carbohydrates

Question 1

elements in carbohydrates?

Answer 1

C H & O

Question 2

general formula of carbs?

Answer 2

Cn(H2O)n

Question 3

“monosaccharide” definition

Answer 3

single sugar / carb / saccharide unit

glucose , fructose , ribose

Question 4

“disaccharide” definition

Answer 4

when 2 monosaccharides join together

lactose , sucrose (fructose + glucose)

Question 5

“polysaccharide” definition

Answer 5

when 2+ monosaccharides join together to form a polymer

glycogen , cellulose , starch

Question 6

monosaccharide examples:

Answer 6

• glucose
• fructose
• ribose

Question 7

glucose formula?

Answer 7

C6H12O6

Question 8

what structure is glucose?

Answer 8

hexose monosaccharide (6 carbon hexose sugar)

Question 9

alpha glucose structure

Answer 9

carbon 1 to 6 up to down bonds:

H OH
H OH
OH H
H OH
CH2OH H
O

Question 10

beta glucose structure

Answer 10

carbon 1 to 6 up to down bonds:

OH H
H OH
OH H
H OH
CH2OH H
O

Question 11

is glucose polar and soluble and why?

Answer 11

polar + soluble in water bc H bonds between hydroxyl groups and water molecules

soluble = glucose dissolved in cytoplasm of the cell

Question 12

glucose condensation reaction?

Answer 12

1,4 glycosidic bond eliminating C1 OH and C4 OH + side product H2O

glucose —> disaccharide maltose

Question 13

hexose monosaccharide examples?

Answer 13

• glucose
• fructose (fruit)
• galactose

Question 14

glucose polymer?

Answer 14

glycogen

Question 15

maltose monomers?

Answer 15

a glucose + a glucose

Question 16

sucrose monomers?

Answer 16

a glucose + fructose

Question 17

lactose monomers?

Answer 17

b glucose + galactose

Question 18

“starch” ?

Answer 18

polysaccharide of a glucoses - chemical store of energy

Question 19

two types of starch molecules?

Answer 19

• amylose
• amylopectin

Question 20

amylose structure + characteristics?

Answer 20

• 1,4 glycosidic bonds
• bond angle = long glucose chain helix twist (stable by h bonds)
• more compact + less soluble

Question 21

benefits of amylose structure?

Answer 21

• more compact + less soluble

Question 22

amylopectin structure + characteristics?

Answer 22

• 1,4 glycosidic bonds a glucose molecules
• 1,6 glycosidic bonds every 25 glu molecules (condensation reactions)
• branched structure
• insoluble

Question 23

energy store in plants?

Answer 23

starch (amylose amylopectin)

Question 24

energy store in animals?

Answer 24

glycogen

Question 25

benefits of glycogen as an energy store?

Answer 25

- more branched than amylopectin = more compact + takes less storage space bc cooling + branching - branching = free ends for more glucose added b removed =quick process of storing / releasing glu molecules for cells

Question 26

key glucose + amylopectin properties?

Answer 26

- insoluble - branched - compact

Question 27

why is branching / coiling good?

Answer 27

- compact = less space used - branching = free ends = removal or additional of glu molecules = quick release / store of glucose

Question 28

“respiration”

Answer 28

process where biochemical energy in nutrients is converted into useable energy for organisms

Question 29

how does starch/glycogen release glucose?

Answer 29

hydrolysis breaking glycosidic bonds

Question 30

why can’t b glucose join like a glucose?

Answer 30

hydroxyl groups on C1 C4 too far away

Question 31

how can b glucose combine?

Answer 31

- flip one b glucose upside down - unable to coil or branch - straight chain “cellulose”

Question 32

cellulose monomers?

Answer 32

b glucose + b glucose

Question 33

disaccharide examples?

Answer 33

- sucrose - maltose

Question 34

polysaccharide examples?

Answer 34

- glycogen - cellulose - starch

Question 35

what does cellulose make up in humans?

Answer 35

cellulose —> microfibrils —> macrofibrils —> fibres —> cell walls (strong + insoluble)

Question 36

why is cellulose important for the diet?

Answer 36

hard to break down but forms fibre for healthy digestive system

Question 37

what are reducing sugars?

Answer 37

donate electrons / reduce the other molecule

Question 38

reducing sugar examples

Answer 38

ALL monosaccharides and SOME disaccharides (maltose lactose)

Question 39

non-reducing sugar examples

Answer 39

sucrose

Question 40

reducing sugar test name

Answer 40

Benedict’s test

Question 41

explain the reducing sugars test

Answer 41

Benedict’s test 1. place sample in boiling tube 2. add equal volume of Benedict’s reagent 3. heat mixture gently in water bath for 5 mins

Question 42

what is Benedict’s reagent?

Answer 42

alkaline copper II sulfate solution

Question 43

Benedict’s test results?

Answer 43

- red Cu2 react w copper ions = adds electrons to blue Cu2+ ions —> reduced to brick red Cu+ ions - red precipitate

Question 44

why is a red precipitate formed in Benedict’s yes for reducing sugars?

Answer 44

- sugars reduce Cu2+ blue ions —> red Cu+ ions - red precipitate more reducing sugars = more red precipitate

Question 45

reducing sugars test effect on non reducing:

Answer 45

- remains blue (blue —> green —> yellow —> orange —> red) = neg result

Question 46

how can sucrose give a positive result?

Answer 46

boil sucrose (DISACCHARIDE) in dilute HCl = hydrolysed to glucose or fructose (MONOSACCHARIDES) then gives pos result

Question 47

starch test name?

Answer 47

iodine test

Question 48

describe the starch test?

Answer 48

mix few drops of iodine dissolved in potassium iodide with solution yellow —> blue / black

Question 49

starch test results?

Answer 49

yellow / brown —> blue / black

Question 50

what are reagent strips used for?

Answer 50

to test for reducing sugars

Question 51

benefits of reagent strips?

Answer 51

use of a colour chart showing sugar concentration