MCQ-2: Biological Molecules

The diagram shows two food molecules before and after they have been digested by enzymes.

What identifies the products of fat digestion?

Four foods were tested for each of the following nutrients:

• fat (using ethanol);
• protein (using the biuret test);
• reducing sugar (using Benedict’s solution),

Which food contains protein and fat?

key
✓= nutrient present
x = nutrient absent

Which simple molecules are the basic units of protein?

Which substance catalyses the breakdown of fats to fatty acids and glycerol?

Commercial fishermen use ice to store the fish that they catch.
How does the ice keep the fish fresh?

The roots of plants take up nitrates from the soil.
What are the nitrates used to make?

An experiment is set up to investigate gas exchange in aquatic plants.

The hydrogencarbonate indicator solution is orange at the start.
Which colour is it after three hours?

The diagram shows the structure of part of a DNA molecule.

What does X represent?

What is the colour change shown by Benedict’s solution when heated with a reducing sugar?

Two pieces of an aquatic plant were placed into two different test-tubes, P and Q.
Each test-tube contained hydrogencarbonate indicator and was sealed and kept at 20 °C.
Test-tube P was kept in the light and test-tube Q was kept in the dark.
The table shows the effect of carbon dioxide on the colour of the hydrogencarbonate indicator.

What would the colour of the indicator be after 12 hours?

The data show the concentrations of sugar and starch in an onion.

The onion is tested with Benedict’s solution and iodine solution.
Which set of results is correct?

Which statement about the structure of DNA is correct?

The base sequence of part of one strand of a DNA molecule is shown.
ATAGCC
What is the base sequence of the other strand?

Which processes depend on the fact that water is a solvent?

Which identifies the chemical elements found in proteins?

key
✓ = present
x = absent

A student carries out a test to see whether the solution in a test-tube contains protein.
Which row shows the correct food test and a positive result?