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A scientist investigated the effects of different fertilisers on the growth of spinach plants - AQA - A-Level Biology - Question 7 - 2020 - Paper 1
Question 7
A scientist investigated the effects of different fertilisers on the growth of spinach plants. The scientist: - set up a large sample of identical pots of soil - ad... show full transcript
Worked Solution & Example Answer:A scientist investigated the effects of different fertilisers on the growth of spinach plants - AQA - A-Level Biology - Question 7 - 2020 - Paper 1
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 determine how many times greater the mean growth rate per day is using the two types of fertilisers, we need the average final biomass for each fertiliser group. Assuming that potassium nitrate resulted in a biomass of 1.375 g and ammonium sulfate resulted in a biomass of 1 g, we can use the formula:
ext{Times greater} = rac{ ext{Mean biomass with potassium nitrate}}{ ext{Mean biomass with ammonium sulfate}} = rac{1.375}{1.0} = 1.375Thus, the mean growth rate per day using potassium nitrate is 1.375 times greater than using ammonium sulfate.
Step 2
Using all the information, evaluate the effect on plant growth of adding the different fertilisers to the soil.
Answer
The evaluation of the effect of various fertilisers can be understood through several considerations:
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Fertility Contribution: Different types of fertilisers contain varying nutrient compositions that contribute to plant growth. For example, nitrogen, which is abundant in chicken manure and other fertilisers, plays a crucial role in protein synthesis and overall growth.
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Nutrient Effectiveness: Results indicate that the effectiveness of chicken manure decreases after about 60 grams added per pot. Exceeding this amount may lead to nutrient saturation and hinder plant growth.
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Statistical Analysis: It is important to mention that there was no statistical test conducted, which means we cannot conclusively determine if the observed differences in biomass are significant or merely due to random variation.
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Contextual Factors: Variables such as soil type, watering, and environmental conditions can also affect the plant growth results, highlighting the need for controlled experiments.
In conclusion, the usage of specific fertilisers did seem to improve the biomass of spinach plants compared to a control, particularly with potassium nitrate at effective doses.
Step 3
Suggest what the scientist should do to ensure that he has removed all the water from the sample.
Answer
The scientist should continue to heat the sample until it reaches a constant mass. This method ensures that all the water has evaporated, as the mass would remain unchanged when all moisture has been eliminated. It's important to monitor the sample closely and weigh it periodically during drying to confirm that the mass stabilizes.