BIOLOGY 5090 · STRUCTURED PRACTICE
An investigation was conducted into the rate of photosynthesis in an aquatic plant (Elodea canadensis) submerged in water at 20 °C. The volume of oxygen gas collected per minute was measured across a range of light intensities under two dissolved carbon dioxide concentrations: Curve 1 (0.03% ) and Curve 2 (0.12% ).
State the balanced chemical equation for photosynthesis.
Using Curve 1, state the rate of oxygen production at a light intensity of 40 arbitrary units.
Describe the effect of increasing light intensity from 0 to 80 arbitrary units on the rate of oxygen production in Curve 1.
Identify the limiting factor along Curve 1 between 0 and 20 arbitrary units, and justify your answer using evidence from the graph.
Explain why Curve 1 levels off at 40 arbitrary units while Curve 2 continues to rise.
Calculate the percentage increase in the maximum photosynthetic rate when the carbon dioxide concentration is increased from 0.03% (Curve 1 plateau = 4.0 cm³ min⁻¹) to 0.12% (Curve 2 plateau = 9.0 cm³ min⁻¹).
Total: 11 marks