4.1, 5.1 biological molecules, enzymes

Question 1

biological catalyst

Answer 1

substance that increases the rate of a chemical reaction and is not
changed by the reaction

Question 2

enzymes

Answer 2

proteins that are involved in all metabolic reactions, where they function as
biological catalysts

Question 3

importance of enzymes in living organisms in terms of a reaction rate necessary
to sustain life

Answer 3

• Biological reactions are too slow on their own
• Enzymes speed up reactions by lowering the activation energy
  (enzymes lower the amount of energy needed for a reaction)
• does it without the need for high temperatures that would damage cells

Question 4

enzyme - how it breaks down

Answer 4

1) substate will bind to enzyme’s active site
2) forms a substate complex
3) enzyme then catalyzes reaction, breaking down larger molecules to smaller molecules
4) forming a product

Question 5

effect of temperature on enzyme activity

Answer 5

• temp increase = enzyme increase (only up to a point) = increased kinetic energy = enzymes & substrate collide more
• optimum temperature = temperature at which the enzyme works most efficiently (e.g. ~37°C in humans).
• above optimum temp = enzyme becomes denatured (shape changes)
• enzyme stops working.

Question 6

effect of pH on enzyme activity

Answer 6

• each enzyme has an optimum pH at which it works best (e.g. pepsin in the stomach has an optimum pH around 2)
• If the pH is too low or too high, the enzyme’s shape is affected
• causes denaturation
• enzyme activity decreases or completely stops

Question 7

different enzymes

Answer 7

amylase, protease, lipase, catalase

Question 8

amylase

Answer 8

starch catalysed into maltose

Question 9

protease

Answer 9

proteins catalysed into amino acids

Question 10

lipase

Answer 10

lipids catalysed into fatty acids + glycerol

Question 11

catalase

Answer 11

hydrogen peroxide catalysed into water + oxygen

Question 12

chemical elements that make up CARBOHYDRATES

Answer 12

carbon hydrogen oxygen

Question 13

chemical elements that make up fats (lipids)

Answer 13

carbon hydrogen oxygen

Question 14

chemical elements that make up proteins

Answer 14

carbon hydrogen oxygen nitrogen

Question 15

break down of starch, glycogen and cellulose

Answer 15

into glucose

Question 16

break down of proteins

Answer 16

into amino acids

Question 17

break down of fats and oils

Answer 17

into fatty acids and glycerol

Question 18

food test for starch

Answer 18

1- iodine test
if there is starch present = blue black color
no starch = remain yellowish brown color

Question 19

food test for reducing sugars

Answer 19

1- benedicts test
if there is glucose = color changes from blue → green → yellow → orange → brick-red
if no = remains blue color

Question 20

food test for protein

Answer 20

1- biuret’s test
if there is protein = turns purple
if no = remains blue

Question 21

food test for fats and oils

Answer 21

1)- Ethanol Emulsion Test
if there is fats = cloudy layer forms
if no = remains clear

Question 22

food test for vitamin C

Answer 22

1- DCPIP test
if there is = loses colour becomes colourless
if no = remains blue