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Fig. 17.1 shows the mass of urea in the urine plotted against the BMI (Body Mass Index) for nine boys - OCR Gateway - GCSE Biology - Question 17 - 2020 - Paper 1
Question 17
Fig. 17.1 shows the mass of urea in the urine plotted against the BMI (Body Mass Index) for nine boys. BMI is a value often used to see if a person is a healthy mass... show full transcript
Worked Solution & Example Answer:Fig. 17.1 shows the mass of urea in the urine plotted against the BMI (Body Mass Index) for nine boys - OCR Gateway - GCSE Biology - Question 17 - 2020 - Paper 1
Step 1
What does the graph show about the relationship between BMI and the mass of urea in the urine?
Answer
The graph indicates a positive correlation between BMI and the mass of urea in the urine. As the BMI increases, the mass of urea in the urine also tends to increase. This suggests that higher BMIs are associated with higher levels of urea excretion.
Step 2
Calculate the concentration of urea in the boy’s urine.
Answer
To calculate the concentration of urea in the boy's urine, we can use the formula:
Assuming that the mass of urea is derived from the graph for a BMI of 16, let’s assume the mass at this BMI is approximately 1.5 g (as this is a typical value based on the trend). Then,
The volume of urine produced is 1000 cm³.
Thus, the concentration can be calculated as follows:
Therefore, the concentration of urea in the boy's urine is 0.0015 g/cm³.