Biological Molecules

Which is an enzyme involved in the digestion of proteins in the stomach?

• amylase

• bile

• lipase

• protease

Which chemical element is found in proteins, but not in carbohydrates or fats?

• carbon

• hydrogen

• oxygen

• nitrogen

One method of preventing food spoilage is to store it at

4 °C in a refrigerator. Why does storing food at low temperatures help to prevent food spoilage?

• It decreases enzyme activity.

• It denatures enzymes.

• It increases enzyme production.

• It kills cells.

What is needed in a cell to make a protein molecule?

• amino acids and energy

• amino acids and glycerol

• energy and glycerol

• glycerol

Which statement about all enzymes is correct?

• They are used up in the reaction they catalyse.

• They speed up reactions.

• C They work best above 40 °C.

• They work best at a pH of 7.0.

The graph shows the rate at which 10g of starch is broken down by amylase at four temperatures.

Which is the optimum temperature?

• 10°C

• 25°C

• 40°C

• 70°C

An investigation was carried out to see the effect of temperature on how quickly the enzyme

amylase breaks down starch to sugar.

Which labels should be used for the axes and what has happened at point Z?

• x-axis - rate of breakdown of starch

  y-axis - temperature

  what has happened at Z - enzyme is denatured

• x-axis - temperature

  y-axis - time taken to breakdown starch

  what has happened at Z - enzyme is denatured

• x-axis - temperature

  y-axis - rate of break down of starch

  what has happened at Z - enzyme is denatured

• x-axis - time taken to break down starch

  y-axis - temperature

  what has happened at Z - enzyme is used up

Which statement about enzyme action is correct?

• The active site of the enzyme is complementary to the product and a substrate is formed.

• The active site of the substrate is complementary to the enzyme and a product is formed.

• The active site of the product is complementary to the enzyme and a substrate is formed.

• The active site of the enzyme is complementary to the substrate and a product is formed.

Four foods were tested for

fat (using ethanol)

protein (using the biuret test)

reducing sugar (using Benedict's solution)

starch (using iodine solution)

Which food contains protein and starch?

• A

• B

• C

• D

The diagram shows the action of amylase. What is the function of the enzyme amylase?

• breaks down the substrate into amino acids

• changes the product into the substrate

• increases the rate of starch breaking down into glucose

• increases the rate of starch breaking down into maltose