Photo AI
All the volunteers were given the same food for 3 days - AQA - A-Level Biology - Question 5 - 2018 - Paper 2
Question 5
All the volunteers were given the same food for 3 days. Suggest and explain one reason why they were given the same food. Using Table 1, what can you conclude abou... show full transcript
Worked Solution & Example Answer:All the volunteers were given the same food for 3 days - AQA - A-Level Biology - Question 5 - 2018 - Paper 2
Step 1
Suggest and explain one reason why they were given the same food.
Answer
The volunteers were given the same food to control for dietary variables that could affect urine production. By standardizing their diet, the researchers ensured that any differences in urine output were due to the treatments administered and not variations in food intake, which could influence fluid balance and kidney function.
Step 2
Using Table 1, what can you conclude about the effectiveness of furosemide and CVT in the removal of excess fluid from the body?
Answer
Furosemide and CVT are both more effective than the placebo (Group C) in promoting urine production. The data shows that both treatments led to a significantly higher mean volume of urine produced in 4 hours, indicating their effectiveness in removing excess fluid from the body.
Step 3
Step 4
Explain how furosemide causes an increase in the volume of urine produced.
Answer
Furosemide inhibits the reabsorption of sodium and chloride ions in the renal tubules. This inhibition leads to a decrease in the osmotic gradient in the filtrate, resulting in less water being reabsorbed back into the blood. Consequently, more water remains in the filtrate, increasing urine volume. Specifically, this occurs at the loop of Henle, where water is not reabsorbed due to the changes in osmotic pressure.
Step 5
How much greater is the flow of blood into the kidneys with furosemide than with group C (placebo) over the 4 hours of the investigation?
Answer
The mean rate of flow of blood plasma into the kidneys with furosemide is 380 cm³/min. For the placebo group, the flow is 295 cm³/min. The difference over 4 hours can be calculated as follows:
- 4 hours = 240 minutes
- Flow with furosemide: 380 cm³/min × 240 min = 91200 cm³
- Flow with placebo: 295 cm³/min × 240 min = 70800 cm³
The difference is 91200 cm³ - 70800 cm³ = 20400 cm³. Thus, the flow of blood into the kidneys with furosemide is 20400 cm³ greater than with the placebo.