Sucrase is an enzyme found in the small intestine. It breaks down sucrose into glucose and fructose.
Which term describes sucrose in this reaction?
Put a cross ( ☒ ) in the box next to your answer.
☐ A active site
☐ B enzyme
☐ C product
☐ D substrate
Name the part of the sucrase molecule that sucrose binds to.
Sucrase cannot break down lactose.
Explain why.
Enzymes in the digestive system break down large food molecules into small soluble molecules.
Trypsin is a protease.
Which substances are produced when trypsin digests its substrate?
Put a cross ( ☒ ) in the box next to your answer.
☐ A sugars
☐ B amino acids
☐ C fatty acids
☐ D starches
Lipase digests the lipid in food.
Name the two products of this reaction.
Celery contains the enzyme catalase, which breaks down hydrogen peroxide into oxygen and water.
A student added the same mass of celery to hydrogen peroxide solution at different temperatures and measured the volume of oxygen produced in 60 seconds.
| Temperature (°C) | Volume of oxygen produced in 60 s (cm³) |
|---|---|
| 10 | 4 |
| 20 | 9 |
| 30 | 17 |
| 40 | 24 |
| 50 | 11 |
| 60 | 0 |
State the optimum temperature for catalase shown by these results.
Explain why no oxygen was produced at 60 °C.
Milk is cloudy because it contains protein. When a protease digests this protein the milk becomes clear.
A student added protease solutions of different concentrations to milk and measured the time taken for the milk to become clear. The student calculated the rate of reaction using .
| Protease concentration (%) | Time for milk to become clear (s) | Rate () |
|---|---|---|
| 0.5 | 400 | 0.003 |
| 1.0 | 250 | 0.004 |
| 1.5 | 140 | |
| 2.0 | 80 | 0.013 |
Calculate the rate of reaction for the 1.5% protease solution. Give your answer to three decimal places.
..............................................................
Name the dependent variable in this investigation.
