Biological Molecules

Question 1

elements in carbohydrates

Answer 1

Carbon, Hydrogen, Oxygen

Question 2

elements in proteins

Answer 2

Carbon, Hydrogen, Oxygen, Nitrogen, Sulfur

Question 3

elements in lipids (fats and oils)

Answer 3

Carbon, Hydrogen, Oxygen

Question 4

Monomer

Answer 4

Simple single units

Question 5

Polymer

Answer 5

Chain of monomers bonded together

Question 6

carbohydrates structure

Answer 6

• Carbohydrates (starch+glycogen) = polysaccharide
• Simple sugar (glucose) = monosaccharide

Question 7

protein structure

Answer 7

• Made up of amino acids (monomers)
• Used for growth and repair

Question 8

lipids structure

Answer 8

• Made up of glycerol and 3 fatty acid tails
• Used for insulation
• Protect organs from mechanical damage

Question 9

protein test

Answer 9

BIURET’S TEST
1. prepare 5ml sample food
2. add 5ml biuret’s solution
3. mix
4. observe colour change
negative = blue
positive = purple

Question 10

glucose test

Answer 10

BENEDICT’S TEST
1. prepare food sample
2. put 5ml food sample into test tube
3. add 5ml Benedict’s solution
4. place tube in water bath at 80°C for 10 mins
5. record colour after 10 mins
negative result = blue
positive result:
low = green/yellow
medium = orange
high = brick red

Question 11

starch test

Answer 11

IODINE SOLUTION TEST
1. prepare food sample
2. place small sample of food on spotting tile
3. add 2-3 drops of iodine solution to food sample
4. observe colour change
negative result = orange/brown
positive result = blue/black

Question 12

lipids test

Answer 12

EMULSION TEST
1. place small spatula of food sample in test tube
2. add 5ml ethanol and shake
3. add 5ml water and mix
4. observe result
negative result = solution will remain clear
positive result = solution will turn cloudy white