules together with the formation of a chemical bond involving the elimination of a molecule of water

Question 9

hydrolysis reaction

Answer 9

breaks a chemical bond between two molecules and lnvolves the use of a water molecule

Question 10

what is a monosaccharide

Answer 10

monomer from which larger carbohydrates are made
sweet tasting soluble substances
e.g glucose, galactose, fructose

Question 11

what is a glycosidic bond

Answer 11

a condensation reaction between two monosaccharides

Question 12

when are disaccharides formed

Answer 12

a condensation reaction between two monosaccharides

Question 13

how is the disaccharide maltose formed

Answer 13

condensation reaction between 2 glucose molecules

Question 14

how is the disaccharide sucrose formed

Answer 14

condensation reaction between glucose and fructose

Question 15

how is the disaccharide lactose formed

Answer 15

condensation reaction of a glucose and galactose molecule

Question 16

what are the 2 isomers of glucose

Answer 16

alpha glucose
beta glucose

Question 17

how is alpha glucose formed

Answer 17

condensation reaction of glycogen and starch

Question 18

how is beta glucose formed

Answer 18

condensation reaction of beta glucose

Question 19

what is a reducing sugar

Answer 19

a sugar that can donate electrons to another chemical
e.g all monosaccharides and some disaccharides

Question 20

what is the test for reducing sugars

Answer 20

Benedicts test

Question 21

how does the benedicts test work

Answer 21

it is a alkaline sugar that when a reducing sugar is heated with benedicts solution it forms a orange brown precipitate

Question 22

what is a non-reducing sugar

Answer 22

a sugar that does not change the colour of benedicts regent when heated with it

Question 23

how to detect/test a non-reducing sugar

Answer 23

first hydrolyse into its monosaccharides by hydrolysis by:
ccompleting the benedicts regeant test for reducing sugar
then add a dilute hydrochloric acid into a test tube add to a water bath- it will hydrolyse any disaccharide present into its monosaccharides
then add sodium hydrocarbonate solution to neutralise the hydrochloric acid
then retest the solution with the benedicts solution in a water bath
if a non-reducing sugar was present in the original sample the benedicts solution will now turn orange brown in colour

Question 24

what is a polysaccharide

Answer 24

polymers formed by combining together many monosaccharide molecules
they are joined by glycocidic bonds from condensation reactions

Question 25

what are polysaccharides useful for

Answer 25

they are insoluble so they are good for storage some provide structural support in plants

Question 26

what is the test for starch

Answer 26

iodine test

Question 27

how to carry out the iodine test for starch

Answer 27

add the sample to a test tube add 2 drops of iodidne on to the sample in the presence of starch the sample will turn a blue-black colour

Question 28

starch

Answer 28

a polysaccharide found in plants- grains important coponent in food- major energy source made up of chains of alpha glucose joined by glycosidic bonds in a condensation reaction chains can be branched and unbranched

Question 29

how is the structure of starch useful 5 marker TAT

Answer 29

- insoluble so doesnt effect the water potential- water isnt drawn in by osmosis - large and insoluble so doesnt diffuse out of a cell - compact, so a lot can be stored in a small space - when hydrolysed it forms alpha glucose used in respiration - branched has many ends- glucose monomers can be eailt released

Question 30

glycogen

Answer 30

found in animal and bacteria cells never plants simillar structure to starch stored mainly in muscles

Question 31

glycogen features 5 marks

Answer 31

- insoluble doesnt draw water into the cell - insoluble so doesnt diffuse out of cells - compact lots stored in a small space - more highly branches than starch more ends that can be broken down to be used in respiraation humans have a higher metabolic rate so higher respiritory rate than plants as they are more active

Question 32

cellulose

Answer 32

made from monomers of beta glucose cellulose had straight unbranched chains running parrallel to one another- hydrogen forms cross links between adjacent chains

Question 33

cellulose structure 5 mark TAT

Answer 33

- long, straight, unbranded chain of beta glucose -joined by hydrogen bonds, -which form microfibrills -that provide strength and rigidity.