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Excretion and Homeostasis Introductory — Free MYP3 Sciences Practice Questions
1QuestionConcept of Excretion and Examples in HumansConcept Practice
2 marks~3 minCriterion A
The diagram shows a simplified outline of the human body with three excretory organs labeled A, B, and C.
a
Identify the letter that corresponds to the organ responsible for removing carbon dioxide () from the blood. [1]
b
Explain why removing from the blood is considered excretion rather than simply breathing. [1]
Solutions
2QuestionRole of Kidneys and Urinary SystemAssessment Practice
3 marks~5 minCriterion C
The graph shows kidney filtration rate (mL/min) plotted against blood pressure (mmHg), ranging from 60 mmHg to 180 mmHg.
a
Describe the relationship shown in the graph. [1]
b
Explain why the filtration rate remains constant above 80 mmHg. [1]
c
A patient's blood pressure rises from 80 mmHg to 160 mmHg during exercise. Using the graph and your knowledge of kidney autoregulation, explain whether this change is likely to damage the glomeruli. [1]
Solutions
3QuestionConcept of Excretion and Examples in HumansAssessment Practice
6 marks~9 minCriterion D
A patient with kidney failure undergoes dialysis. Blood passes through a machine containing a specialised filter that removes waste products such as urea, and the cleaned blood is returned to the body.
a
Describe the role of healthy kidneys in removing waste products from the blood. [1]
b
Explain how a dialysis machine performs the same function as healthy kidneys. [2]
c
A doctor tells the patient: "Dialysis keeps you alive, but it cannot fully replace what your kidneys do." Using your knowledge of kidney function, analyse this statement and decide whether you agree or disagree. Support your answer with one advantage and one disadvantage of dialysis compared to healthy kidneys. [3]
Solutions
4QuestionRole of Kidneys and Urinary SystemAssessment Practice
4 marks~6 minCriterion B
A student investigates how fluid intake affects urine output. They drink different volumes of water and measure total urine produced over two hours.
| Water intake (mL) | 0 | 200 | 400 | 600 |
|---|---|---|---|---|
| Urine volume (mL) | 50 | 180 | 350 | 530 |
a
Describe the relationship between water intake and urine volume shown in the data. [1]
b
Explain why the body produces different volumes of urine at different levels of water intake. [1]
c
A second student drinks 800 mL of water. Use the data to predict their urine volume and justify your prediction. [2]
Solutions
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