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Populations in ecosystems (A-level only)

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Question 5

Glyphosate is a widely used herbicide. Scientists investigated the rate of glyphosate breakdown by soil microorganisms at two different temperature treatments: 15∘C15^\circ\text{C}15∘C and 25∘C25^\circ\text{C}25∘C.

They measured the concentration of glyphosate in soil samples over 10 days. Each sample started with the same concentration of glyphosate and had the exact same soil mass. Their results are shown in the graph below:

Graph showing glyphosate concentration in soil over 10 days at two temperatures. The x-axis is 'Time / days' ranging from 0 to 10 with grid lines every 1 day. The y-axis is 'Concentration of glyphosate / \mu g g^{-1}' ranging from 0 to 40 with grid lines every 2 units. Both curves start at 40 \mu g g^{-1} at Day 0. The 25 ^\circ C curve (solid line) drops rapidly, passing exactly through (3, 10) and reaching 2 units at Day 6. The 15 ^ imes C curve (dashed line) drops more slowly, passing exactly through (3, 25) and reaching 10 units at Day 6.

1.

Suggest why, in this investigation, the scientists expressed the concentration of glyphosate in units of μg g−1\mu\text{g }\text{g}^{-1}μg g−1.

[2]
2.

Calculate the difference in the rate of breakdown of glyphosate per day between day 0 and day 3 at 15∘C15^\circ\text{C}15∘C and 25∘C25^\circ\text{C}25∘C. Show your working and state the units for your answer.

[3]

Populations in ecosystems (A-level only) Questions

  1. A Level
  2. /Biology
  3. /Populations in ecosystems (A-level only)