chap3: biological molecules

Question 1

what is carbohydrates and fats made out of

Answer 1

carbon, hydrogen, oxygen

Question 2

purpose of carbohydrates

Answer 2

• carbohydrates are substrates for respiration, provide energy from cell activities (glucose)
  form supporting structures (cell wall in plants) (cellulose)
  converted into other organic compounds like amino acids and fats (glucose)
  for nation of nucleic acids like DNA (glucose)
  synthesis lubricants like mucus (glucose)

Question 3

what is proteins made out of

Answer 3

carbon, hydrogen, oxygen, nitrogen

Question 4

purpose of proteins

Answer 4

synthesis of new cytoplasm for growth and repair of cells
synthesis enzymes and some hormones
formation of antibodies to combat diseases

Question 5

how are proteins formed

Answer 5

when amino acids are joined to form a polypeptide. more polypeptides chains link together and when they are folded together, they form proteins

Question 6

purpose of fats

Answer 6

source and long tern storage of energy
insulating material

Question 7

test for reducing sugar

Answer 7

put food sample in benedict solution and place it in boiling water. if solution remains blue, reducing sugar is absent. if solution turns red, reducing sugar is present

Question 8

test for starch

Answer 8

drop iodine solution on food sample. if it remains brown, starch is absent. if it turns from brown to blue black, starch is present.

Question 9

test for proteins

Answer 9

place food sample in biuret solution. if solution remains blue, proteins is absent. if solution turns from blue to violet, proteins is present.

Question 10

test for fats

Answer 10

place food sample with ethanol solution. if solution remains colourless and no change is observed, fats is absent. if white emulsion is produced, fats is present.