1. Describe the function of the digestive system.
Answer
To digest and absorb food.
2. How can a problem with a person's pacemaker be treated ?
Answer
People with problems with their pacemaker can have an artificial pacemaker fitted (an electrical device used to correct irregularities in the heart rate).
3. Define the term "carcinogen" and give two examples.
Answer
A carcinogen is a chemical or agent that causes cancer by damaging DNA and causing mutations, for example, tar in cigarettes, asbestos, UV, X-rays.
4. Amylase (carbohydrase), lipase and protease are digestive enzymes. Show where each of them is produced.
Answer
Amylase is produced in the salivary glands and the pancreas. Lipase is produced in the pancreas. Protease is produced in the stomach and the pancreas.
5. A student investigates the effect of pH on the rate of reaction of the enzyme amylase. Buffer solution, starch solution, and amylase solution are mixed together and kept at 35°C in a water bath. At 30 second intervals, samples of the reaction mixture are added to iodine solution. The time taken until the iodine no longer turns blue–black is recorded. The investigation is repeated using buffer solutions of different pH values.
a) Suggest why measuring the concentration of starch every 30 seconds would be better than recording a colour change.
b) Suggest one way the student could more accurately measure the time taken for all of the starch to break down.
c) The student repeats the investigation using a pH 2 buffer solution, starch solution and amylase solution. After 15 minutes, the iodine solution still turns blue–black. Explain why.
Answer
a) Gives a more accurate measurement of the amount of starch. It is a quantitative measure whereas colour change is subjective.
b) Remove drops of the mixture more frequently (for example, every 10 or 20 seconds).
c) The enzyme denatures at the low (or acidic) pH. The active site changes shape so the substrate will not fit.
6. State the location and the function of the "pacemaker" of the heart.
Answer
The "pacemaker" is a group of cells located in the right atrium that controls the natural resting heart rate.
7. Give some situations when an artificial heart might be used.
Answer
Artificial hearts are used to keep patients alive while they are waiting for a heart transplant, or to let the heart rest to help it recover.
8. Explain shortly the function of red blood cells, white blood cells, platelets and plasma.
Answer
Red blood cells transport oxygen around the body.
White blood cells destroy pathogens.
Platelets help blood to clot.
Plasma transports substances around the body in solution.
9. Risk factors are linked to an increased rate of a disease. Explain the difference between causation and correlation with risk factors.
Answer
Causation - There is a causal mechanism that has been proven for some risk factors, for example, chemicals in cigarette smoke have been shown to cause cancer in laboratory animals.
Correlation - There is a relationship between two variables, but this does not mean that one causes the other.
10. Describe the human and financial costs of excess alcohol consumption.
Answer
Human costs include increased crime, violence, antisocial behaviour, death or injury from drink driving. Financial costs include expense to NHS of treatment for injuries or alcoholism, loss of earnings due to absence from work or inability to work.