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Some students investigated water movement in plant cells - Edexcel - GCSE Biology - Question 5 - 2014 - Paper 1
Question 5
Some students investigated water movement in plant cells. They measured the mass of five pieces of potato. Each piece of potato was put into a different concentratio... show full transcript
Worked Solution & Example Answer:Some students investigated water movement in plant cells - Edexcel - GCSE Biology - Question 5 - 2014 - Paper 1
Step 1
Calculate the percentage change in the mass of the potato in the 20% salt solution.
Answer
To find the percentage change in mass, use the formula:
ext{Percentage Change} = rac{ ext{Final Mass} - ext{Initial Mass}}{ ext{Initial Mass}} imes 100For the 20% salt solution:
- Initial Mass = 10.3 g
- Final Mass = 10.1 g
Substituting these values into the formula gives:
ext{Percentage Change} = rac{10.1 - 10.3}{10.3} imes 100 = rac{-0.2}{10.3} imes 100 \\ ext{Percentage Change} = -1.94 ext{%} \\ ext{(rounded to -1.2%) }Step 2
Suggest why calculating a percentage change is more useful than calculating the change in mass in this investigation.
Answer
Calculating a percentage change provides a better comparison across different sizes or weights of potatoes. It normalizes the results, allowing for a more valid comparison between the pieces with different initial masses. This is particularly important in this investigation, as the pieces of potato varied in size, meaning absolute changes in mass alone could be misleading.