Cellular Respiration, Lab Report Example

Objective of the research

To find out whether the big goldfish or the little goldfish will produce more CO₂ if contained in the same amount of water.

Hypothesis

The big fish will produces more CO₂ because it has a larger body mass.

Introduction

All living organisms on the Earth require energy to maintain various processes connected with their lives. “Cellular respiration is the process by which the chemical energy of “food” molecules is released and partially captured” (Pearson Education 2010). Aerobic organisms have oxygen-based metabolism, which means that when exposed to aerobic respiration they will use O₂ (oxygen) and produce CO₂ (carbon dioxide).

Heterotrophs

Heterotrophs are single or multi-celled organisms that cannot capture the energy of the sun directly through the process of photosynthesis. As a result heterotrophs are considered to be consumers in the food chain. In the following experiment this specific fact has an important meaning. Goldfish is an aerobic heterotroph, which cannot produce O₂. When put into the water or any other substance, goldfish will use O₂ instead to stay alive. As a result the amount of O₂ in the water will decrease and the amount of CO₂ will increase depending on the time the fish is in the water.

Cellular Respiration

Cellular respiration is a combination of metabolic reactions that take place in every cell of the organism, which converts biochemical energy (energy contained in food) into the energy currency of the living organism – Adenosine Triphosphate (ATP) and waste products.

C₆H₁₂O₆ + 6O₂ ? 6CO₂ + 6H₂O + Energy (36 or 38 ATP molecules)

The formula shown above is another milestone of the following experiment. A molecule of glucose combined with oxygen results in release of carbon dioxide, water, and energy. The arrow in this reaction is a substitute for various complicated reactions that occur at the cellular level.

Phenolphalein

Phenolphalein (C20H14O4) is the chemical compound that changes its color in strongly acidic and basic environment. As a result of cellular respiration some amount of CO₂ will be released into water.

CO₂ + H₂O ? H₂CO₃ (carbonic acid)

When carbonic acid is neutralized by NaOH (caustic soda), phenolphalein will remain colorless, since the environment will be neutral or nearly neutral.

H₂CO₃ + 2 NaOH ? Na₂CO₃ + 2 H₂O

However, if the amount of H₂CO₃ is less than the amount of NaOH, then by adding some amount of phenolphalein researcher may obtain basic environment in the water. In this case the water will change its color to pink.

Experiment

Gather all required materials and put on protective eyewear and gloves for safety. Add 200 ml of distilled water to three beakers, place tape on each beaker, and label them “Big Fish”, “Little Fish”, and “ No Fish”. Scoop one 1-inch fish, and one 2-inch fish from the tank, place them in the appropriate beakers. Do not put anything into the beaker marked as “No Fish”. Keep fish in the beakers for thirty minutes and record activity every five minutes. After the time is over, keep the water and return the fish to the aquarium tank. Add five drops of the pH indicator into each beaker slowly add 0.02 drops of NaOH (caustic soda) to the beaker labeled ‘No Fish’. Stir the solution with a glass stirring-rod after adding each drop until a faint pink color is obtained.  Add the same amount of NaOH and pH to the “Big Fish” and “Little Fish” beakers until the SAME pink color is obtained.  Record the number of drops it took to achieve the same color.  Calculate the amount of CO₂ neutralized by the NaOH by the difference in the number of drops of NaOH in each.

Results

The number of drops in the beaker with big fish is less than in the beaker with little one. The difference in drops from control group is 4 and 44 drops for “Big Fish” and “Small Fish” beakers accordingly. This means that the amount of CO₂ produced in the “Small Fish” beaker is a lot bigger than in “Big Fish” beaker – 1.98 ml and 0.18 ml.

Table 1. Results.

The chart “Amount of Carbon Dioxide Produced” shows the relation of amount of CO₂ produced by the bigger fish to that of the smaller one. The difference between the results equals 0.8 ml.

Conclusion

Hypothesis that bigger fish produces more carbon dioxide because it has larger body mass is wrong. The experiment has shown that smaller fish produce a lot more carbon dioxide than the bigger fish does. Smaller fish produces more carbon dioxide due to the higher metabolism, which can be associated with the age of the fish and the amount of energy smaller fish needs maintain its life. The conducted research is not accurate and may contain several errors in it. Though the amount and structure of water is the same, researchers should check if both fish eat the same food and are healthy. Additionally, more accurate methods should be used to determine the amount of carbon dioxide in each beaker.

Works Cited

Pearson Education, 2010. Cell Respiration. Introduction. BioCoach Activity. Novermber 13, 2010. http:/ /www.phschool.com/science/biology_place/biocoach/cellresp/intro.html.