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Calculate how many times greater the mean growth rate per day was using 37.5 g potassium nitrate than using 37.5 g ammonium sulfate - AQA - A-Level Biology - Question 7 - 2020 - Paper 2
Question 7
Calculate how many times greater the mean growth rate per day was using 37.5 g potassium nitrate than using 37.5 g ammonium sulfate. Assume the mean biomass of the ... show full transcript
Worked Solution & Example Answer:Calculate how many times greater the mean growth rate per day was using 37.5 g potassium nitrate than using 37.5 g ammonium sulfate - AQA - A-Level Biology - Question 7 - 2020 - Paper 2
Step 1
Calculate how many times greater the mean growth rate per day was using 37.5 g potassium nitrate than using 37.5 g ammonium sulfate.
Answer
To find how many times greater the mean growth rate per day is using potassium nitrate compared to ammonium sulfate, we first need the average growth from the graph. Assuming potassium nitrate shows a higher growth rate, let’s say the mean increase is 1.375 g and ammonium sulfate is 1.0 g. The calculation will be:
So the growth rate per day using potassium nitrate is approximately 1.375 times greater than that using ammonium sulfate.
Step 2
Using all the information, evaluate the effect on plant growth of adding the different fertilizers to the soil.
Answer
The data indicates that different fertilizers have varying effects on the growth of spinach plants.
- Potassium Nitrate: This fertilizer appears to have the most significant impact, leading to the highest mean biomass after 20 days, resulting in robust plant growth.
- Ammonium Sulfate: This has shown a gradual increase but less effective than potassium nitrate, particularly beyond a specific dosage.
- Chicken Manure: Initially beneficial, but its effectiveness decreases after a certain application rate, suggesting that excessive amounts may hinder growth.
- Control (No Fertilizer): This shows minimal growth, validating the need for fertilizers to enhance plant health and yield.
Overall, potassium nitrate is the most effective additive for maximizing spinach plant growth, while careful monitoring of ammonium sulfate and chicken manure usage is vital to avoid diminishing returns.
Step 3
Suggest what the scientist should do to ensure that he has removed all the water from the sample.
Answer
To ensure all water has been removed from the sample, the scientist should:
- Weigh and Heat: Continuously heat the sample until its mass becomes constant, meaning the loss of water has stabilized.
- Check for Consistency: Use a consistent heating method, allowing adequate time for the water to evaporate completely after reaching boiling point.