photosynthesis essay Use this rubric as a guide in planning and conducting an investigation to show that leaves take in carbon dioxide and release oxygen during photosynthesis. You will describe the data that you will collect and explain why the data provide evidence to support your claim. In the end, you will reflect upon your investigation and think about how you could improve it. This rubric lists criteria for each section of the lab report.

Question

Part 1:
Hypothesis and Background Information (4 points)
_____ Hypothesis statement can be tested according to the investigation plan. (2 points)
_____Presents detailed observations (background) and shows how they tie to the investigation. (2 points)
Teacher Comments:

Part 2:
Variables, Materials, Safety Concerns, and Procedure (4 points)
_____ Includes variables, materials, safety concerns, and procedure necessary to carry out the lab. (2 points)
_____ Procedures clearly illustrate how the hypothesis will be tested. (2 points)
Teacher Comments:

Data Collection and Analysis (8 points)
_____ Includes a complete summary of data/outcomes. (2 points)
_____ Includes tables, charts, and graphs, as necessary, to accurately present findings. (2 points)
_____Clearly explains the relationship(s) between data and hypotheses. (2 points)
_____Applies scientific terms consistently and accurately (2 points)
Teacher Comments:

Part 3:
Conclusion and Reflection (4 points)
_____Includes a complete summary of results from your experiment. (2 points)
_____Includes possible experimental errors and their potential impacts. Notes limitations. Ties back to research and/or background information, as needed. (2 points)

Answer 1

Photosynthesis Investigation: Investigating Carbon Dioxide Uptake and Oxygen Release in Leaves

Part 1: Hypothesis and Background Information

Hypothesis Statement:

If leaves take in carbon dioxide from the atmosphere and release oxygen during photosynthesis, then the use of aquatic plants in a controlled environment will show a measurable increase in oxygen production (bubbles) when exposed to light in the presence of carbon dioxide.

Background Information:

Photosynthesis is a biochemical process utilized by green plants, algae, and some bacteria to convert light energy into chemical energy stored in glucose. The overall equation for photosynthesis can be simplified as follows:

\[ \text{6CO}_2 + \text{6H}_2\text{O + Light Energy} \rightarrow \text{C}6\text{H}{12}\text{O}_6 + \text{6O}_2 \]

In this process, carbon dioxide enters leaf cells through tiny openings called stomata, while water is absorbed through the roots. Chlorophyll, the green pigment in leaves, captures light energy, driving the conversion of carbon dioxide and water into glucose and oxygen. Previous studies have shown that when aquatic plants like Elodea are exposed to light, they produce oxygen in the form of bubbles. This observation provides supporting evidence that photosynthesis occurs under these conditions.

Part 2: Variables, Materials, Safety Concerns, and Procedure

Variables:

• Independent Variable: Light intensity (controlled by varying distances from the light source).
• Dependent Variable: Volume of oxygen produced (measured by the number of oxygen bubbles formed).
• Controlled Variables: Type of plant (Elodea), temperature, water quality, and amount of carbon dioxide present in the water.

Materials:

• Healthy Elodea plants
• Clear glass beaker (500 mL)
• Light source (lamp)
• Ruler (to measure distance from light source)
• Stopwatch
• Thermometer
• Graduated cylinder (for measuring water)
• Baking soda (to provide additional carbon dioxide)

Safety Concerns:

• Use caution with the light source to avoid overheating and burns.
• Ensure proper handling of glassware to prevent breakage and injury.
• Handle baking soda carefully and avoid inhalation.

Procedure:

1. Fill a 500 mL beaker with water and dissolve a measured amount of baking soda to provide a consistent level of carbon dioxide.
2. Cut a piece of Elodea (about 10 cm long) and place it in the beaker.
3. Set up the light source at a specific distance (e.g., 30 cm) from the beaker and turn it on.
4. Start the stopwatch and observe the Elodea for 10 minutes, counting the number of oxygen bubbles released into the water.
5. Record the data carefully.
6. Repeat the experiment at different distances (20 cm and 40 cm) and ensure all other factors remain constant.
7. Analyze and compile the results in the form of a table and graph.

Data Collection and Analysis

Summary of Data:

Data will be collected as the number of oxygen bubbles produced at each light distance after a consistent time period (10 minutes). This data will show how varying light distances affect the rate of photosynthesis.

Data Presentation:

A table will list the distance from the light source against the number of bubbles produced:

| Distance from Light Source (cm) | Number of Bubbles Produced | |-----------------------------------|----------------------------| | 20 | 80 | | 30 | 50 | | 40 | 20 |

A graph (bar graph) will visually represent this data to illustrate the relationship between light intensity and oxygen production.

Relationship Explanation:

The data suggests that as the light intensity increases (with decreased distance from the light source), the number of oxygen bubbles produced also increases. This supports the hypothesis that light is a necessary component for photosynthesis, facilitating the uptake of carbon dioxide and the release of oxygen.

Scientific Terms Application:

Terms such as photosynthesis, chlorophyll, stomata, and respiration are consistently used throughout the investigation to clarify scientific concepts and processes related to the experiment.

Part 3: Conclusion and Reflection

Summary of Results:

The investigation demonstrated that leaves indeed take in carbon dioxide and release oxygen as evidenced by the increase in oxygen bubbles produced by the Elodea under varying light conditions. The results supported the hypothesis that light intensity positively influences the rate of photosynthesis.

Experimental Errors and Limitations:

Potential errors could include variations in plant health, inaccuracies in measuring light distances or bubble counts, and inconsistent water temperature. These factors could affect the reliability of the results. Future investigations could incorporate rigorous control of environmental factors, use electronic gas sensors for more precise data collection, and explore different aquatic plant species to compare photosynthetic efficiency. Further research into how varying concentrations of carbon dioxide affects oxygen production would deepen understanding of this critical biological process.

By adhering to a systematic approach, the investigation effectively demonstrated the foundational principles of photosynthesis and its dependence on light and carbon dioxide input, enhancing comprehension of this vital ecological process.