-1A: carbohydrates

Question 1

define monomer:

Answer 1

repeating units from which polymers are made

Question 2

define polymer:

Answer 2

made from lots of monomers bonded together

Question 3

what are the 3 main monomers to polymers in biology?

Answer 3

glucose -> starch, cellulose, glycogen
amino acids -> proteins
nucleotides -> DNA + RNA

Question 4

what elements do all carbohydrates contain?

Answer 4

carbon, hydrogen, oxygen

Question 5

what are the 3 classes?

Answer 5

-monosaccharides
-disaccharides
-polysaccharides

Question 6

what is the main monosaccharide?

Answer 6

glucose

Question 7

what are the two isomers of glucose + whats the difference between them?

Answer 7

-alpha + beta
-hydroxyl group of C1 is flipped at the top for B glucose

Question 8

draw the structure of both alpha + beta glucose

Question 9

what are the 3 monosaccharides?

Answer 9

-glucose
-fructose
-galactose

Question 10

define disaccharide:

Answer 10

-two monosaccharides
-joined together by a glycosidic bond
-via a condensation reaction

Question 11

what are the 3 disaccharides?

Answer 11

-sucrose
-maltose
-lactose

Question 12

word equation: sucrose?

Answer 12

glucose + fructose -> sucrose + water

Question 13

word equation: lactose?

Answer 13

glucose + galactose -> lactose + water

Question 14

word equation: maltose?

Answer 14

glucose + glucose -> maltose + water

Question 15

what are the two main reactions in biology, define them:

Answer 15

-condensation: joins monomers together which forms a chemical bond and releases water
-hydrolysis (reversal): breaking a chemical bond between monomers through the addition of water

Question 16

give an example of one of where polymers are hydrolysed into monomers in the body?

Answer 16

during digestion, starch -> glucose

Question 17

what catalyses the hydrolysis reactions?

Answer 17

enzymes

Question 18

define polysaccharide:

Answer 18

-two/more monosaccharides
-joined together by glycosidic bonds
-via condensation reactions

Question 19

what are the 3 polysaccharides?

Answer 19

-starch
-cellulose
-glycogen

Question 20

function of starch?

Answer 20

insoluble store of glucose

Question 21

what is starch made from?

Answer 21

-2 polymers of a glucose
-amylose + amylopectin

Question 22

amylose?

Answer 22

-formed through condensation reaction -> 1-4 glycosidic bonds
-straight, unbranched helix -> compact, store large amount of glucose

Question 23

amylopectin?

Answer 23

-formed through condensation reactions -> 1-4 + 1-6 glycosidic bonds
-branched molecule -> easily compacted to store large amount of glucose

Question 24

glycogen function?

Answer 24

insoluble store of glucose

Question 25

what is glycogen made from?

Answer 25

-condensation reactions -> 1-4 + 1-6 glycosidic bonds -more 1-6 glycosidic bonds -> highly branched molecule

Question 26

cellulose function?

Answer 26

provides structural strength to plant cell wall

Question 27

what is cellulose made from?

Answer 27

-condensation reactions between B glucose -> 1-4 glycosidic bonds -long straight chains lie parallel together, held by hydrogen bonds to form fibrils

Question 28

how does starch's structure lead to its function?

Answer 28

-helix = compact -> fit a lot of glucose into one place -branched structure increases s:a for rapid hydrolysis back to glucose -insoluble -> wont affect water potential

Question 29

how does glycogens structure lead to its function?

Answer 29

-branched structure increases s:a for rapid hydrolysis back to glucose -insoluble -> wont affect water potential

Question 30

how does celluloses structure lead to its function?

Answer 30

-many hydrogen bonds provide collective strength -insoluble -> wont affect water potential

Question 31

a student carried out a benedicts test. suggest a method, other than a colorimeter, that this student could use to measure the quantity of reducing sugar in a solution

Answer 31

-filter + dry the precipitate -find weight/mass

Question 32

use of a colorimeter in this investigation would improve the repeatability of the students results, give one reason why

Answer 32

-quantitative -standardises the method

Question 33

in test 1, the student used a measuring culinder to measure 15cm3 of solution from a beaker. the measuring cylinder gives a volume with an uncertainty of +/- 1cm3. she used a graduated syringe to measure 5.0cm3 of benedicts solution. the graduated syringe gives a volume with an uncertainty of +/- 0.5cm3. she mixed these volumes of liquid to do the biochemical test. calculate the percentage error for the measurements used to obtain a 20 cm3 mixture of the solution from the beaker and benedicts solution. show your working

Answer 33

1/150 + 0.5.5 x 100 16.7-17

Question 34

what test would show the presence of starch?

Answer 34

iodine/potassium iodide test

Question 35

describe the structure of glycogen

Answer 35

-polymer of a glucose -branched

Question 36

explain how you would use the graph to determine the maltose concentration with a light absorbance of 0.45 arbitrary units

Answer 36

-draw a line of best fit -read off value of 0.45

Question 37

difference between alpha and beta glucose?

Answer 37

position of hydrogen and hydroxyl group on C1 = inverted

Question 38

what is meant by the term 'sugars'?

Answer 38

all monosaccharides + disaccharides

Question 39

what can sugars be classed into?

Answer 39

-reducing -non-reducing

Question 40

what are reducing sugars?

Answer 40

-all monosaccharides -lactose + maltose

Question 41

example of non-reducing sugar?

Answer 41

sucrose

Question 42

describe how you would test for reducing sugars in a food sample

Answer 42

-add benedicts reagent (blue) -heat - in water bath that's been bought to boil -positive result = coloured precipitate (blue -> green -> yellow -> orange -> red)

Question 43

what is the concentration of reducing sugars determined by, and what can this be used for?

Answer 43

-how far along the colour change is -used to compare concentrations of reducing sugars between different solutions

Question 44

what is the concentration of reducing sugars determined by, and what can this be used for?

Answer 44

-how far along the colour change is -used to compare concentrations of reducing sugars between different solutions

Question 45

describe the test used for non-reducing sugars

Answer 45

-new sample of test solution (-negative result from reducing sugars test) -add dilute HCL + heat in water bath that's been bought to boil -add sodium carbonate - to neutralise -carry out benedict's test

Question 46

why do you add dilute HCL to the sample in test for non-reducing sugars?

Answer 46

to break it down into its monosaccharides

Question 47

why do we use an excess of benedict's reagent?

Answer 47

to ensure all of the sugar reacts

Question 48

describe how a molecule of maltose is formed:

Answer 48

-condensation reactions between two a glucose molecules -releasing a molecule of water -forming a glycosidic bond

Question 49

why is _____ described as a polysaccharide?

Answer 49

because its made up of chains of monosaccharides

Question 50

when describing a specific hydrolysis reaction, what should you always try to do?

Answer 50

name bond being broken

Question 51

some organisms are able to make their own chitinases, explain how it would be beneficial for plants to make + secrete chitinases as a defense system

Answer 51

-secretion of chitinases would protect plants against attack by insects -fungus infection by breaking down chitin in the exoskeleton of insects + cell walls of fungi -which would kill invading organisms