In today's lesson students will complete a lab to determine when photosynthesis and respiration occurs in algae. This lab helps students understand the connections between photosynthesis and respiration. This is the second day of a two day lesson. Here is an overview of what students will learn today.
Use the following assessment probe and ask students to predict when the processes of photosynthesis and respiration occur. The probe is designed to reveal whether students recognize that plants respire continuously.
During a class discussion, five students were talking about when plants carry out the processes of photosynthesis and respiration. Here is an except of what they said:
Mike: "Photosynthesis and respiration occur when it is light and when it is dark outside.
Rachel: "Photosynthesis occurs when the sun is out; respiration occurs at night."
George: "Photosynthesis occurs when it is light; respiration occurs when it is light and when it is dark."
Tina: "Photosynthesis occurs both when it is light and when it is dark; respiration only happens when it is dark."
Stacy: "Photosynthesis occurs in the day; plants don't carry out the process of respiration."
In your lab notebooks, make a +/- chart to determine what each student believe. With whom do you agree the most? Highlight that portion of the chart. Explain why you agree with that statement and not the others below the chart.
based on Keeley, Page. 2001. Light and Dark. Uncovering Student Ideas in Life Science. NSTA Press: Arlington, VA.
Using the lab proposal that students wrote yesterday, students will conduct an experiment to determine the effects of colored light on the rate of photosynthesis. After conducting the lab, students will input data into LoggerPro. Then they will use a regression line to calculate the rate of photosynthesis under different lighting conditions. Students will evaluate which type of light allows for the highest rate of photosynthesis. Students will explain their results at the bottom of their lab proposal.
In this activity, students will use algae as their model organism. They will measure the rate of respiration and photosynthesis by monitoring carbon dioxide and oxygen levels over time.
For this lab each student group will need the following equipment:
Collection of Data: Dark Chamber
Analysis of Data
Collection of Data: Light Chamber
Analysis of Data
Reporting the results
based on Redding, Kelly and David Mastermind. 2007. Photosynthesis and Respiration. Biology with Vernier. Vernier Software and Technology: Beaverton, OR
Have students record their responses in their lab notebooks.
Next have students revisit the assessment probe to which they responded at the beginning of the period. Have students modify their responses as necessary and support their new explanation with data from today's experiment. (Note: See student assessment probe revision.)