1. lipids and carbs fact test

Question 1

what is a monomer

Answer 1

the smaller units from which larger molecules are made

Question 2

what is a polymer

Answer 2

molecules made from a large number of monomers joined together

Question 3

what are some examples of monomers

Answer 3

monosaccharides, amino acids and nuceotides

Question 4

what are some examples of polymers

Answer 4

polysaccharides, proteins, polypeptides and DNA

Question 5

what is a condensation reaction

Answer 5

joins 2 molecules together with the formation of a chemical bond and involves the elimination of a water molecule

Question 6

what is a hydrolysis reaction

Answer 6

breaks a chemical bond between 2 molecules and involves the use of a water molecule

Question 7

what are monosaccharides

Answer 7

monomers from which larger carbohydrates are made

Question 8

what are some common monosaccharides

Answer 8

glucose, fructose and galactose

Question 9

what does a condensation reaction between 2 monosaccharides form

Answer 9

a glycosidic bond

Question 10

what are disaccharides

Answer 10

formed by the condensation between 2 monosaccharides

Question 11

what monosaccharides make the disaccharide maltose

Answer 11

2 glucose molecules

Question 12

what monosaccharides make the disaccharide sucrose

Answer 12

glucose and fructose

Question 13

what monosaccharides make the disaccharide lactose

Answer 13

glucose and galactose

Question 14

what are the 2 isomers of glucose called

Answer 14

alpha glucose
beta glucose

Question 15

what are polysaccharides

Answer 15

formed by the condensation of many glucose units

Question 16

what are the 4 polysaccharides

Answer 16

cellulose
starch - amylose
starch - amylopectin
glycogen

Question 17

what is cellulose like

Answer 17

• found in plants
• unbranched
• made of beta glucose
• bond between monomers is 1-4
• provides strength
• long, straight unbranched chains of beta glucose
  joined by hydrogen bonding to form microfibrils which provides strength

Question 18

what is starch (amylose) like

Answer 18

• found in plants
• unbranched
• made of alpha glucose
• bond between monomers is 1-4
• stores energy

Question 19

what is starch (amylopectin) like

Answer 19

• found in plants
• branched
• made of alpha glucose
• bonds between monomers are -4 and 1-6
  stores energy
• branched therefore more ends for faster hydrolysis

Question 20

what is glycogen like

Answer 20

• found in animals
• branched
• made of alpha glucose
• bonds between monomers is 1-4 and 1-6
• stores energy
• branched therefore more ends for faster hydrolysis

Question 21

what do amylose, amylopectin and glycogen have in common

Answer 21

• polymer of alpha glucose so easily hydrolysed to provide glucose for respiration
• has coils therefore compact
• made of glucose so provides respiratory substrate for energy release
• insoluble so doesn’t affect water potential/osmosis
• large molecule so can’t cross the cell membrane

Question 22

what is the test for starch

Answer 22

• grind/crush food sample
• add iodine in potassium iodide solution
• positive result is colour change from orange/brown to blue/black

Question 23

what are reducing sugars

Answer 23

a reducing sugar is a sugar that can donate electrons (i.e. reduce) another chemical e.g benedict’s reagent

Question 24

what are some examples of reducing sugars

Answer 24

all monosaccharides and some disaccharides e.g maltose

Question 25

how do you test for reducing sugars

Answer 25

• add benedict’s solution and heat in a hot water bath
• positive result is colour change from blue to brick red

Question 26

what are non-reducing sugars

Answer 26

don’t change colour when heated with benedict’s solution

Question 27

how do you detect non-reducing sugars

Answer 27

sample must first be hydrolysed into it’s constituent monosaccharides

Question 28

what are some examples of non-reducing sugars

Answer 28

some disaccharides e.g sucrose

Question 29

what is the test for non-reducing sugars

Answer 29

• first confirm no reducing sugars are present
• get a fresh sample
  boil in acid (e.g hydrochloric) which will hydrolyse any dissacharide present into its constituent monosaccharides
• neutralise (e.g sodium hydrogen carbonate) as benedict’s reagent will not work in acidic conditions
• add benedict’s reagent and heat in a hot water bath
• observe colour change

Question 30

what are lipids

Answer 30

• not polymers as they aren’t made up of repeating units
• made up of carbon, hydrogen and oxygen
• insoluble in water, soluble in alcohols

Question 31

what are the roles of lipids

Answer 31

• cell membranes
• energy source
• water proofing
• insulation
• protection

Question 32

how do you carry out the emulsion test (test for lipids)

Answer 32

• add ethanol to substance
• add water
• positive result is milky white emulsion
• negative result is colourless

Question 33

what are triglycerides

Answer 33

1 glycerol molecule bonded to 3 fatty acid chains
3 water molecules are eliminated to make a triglyceride

Question 34

what is an ester bond

Answer 34

covalent bond between glycerol and fatty acid formed by condensation reaction and broken by hydrolysis reaction

Question 35

where is the ester bond always formed

Answer 35

the side with the COOH group

Question 36

what are saturated fatty acids

Answer 36

all C-C single bonds
carbons are fully saturated with hydrogen atoms
tend to form fats
solid at room temperature

Question 37

what are unsaturated fatty acids

Answer 37

can be monounsaturated - only one C=C double bond
can be polyunsaturated - many C=C double bonds
tend to form oils and are liquid at room temperature

Question 38

what are phospholipids

Answer 38

1 glycerol bonded to 2 fatty acids and one phosphate group

Question 39

what does amphiphilic mean

Answer 39

a molecule having both hydrophobic (non-polar) and hydrophilic (polar) regions

e.g. phospholipids