Structure and Functions in Living Organisms - Biological Molecules

Question 1

what chemical elements are present in carbohydrates?

Answer 1

carbon, oxygen and hydrogen

Question 2

what chemical elements are present in proteins?

Answer 2

Carbon, Oxygen, Hydrogen, Sulfur and Nitrogen

Question 3

what chemical elements are present in lipids?

Answer 3

Carbon, Oxygen and Hydrogen

Question 4

what are starch and glycogen made up of?

Answer 4

simple sugars

Question 5

what are proteins made up of?

Answer 5

amino acids

Question 6

what are lipids made up of?

Answer 6

fatty acids and glycerol

Question 7

how do you test for glucose?

Answer 7

• Add a few drops of Benedict’s solution into a test tube of the solution
• Heat test tube placed in a water bath set at 60 - 70 °C for 5 minutes
• if glucose is present, the solution will turn brick-red

Question 8

how do you test for starch?

Answer 8

• Use a pipette to transfer sample solution into wells on a tile
• Add a few drops of Iodine solution
• If Starch is present, the solution will turn blue-black

Question 9

how do you test for protein?

Answer 9

• Add a few drops of Biuret solution into test tube of sample solution
• If Protein is present, solution will turn violet

Question 10

how do you test for lipids?

Answer 10

• Test tube of sample solution is mixed with 2cm^3 of Ethanol and 2cm^3 of distilled water
• If Fat is present, a milky-white emulsion will form

Question 11

what are enzymes?

Answer 11

Protein molecules which act as a biological catalyst by speeding up the rate of specific reactions without being used up or affected

Question 12

what happens to enzymes when temperature increases?

Answer 12

• As the temperature increases towards optimum, the rate of enzyme activity increases
• This is because as temperature increases, enzymes and substrates will gain kinetic energy, vibrating and moving faster. This allows more frequent successful enzyme-substrate collisions to occur.
• However, as temperatures exceed optimum, enzymes will denature

Question 13

how would you investigate how enzyme activity can be affected by temperature?

Answer 13

• a test tube of starch solution is placed in a water bath of set temperature for several minutes
• a solution of amylase enzyme is added
• a pipette is used to add droplets of mixture into wells and a few drops of Iodine solution are added
• the time taken for Starch to be completely broken down is compared

Question 14

what happens to enzymes as pH increases?

Answer 14

• As the pH increases towards optimum, the rate of enzyme activity increases
• However, as pH exceeds optimum, enzymes will denature