Introduction

The eukaryotic organisms in an environment operate under specific conditions with specific functionality. This functionality is determined by the triplet code sequences in the deoxyribose nucleic acid in the cellular nucleus (deep within the cellular plasma membrane). The triplet code sequences are used to build proteins, and more specifically, enzymes and hormones. Enzymes control all of the chemical reactions that occur within the cellular nucleic boundary—no random reactions occur. The enzymes lower the activation energy for chemical reactions in specific metabolic pathways. This causes organisms to produce entropy and will be further discussed with respect to the trophic pyramids of habitats.

Metabolic pathways are consistent sequences of chemical reactions that can be repeated throughout many different cells. These pathways both utilize molecules and build new molecules, sometimes using condensation reactions, sometimes through hydrolysis, etc. One of these specific metabolic pathways is the one in the lysosomes that occurs as a result of fatty acid digestion. A byproduct of lysosomic digestion of fatty acids is hydrogen peroxide, and in order to counteract the poisonous molecule (H₂O₂) the enzyme catalase is used to catalyze the decay of the poison (AP Lab#2). The catalase-reactions are an excellent example of just one of the many thousands of metabolic pathways that occur in organisms throughout the environment.

The chemical reactions inside organisms throughout some given population determines their homeostatic capabilities, or ability to react to environment changes and regulate internal conditions, keeping to our definition of life. The resources used and the way that they are used through metabolic pathways is directly related to other local organisms including the abiotic and biotic factors of the environment. This all leads back to the trophic pyramid, or the relationships between primary producers, secondary producers, consumers, secondary consumers, and top consumers. Through a thermodynamic understanding of the ecosystem, the relationships between organisms can be understood: the relationships between organisms can be further understood by studying the metabolic pathways of the organisms as well due to the fact that enzymes lower the activation energy required for metabolic activity in the cell.

One special metabolic pathway that was studied in this lab was that of photosynthesis and chemosynthesis in protists, bacteria, and other organisms of the atrium water used. The process of photosynthesis takes CO₂ from the air and then takes the carbon atom and puts it into one glucose molecule, which is then processed further in cellular respiration pathways (the Calvin cycle, the Krebs cycle, etc.). That slightly more complicated molecule (glucose) paves the way for more complicated chemical compositions, such as for proteins, lipids, nucleic acids, and so on. The complicated molecules are diffused throughout the ecosystems once heterotrophic organisms consume the protists, bacteria, plants, and other autotrophic organisms.

Coincidentally, had we no knowledge of the existence of organisms in the local atrium, this would have been an excellent experiment to show that despite no materials escaping there was definitely a change in the type of material present in each of the bottles (the specifics are explained later). This is all because of the chemical pathways in each organisms have specific “inputs” and specific “outputs”.

Although the lab packet specifically suggested other forms of hypothesis, my hypothesis (that will be explained later) is the following: once tracked, the ratio of atoms remaining in the water will match the ratio of atoms in specific molecular configurations due to the steps in metabolic pathways, specifically, photosynthesis. More advanced approaches to experiments with this hypothesis could be done using radioactive isotopes for atomic tracking (see discussion in the conclusion).

Particular vocabulary follows:

Materials, Methods, and Objectives

In order to implement knowledge and concepts of population ecology relative to evolutionary biology, the objectives of this particular lab included an improved understanding of how to measure primary productivity based on changes in dissolved oxygen in a controlled experiment, and an ability to investigate the effects of changing light intensity on primary productivity in a controlled experiment. If the dissolved oxygen in the dark bottle is greater than that of the light bottle, then there are no organisms using the dissolved oxygen, and the data supports this (though does not provide absolute certainty of this).

The subject studied was primary productivity and the measurement of primary productivity, the identification of amounts of dissolved oxygen, and controlling the amount of light given to a specific microenvironment to test for changes in dissolved oxygen and to calculate primary productivity. Our knowledge of dissolved oxygen tells us that in order to conduct an applicable experiment to expand our scientific knowledge, some sort of simulated environment is needed. That is the reason why sealable canisters of water (bottles, beakers, whatever can be found laying around) were completely filled with water without any sort of air bubbles visible, and then testing this sample initially for dissolved oxygen.

To test for the effects of light on photosynthesis, take the bottles and wrap them with different amount of net wiring that would filter out light. Leave the bottles under some light source over the period of 12 hours. Test the remaining levels of dissolved oxygen and record these figures. The method for testing for dissolved oxygen that we used is known as the Winkler test for dissolved oxygen.

The Winkler test for dissolved oxygen involves manganese(II) sulfate solution (48% concentration), potassium iodide (15% concentration) in potassium hydroxide (70% concentration), those fresh water samples, gloves, and safety glasses when carrying out the test. To continue with the test on the second stage, one needs sulfuric acid (50% concentration), sodium thiosulfate (0.31% concentration), starch solution (0.1% concentration), a Burette and Burette stand, pipette, flask, and filter paper. The procedure for the Winkler test is detailed in Winkler, 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Essentially, this method allows one to determine the amount of dissolved oxygen due to knowledge of the reactions that take place when the concentrated solutions are added to the fresh water samples.

There's two important points to the test. The first important point is using that sequence of sulfemic acids and so on to set the sample. Once we have set the sample, we have locked in the series of events that allows us to read the dissolve oxygen. The second importance is the test that shows us the dissolved oxygen. Chemical reagents play an important role in this experiment. When we add an indicator solution, as a test reactant, the indicator solution is whatever is in the bottle, and the test reagent is whatever you are dropping into the solution. There are two indications of a chemical reaction, and if you get either one of those, you know there is a chemical reaction. If it forms a precipitate (cloudy stuff forms in test solution), or if it changes color, then a chemical reaction occurs. We did that twice to determine the amount of dissolved oxygen. Once we got the ppm, then we have to know the concentration of the dissolved oxygen, which is detailed and analyzed in later sections of this lab report relative to graphs of changes and trends.

It is important in understanding the reason for using fresh water for the specimen / sample in this experiment. Although this experiment did not include tests for organic processes present in the sample, it could be shown that (our) sink-water does not contain photosynthetic organisms whereas the atrium water was filled with all sorts of exotic organisms as they were introduced into the environment from student projects (especially the protist project where students collected organisms from pond waters around the local biogeographic areas and later released the organisms into that same atrium). The reliability of our results is more assured given this strongly populated pond from which samples were taken.

Data

The following denotes the parts per million required to change the color of the sample to indicate that all dissolved oxygen has been chemically dealt with, for each of the bottles tested. The first word indicates which sample, where initial represents the basis for the day's experiment, the dark bottle was not exposed to light, and the rest are the percentage of light getting through to the bottle's contents. The three numbers following on each of those lines indicates the amount of solution required for each sample (see the procedures for the Winkler test for dissolved oxygen). The final number is the class average. Following the class average are notes that must be retained in addressing these data.

“Data Set A”

Initial - 5 ppm, 7.4 ppm, 8.2 ppm = 6.8 ppm

Dark (0%) - 3 ppm, 1.8 ppm, 4.2 ppm = 3 ppm

100% - 2 ppm, 5.5 ppm, 6.6 ppm = 4.7 ppm

65% - 1 ppm, 2 ppm, 5.4 ppm = 2.8 ppm

25% - 1 ppm, 2.2 ppm, 6.8 ppm = 3.3 ppm

10% - 1 ppm, 2.2 ppm, 5.8 ppm = 3 ppm

2%- 1 ppm, 1.8 ppm, 5.2 ppm = 2.6 ppm

“Data Set B”

Table 12.1

24, 3.6, 4.4, 6.8, 6.2, 36, 43

20, 6.4, 6.8, 60, 55

6.0, 6.2, 55, 63

“Data Set C”

Table 12.3

For the initial bottle: 7.7 ppm

For the dark bottle: 1.5 ppm

For the 100% bottle: 3.5 ppm

For the 65% bottle: 1.7 ppm

For the 25% bottle: 1.6 ppm

For the 10% bottle: 1.7 ppm

For the 2% bottle: 1.1 ppm

Analysis and Discussion

The data is not entirely accurate because of the many errors that were introduced. There was no way to tell if there was any “air bubbles” left in the bottle when attaining the samples. The bottles could have had many tiny air bubbles at the top underneath the cap away from view. The sample of water within the bottle was exposed to the open air before doing the first part of the Winkler test. The powdered substance was not measured exactly when putting it into the sample to “set the sample”.

The chemical solutions were squirted carelessly and exact measurements were not easily taken. However, in general, the class averages seem to agree with our data in the first place, suggesting that either (1) there are trends in percent error or (2) everyone was actually doing this correctly. The second result is unlikely because the samples were not necessarily dealt with properly, as they were not under the light source for the entirety of the night.

Conclusions

It is interesting to note that in data set “A” the greater dissolved oxygen content of the 100% light bottle than of the other bottles, suggesting that in this experiment the bottle with the greater light ended up with (on average) the more dissolved oxygen. This is likely because of the microorganisms acting in the environment with their photosynthetic processes that takes CO₂ and light and water and results in glucose and O₂. Another hypothesis to deal with might be the exploration of whether or not increasing the surface area of plasma membranes increases the total amount of photosynthesized dissolved oxygen in the environment.

Notes and so on:

Cover respiration and photosynthesis relative to the dissolved oxygen and aquatic primary productivity lab, relative to what we have been talking about in class. Address how primary productivity is an example of the ecological concepts that we have been talking about for the last week in class.

What are the objectives? The objectives are what we are actually going to do in our lab. We are trying to use our understandings and readings of dissolved oxygen to draw conclusions about primary productivity. The objectives are the things that we are trying to learn. The objectives may or may not be relevant to our earlier discussions—that's what we're doing the lab for. Use the determinations to draw conclusions about primary productivity, which we have already related to our previous concepts.

The pertinent vocabulary is quite important. One of the concepts is primary productivity, photosynthesis, respiration, and those are some words that you need to address. The background information for the lab is important. Circle and/or highlight and/or underline, and indicate to yourself what sort of words are new to you. Just make sure you define the words—there is no necessary format, it's just the depth that you have gone to, and the pains that you have gone to in order to explain the vocabulary.

The materials and methods is the toughest thing that you have to deal with. Do not spend much time on the procedures. Why did we use what we used? What did we use? Why did we use naturally occurring pond water? Why not from the sink? Because there would not be as many living things. The living things are an important part of the experiment. Why? We were dealing with living organisms in this lab and this creates some variables and you must figure out why those are important.

The study of water quality—what is the word there? What was the most important part of the Winkler method? What was the most important part? Not the procedure. There's two important points to the test. The first important point is using that sequence of sulfemic acids and so on to set the sample. Once we have set the sample, we have locked in the series of events that allows us to read the dissolve oxygen. The second importance is the test that shows us the dissolved oxygen. Talk about how chemical reagents work. When we add an indicator solution, as a test reactant, … The indicator solution is whatever is in the bottle, and the test reagent is whatever you are dropping into the solution. There are two indications of a chemical reaction, and if you get either one of those, you know there is a chemical reaction. If it forms a precipitate (cloudy stuff forms in test solution), or if it changes color, then a chemical reaction occurs. We did that twice to determine the amount of dissolved oxygen. Once we got the ppm, then we have to know the concentration of the dissolved oxygen - not how you got it (with the ruler on the nomograph). Why is that percentage (percent saturation) important?

The hypothesis can be the very first thing that you do in the materials and methods section of the lab report. Tell how everything that we have done, why, how, etc., how does that all relate to your hypothesis? If the dissolved oxygen in the dark bottle is greater than that of the light bottle, then there are no organisms using the dissolved oxygen, and that's something that we can support.

The data is the data - let's talk about it. Address the reasons that the warm bucket lost a great deal of its dissolved oxygen. This is why your sample bottles did not turn yellow, because there wasn't any oxygen to start it. Make a simple observation about the left (warm) bucket. It was the warm bucket one. You will have to address this. The light seems to be more over the warm bucket. The light did not get switched off for these (the light was however switched off for the seven-bottle stuff). Do you think heterotrophic organisms are going to multiply more rapidly in a warm or cold environment?

The fact that they would has something to do with dissolved oxygen.

Look at table 12.1. The left-hand column says temperature, lab group DO, lab group % DO saturation, class mean % DO saturation.

Know how to use a nomograph.

The initial bottle (from 10/3) is your control, it's before we manipulated any variable, right? Make sure you have the temperature of that bottle noted - it should have been about 23 degrees Celsius on that particular day. The temperature of this room is generally 23 degrees Celsius (if you ever forget to take the measurements on temperature). The initial bottle is your control. The light bottles are the bottles that we either did or did not wrap the screens around. Each of the light bottles is identified by the percentage of light that we allowed in (by wrapping more and more screens on). There was a 100% bottle all the way down to a 0% bottle that was in aluminum foil.

Get a class average for each of the seven bottles, in terms of ppm, for the initial bottle, and for the dark bottle. Then, when you continue with the experiment, to continue figuring out things such as productivity, use the class averages instead of the actual data. This makes your data better once we do the averages. We are going to get a class average for the initial bottle, for the dark bottle, for the 100%, 65%, 25%, 10%, and 2%.

Initial is not the same as your light bottle. We filled up the initial bottle on Tuesday (10/3).

The following denotes the parts per million required to change the color of the sample to indicate that all dissolved oxygen has been chemically dealt with, for each of the bottles tested. The first word indicates which sample, where initial represents the basis for the day's experiment, the dark bottle was not exposed to light, and the rest are the percentage of light getting through to the bottle's contents. The three numbers following on each of those lines indicates the amount of solution required for each sample (see the procedures for the Winkler test for dissolved oxygen). The final number is the class average. Following the class average are notes that must be retained in addressing these data.

Initial - 5, 7.4, 8.2 = 6.8 (this last number is the average)

Dark - 3, 1.8, 4.2 = 3

100% - 2, 5.5, 6.6 = 4. 7(15 hours of light? Maybe not enough. Everybody has had the same.)

65% - 1, 2, 5.4 = 2.8

25% - 1, 2.2, 6.8 = 3.3

10% - 1, 2.2, 5.8 = 3

2%- 1, 1.8, 5.2 ppm = 2.6

Table 12.1

24, 3.6, 4.4, 6.8, 6.2, 36, 43

20, 6.4, 6.8, 60, 55

6.0, 6.2, 55, 63

Table 12.3

Class average (ppm) for the initial bottle was: 7.7 ppm

For the dark bottle: 1.5

For the 100% bottle: 3.5

For the 65% bottle: 1.7 ppm

For the 25% bottle: 1.6 ppm

For the 10% bottle: 1.7 ppm

For the 2% bottle: 1.1 ppm

http://en.wikipedia.org/w/index.php?title=Primary_production&oldid=77737509

Bryan Bishop Dissolved Oxygen Lab Report (#12) October, 02006