Question 1
FFertiliser from a farm washed into a lake.
Scientists measured the number of algal cells and the concentration of dissolved oxygen in the lake water every week.
The Figure shows the results.
Figure
a.[1]
Give the week in which the number of algal cells was highest.
b.[2]
Calculate the percentage decrease in the concentration of dissolved oxygen between week 0 and week 7.
Give your answer to one decimal place.
c.[2]
Explain why the number of algal cells increased between week 1 and week 4.
d.[3]
Explain why the concentration of dissolved oxygen decreased after week 4.
e.[1]
Suggest why the concentration of dissolved oxygen increased after week 8.
9.2 Energy transfer and biodiversity Questions
38 exam-style questions on Edexcel GCSE Biology 9.2 Energy transfer and biodiversity, covering 9.2.1 Energy transfer between trophic levels, 9.2.2 Efficiency of energy transfers, 9.2.3 Human interactions and biodiversity, 9.2.4 Benefits of maintaining biodiversity, and 9.2.5 Biological factors affecting food security. Each one has a worked solution and a mark scheme showing where the marks go.