Urine tests may be used to diagnose diseases.
Indicator paper strips are placed into a urine sample. They detect substances in the sample that are excreted in urine but are not usually found in the urine of a healthy person.
Three examples of indicator paper strips are:
• Diastix® to detect glucose
• Albustix® to detect protein
• Ketostix® to detect ketones.
People with diabetes excrete glucose and ketones.
People with nephritis excrete protein.
People with malnutrition excrete ketones.
Table 3.1 gives the results of tests on the urine samples of four individuals (D, E, F and G). A tick (✓) shows a positive result and a cross (✗) shows a negative result.
(a(i))[1]
State which individual is healthy, and explain your choice.
(a(ii))[2]
State which individual has diabetes, and explain your decision.
(b)[6]
Healthy human urine normally has a pH of 6.5. Universal indicator paper strips can be used to measure urine pH.
A scientist wants to find out whether the pH of human urine changes with the volume of water drunk. For her investigation, she chooses 20 healthy female volunteers who are similar in age and weight.
Plan a method the scientist could use for her investigation.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “F, because all tests are negative (AW)” …