Photosynthesis Rate Challenge: Optimizing Glucose Production

NGSS Alignment

• Performance Expectation: HS-LS1-5 - Use a model to illustrate how photosynthesis transforms light energy into stored chemical energy.
• Science and Engineering Practice: Developing and Using Models
• Disciplinary Core Idea: LS1.C - Organization for Matter and Energy Flow in Organisms
• Crosscutting Concept: Energy and Matter

The Scenario: AeroGrow Startup

You have just been hired as a Lead Agricultural Scientist for AeroGrow, a new vertical farming startup in New Britain, Connecticut. AeroGrow specializes in “Hydro-Crops”—aquatic plants that can be grown in large indoor tanks to provide sustainable food sources for urban areas.

Your first mission is to optimize the growth of Elodea canadensis, a hardy aquatic plant. To maximize profit, AeroGrow needs to produce as much glucose (chemical energy) as possible while minimizing the electrical cost of lights.

Simulation Link: Photosynthesis Rate Lab

Phase 1: Initial Exploration

Launch the simulation and observe the plant in the tank.

1. Observable Phenomena: What do you see rising from the plant? What do these “bubbles” consist of, and why are they a good indicator of the photosynthesis rate?
2. Energy Source: Move the lamp closer to the tank (increase Light Intensity). Describe what happens to the bubble rate. How does this demonstrate a transformation of energy?

Phase 2: Identifying Limiting Factors

In a vertical farm, you must balance multiple variables. If you increase one variable (like light) but the plant can’t keep up because of another variable (like CO2), you are wasting money on electricity.

1. Controlled Experiment (Light): Set Temperature to 25°C and CO2 Concentration to 500 ppm.
   • Vary the Light Intensity from 0 to 100 in increments of 10.
   • Record the Current Rate for each setting.
   • The Saturation Point: At what Light Intensity does the rate of oxygen production stop increasing? Why do you think this happens?
2. Controlled Experiment (CO2): Now, set Light Intensity to 100 and Temperature to 25°C.
   • Vary the CO2 Concentration from 0 to 1000 ppm.
   • Identify the concentration where the plant reaches its maximum rate.

Phase 3: The Wavelength Mystery

Plants aren’t equally efficient with all types of light.

1. Filter Test: Change the Light Wavelength (color filter). Use the simulation to determine which color (Red, Green, Blue, or White) is:
   • Most Efficient: ______
   • Least Efficient: ______
2. Inquiry: Why do you think Green light is so much less effective for photosynthesis? (Hint: Look at the color of the plant’s leaves. What does a green color tell us about how the leaf interacts with green light?)

Phase 4: Synthesis & Modeling

1. Construct a Model: Based on your investigations, draw or describe a model that illustrates the flow of Energy and Matter in this system. Your model must include:
   • Inputs: Solar energy (light), Carbon Dioxide ($CO_2$), and Water ($H_2O$).
   • Outputs: Oxygen ($O_2$) and Chemical Energy (Glucose).
   • Transformation: Briefly explain how the energy from the “Input” side ends up in the “Output” side.
2. The AeroGrow Recommendation: Write a brief (3-4 sentence) memo to your supervisor recommending the “Optimal Growth Profile” (Intensity, CO2, and Color) for AeroGrow’s tanks. Use evidence from the simulation to justify why this profile is the most efficient choice for maximizing glucose production.