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The effect of temperature on decomposition was investigated - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1
Question 3
The effect of temperature on decomposition was investigated. 30 leaves were collected. This mass of five leaves was recorded and the leaves were placed into a net b... show full transcript
Worked Solution & Example Answer:The effect of temperature on decomposition was investigated - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1
Step 1
Calculate the percentage decrease in mass for the leaves at 85°C.
Answer
To calculate the percentage decrease in mass, use the formula:
ext{Percentage Decrease} = rac{ ext{Mass at start} - ext{Mass after 25 days}}{ ext{Mass at start}} imes 100For the leaves at 85°C:
- Mass at start = 5.4 g
- Mass after 25 days = 5.2 g
Substituting the values:
ext{Percentage Decrease} = rac{5.4 - 5.2}{5.4} imes 100 = rac{0.2}{5.4} imes 100 \\ ext{Percentage Decrease} \\ ightarrow 3.70\% \\ ext{(to two significant figures: 3.7\%)}Step 2
Explain which temperature was the best for the decomposition of the leaves.
Answer
The best temperature for decomposition of the leaves can be determined by analyzing the percentage decrease in mass over the 25-day period. From the provided data:
- The temperature of 70°C resulted in a 26% decrease in mass, which is the highest percentage among all temperatures recorded.
Therefore, 70°C is the best temperature for decomposition, as it facilitated the most significant breakdown of the leaf mass, indicating optimal conditions for microbial activity and decomposition processes.
Step 3
State two improvements to the method for this investigation.
Answer
- Use more leaves or more bags of leaves to ensure a larger sample size, which could provide more reliable data on decomposition rates.
- Check the mass at regular time intervals to gather more frequent data on the decomposition process and observe trends over time.