nutrition

Question 1

functions of water

Answer 1

1. a solvent for many chemical reactions
2. medium for chemical reactions
3. needed for hydrolysis
4. plays a role in regulation of body temperature in warm blooded animals
5. trasnport dissolved substances around the body
6. key component of various fluids in body

Question 2

carbohydrates made of?

Answer 2

1. carbon, hydrogen, oxygen
2. presence of oxygen and hydrogen 1:2

Question 3

simple suagrs

Answer 3

1. monosaccharides
   - glucose
   - fructose
   - galactose
2. disaccharide
   - maltose
   - sucrose
   - lactose

Question 4

complex carbohydrates

Answer 4

3. polysaccharides
   - starch
   - glycogen
   - cellulose

Question 5

monosaccharide characteristics

Answer 5

1. C6H12O6
2. can pass throguh cell membrane
3. further broken down to release energy
   - glucose: in animals and plants
   - fructose: in animals
   - galactose: present in milk sugars in mammals
4. diff arrangement of atoms

Question 6

disaccharide charateristics

Answer 6

1. formed by condensation of two monosaccharide moleculs
2. same chemical formula of C12H22O11
3. diff arrangement of atoms

glucose + glucose -> maltose + water

Question 7

hydrolysis meaning and example

Answer 7

cemical reaction to chemically break down a complex substance to form a simple substace, it requires one molecule of water

maltose + water -> glucose + glucose

Question 8

reducing suagrs

Answer 8

all carbohydrates are reducing sugars EXCEPT SUCROSE

Question 9

polysaccharides characteristics

Answer 9

many condensed monosaccharides cehmically combined together

starch: plant storage organs
cellulose: plants
glycogen: liver and musles of mammals
they are all made of glucose molecules w diff arrangements

Question 10

fats made up of?

Answer 10

carbon hydrogen oxygen
less oxygen than hydrogen
proporation of elements are not fixed

Question 11

fats charateristics

Answer 11

one glycerol molecule and 3 fatty acids chains
insoluble in water
soluble in organic solvents

Question 12

hydrolysis of fats

Answer 12

fats + 3H20 -> one glycerol + three fatty acids molecules

Question 13

proteins made up of ?

Answer 13

carbon hydrogen nitrogen oxygen
may contain sulfur and phosphorus

Question 14

formation of proteins

Answer 14

amino acids are linked up by peptide bonds to form a polypeptide
2 or more polypeptide chains fold to form a protein

Question 15

uses of proteins

Answer 15

• synthesis of new protoplasm
• make antibodies
• make enzymes
• make hormones
• last source of energy in body

Question 16

Benedict’s test

Answer 16

for reducing sugar

1. add 2cm3 of Benedict’s solution into 2cm3 of sample and shake
2. place into boiling water bath

brick-red precipitate forms -> high conc of RS present
mixture remains blue -> no reducing suagr present

Question 17

Biuret’s test

Answer 17

test for proteins

1. add 2cm3 of sample into 2cm3 of aqueous sodium hydroxide
2. shake
3. add 1% of copper (II) sulfate solution drop by drop, shaking ater each drop

violet colouration seen -> prteins present
no violet colouration seen -> no proteins

Question 18

iodinetest

Answer 18

test for starch

place sample onto a white tile
add a few drops of iodine

turns blue black if got starch
remians yellowish brown if there is no starch

Question 19

ethanol emulsion test

Answer 19

test for fats

to 2cm3 of sample, add2cm3 of ethanol
shake
add water to mixture

white emulcion->fat present
no white emulsion -> no fats present

Question 20

how tondo food tests for SOLID subs

Answer 20

cut into smaller pieces
place into test tube and add xxcm3 of water
shake
decant mixture into new test tube
-> pouring liquid portion of oxyture and leaving behind solid sample