chapter 3 - biological molecules

Question 1

what are the three main single sugars / monosaccharides?

Answer 1

1. glucose
2. galactose
3. fructose

“great girl friends”

Question 2

what are the three main double sugars / disaccharides?

Answer 2

1. Maltose = glucose + glucose
2. lactose = glucose + galactose
3. sucrose = glucose + fructose

Question 3

maltose = glucose + _____________

Answer 3

glucose

Question 4

lactose = glucose + _____________

Answer 4

galactose

Question 5

why do we need food?

Answer 5

the nutrients in the food provide us with energy and materials needed by the body

Question 6

sucrose = glucose + _____________

Answer 6

fructose

Question 7

galactose is commonly found in _____________

Answer 7

milk from mammals

Question 8

glucose is commonly found in ______________

Answer 8

plants and animals

Question 9

fructose is commonly found in ___________

Answer 9

plants
(very rare in animals)

Question 10

what is the test for reducing sugars?

Answer 10

Benedict’s test (using benedict’s solution)

Question 11

what are the reducing sugars?

Answer 11

1. glucose
2. galactose
3. fructose
4. lactose
5. maltose
   “great girl friends like me”

Question 12

if the benedict’s solution remained blue, _______________ reducing sugar

Answer 12

no reducing sguar

Question 13

if the benedict’s solution turned from blue to green, _____________ reducing sugar

Answer 13

traces of

Question 14

if the benedict’s solution turned from blue to yellow/orange, _____________ reducing sugar

Answer 14

moderate amount of

Question 15

if the benedict’s solution turned from blue to red, _____________ reducing sugar

Answer 15

large amount of reducing sugar

Question 16

traces of reducing sugar: benedict’s solution _________

Answer 16

turns from blue to green

Question 17

moderate amount of reducing sugar: benedict’s solution _________

Answer 17

turns from blue to yellow/orange

Question 18

no reducing sugar: benedict’s solution _________

Answer 18

remains blue

Question 19

large amount of reducing sugar: benedict’s solution _________

Answer 19

turns from blue to red

Question 20

what are the three complex carbohydrates / polysaccharides?

Answer 20

1. starch
2. glycogen
3. cellulose

Question 21

what is the main function of carbohydrates?

Answer 21

needed as an immediate source of energy

Question 22

what are the chemical elements that make up carbohydrates?

Answer 22

carbon, hydrogen, oxygen

Question 23

in carbohydrates, the hydrogen and oxygen atoms are present in the ratio __________

Answer 23

2:1

Question 24

starch, glycogen and cellulose are polysaccharides make up of numerous __________ molecules

Answer 24

glucose

Question 25

disaccharides are created when _______________

Answer 25

two monosaccharides are joined together through a condensation reaction

Question 26

what is the role of starch (2 pts) and where does it occur (1 pt)?

Answer 26

1. a storage form of carbohydrates in plants 2. digested to glucose when needed 3. found in storage organs of plants, e.g. potato, tapioca

Question 27

what is the role of glycogen? (2 pts)

Answer 27

1. a storage form of carbohydrates in mammals 2. digested to glucose when needed

Question 28

what is the role of cellulose? (2 pts)

Answer 28

1. cellulose cell wall protects plant cell from bursting/damage 2. serve as a dietary fibre that prevents constipation

Question 29

why are glucose and starch used as storage materials?

Answer 29

1. insoluble in water (they are osmotically inactive so they do not change water potential in cells) 2. large molecules (cannot diffuse across cell membranes, so they will not be lost from cell) 3. easily hydrolysed to glucose when needed for respiration 4. have compact shapes (occupy less space than sum of individual glucose molecules)

Question 30

what is the meaning of hydrolysed

Answer 30

breakdown in the presence of water

Question 31

starch is broken down by ___________ to form maltose

Answer 31

amylase

Question 32

maltose is broken down by _________ to form glucose

Answer 32

maltase

Question 33

what is the test for starch ?

Answer 33

iodine test (using iodine solution)

Question 34

for solid food samples, crush the food using _____________

Answer 34

a mortar and pestle

Question 35

what elements are proteins made up of?

Answer 35

carbon, hydrogen, oxygen and nitrogen

Question 36

each protein molecule is made up of smaller basic units called ___________

Answer 36

amino acids (amino acids are the building blocks of protein)

Question 37

amino acids are made up of _________, __________ & _____________.

Answer 37

amino group, acidic group & a side chain

Question 38

amino acids -------> ____________---------> _____________

Answer 38

polypeptides proteins

Question 39

what happens when proteins are denatured?

Answer 39

they lose their unique 3D shape and lose their ability to function

Question 40

what are the functions of proteins? (5)

Answer 40

1. synthesis of new cytoplasm for growth and repair of worn-out cells 2. synthesis of enzymes and some hormones 3. formation of antibodies to combat diseases 4. source of energy during EXTREME starvation when carbohydrate and fat reserves are depleted. 5. proteins are used for muscle development.

Question 41

what is the test for proteins?

Answer 41

biuret test (using biuret solution)

Question 42

in the absence of protein, the biuret solution will __________________.

Answer 42

remain blue

Question 43

in the presence of protein, the biuret solution will _________________.

Answer 43

turn from blue to violet

Question 44

what elements are fats made up of?

Answer 44

carbon, hydrogen, oxygen

Question 45

unlike carbohydrates, fats contain ________ oxygen compared to hydrogen

Answer 45

MUCH less

Question 46

fats can be broken down into ________ & _________ by _________

Answer 46

fatty acids & glycerol by lipase

Question 47

what are the functions of fats? (5)

Answer 47

1. a long-term storage of energy 2. insulating material that prevents excessive heat loss 3. solvent for fat-soluble vitamins and hormones 4. they form cell membranes 5. oily substance secreted by skin glands reduce rate of evaporation and heat loss from skin surface

Question 48

what is the test for fats?

Answer 48

ethanol emulsion test (using ethanol + water)

Question 49

during an ethanol emulsion test, in the presence of fats, _________________ is formed.

Answer 49

a cloudy white emulsion

Question 50

(ethanol emulsion test) in the absence of fats, ______________

Answer 50

solution will remain clear.