Does more light always mean more photosynthesis? Investigate how two inputs can limit oxygen production in a model aquatic plant.
Illustrative simulation imagery
Learning target
I can design a controlled test to explain how light and carbon dioxide availability affect a photosynthesis model.
I know I am successful when…
I change one input at a time, compare at least three trials, and use the data to identify a limiting input.
Your investigation
Keep carbon dioxide at 80%. Test light at 0%, 25%, 50%, 75%, and 100%.
Set carbon dioxide to 20% and repeat those light settings.
Compare the two patterns. Then hold light at 75% and change only carbon dioxide.
Vocabulary: photosynthesis uses light energy to help build sugars from carbon dioxide and water; oxygen is released. A limiting input restricts the model’s output.
Run a photosynthesis trial
Keep water available, plant size, and temperature constant. These are relative input settings and simulated oxygen units—not measured light intensity, real carbon dioxide percentages, or real plant rates.
Relative light: 50%
Recorded trials 0Latest oxygen output — model units
Choose settings, then run a trial. Changing a control does not record data until you select Run.
Green line: recorded oxygen output, in the order you ran the trials. Compare the light and carbon dioxide settings in the data table.
Your recorded data
Trial
Relative light (%)
Relative CO₂ availability (%)
Oxygen (model units)
Explain what your data show
Use your recorded results to connect a claim to evidence and a scientific explanation.
Your work stays in this tab. Download your report before leaving or reloading.
Model example, assumptions & science background
Model of a clear explanation: “At 75% light and 20% CO₂ availability, this model produces 4 oxygen units. Increasing light to 100% still produces 4 units. The unchanged output supports CO₂ availability being the limiting input.” Use your own trials as evidence.
This deliberately simplified limiting-input rule is oxygen units = 20 × the smaller of the two relative settings, divided by 100. It is not a calibrated species-specific rate. The animation illustrates oxygen release; bubbles do not represent a real measurement interval. The model shows gross photosynthetic oxygen production and does not subtract oxygen consumed by respiration. It does not model temperature changes, water stress, damage, or realistic response curves. A maximum of 100 trials can be recorded.
