Biological Molecules Level 2

Which chemical test can be used to test for reducing sugars?

• Benedict's solution

• Biuret solution

• Iodine test

• Ethanol Emulsion test

Which chemical test can be used to test for the presence of an enzyme in a washing powder?

• Ethanol emulsion test

• Benedict's test

• Iodine test

• Biuret test

4 different foods were tested as shown and the results recorded as positive (+) or negative (-). Which food contains both glucose and fats?

• A

• B

• C

• D

Which food test shows a violet colour if the molecule is present?

• Reducing sugars

• Proteins

• Starch

• Fats

An enzyme loses its ability to catalyse a reaction when it is heated above its optimum temperature. What is the reason for this?

• Its activation energy is lowered.

• Its active site is denatured.

• The frequency of molecular collisions is increased.

• The substrate is denatured.

The diagram represents enzyme action. Which of the following are the correct labels?

• W- enzyme
  X- products
  Y- substrate

• W- enzyme
  X- substrate
  Y- products

• W- substrate

  X- products
  Y- enzyme

• W- substrate
  X- enzyme
  Y- products

What effect does increasing the temperature from 10c to 80c have on the activity of an enzyme present in the digestive system?

• Speeds it up then slows to zero

• Speeds it up and remains constant

• Slows it down to zero

• Slows it down then speeds up

Which two factors, when changed, can cause enzymes to denature?

• pH and water potential

• temperature and concentration

• pH and temperature

• temperature and time

The graph shows the effect of pH on a particular enzyme controlled reaction. When is the enzyme NOT active?

• at pH 1 and pH 13

• at pH 3 and pH 11

• at pH 5 and pH 9

• at pH 7

What is a characteristic of all catalysts?

• They are broken down in the reaction.

• They are made of protein.

• They are not changed by the reaction.

• They decrease the rate of reaction.