本文主要讲的是通过实验了解细胞呼吸和污染物的作用率的范文。文章通过进行的实验的过程探究观察碳水化合物发挥重要影响在细胞呼吸的作用和生产的二氧化碳。
The experiment of Cellular Respiration and The Effect of Pollutants on Its Rate has been done to explore some main problems with some purposes. The first aim is to let the students understand what the cellular respiration is. The second is to find what substance will have effects on the rate of cellar respiration reaction. The last is to find out how the pollutants affects cellular respiration. The key to the experiment is to observe carbohydrates that play an important role in the influence of cellular respiration and the production of the carbon dioxide.
As is known to all, the chemical equation of cellular respiration is ‘C6H12O6 / 6O2 6CO2 / 6H2O (/ ATPs)’, which is the core of the experiment. And meanwhile, the chemical equation is the fundamental theory of the experiment which gives us some instructions about the basic factors that affect the cellular respiration. From the equation, we can see clearly that the carbon dioxide is produced by the carbohydrates. A common sense is that carbon dioxide is lucid, so we observe indirectly the change in quality of carbon dioxide by observing the change of the liquid of the tube.
Introduction:
What the purpose of the experiment is to find out what cellular respiration is and get to known what substance influence cellular respiration. Meanwhile, we can also know the principle on basis of which the pollutants affect the rate of cellular respiration. Before we carry out the experiment, it’s necessary to understand some concepts involved in this experiment. The first concept is about cellular respiration. According to Wikipedia, cellular respiration is the set of metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. From the definition, we can conclude it as the same of the chemical equation mentioned above. What’s more, we know what we see in daily which is consist of cells mainly depends on cellular respiration to get energy to support their life. Moreover, nature is balanced in the field of atmosphere. We have known that carbon dioxide can be gotten from the cellular respiration. But carbon dioxide needs to be absorbed by some biology. According to reference 2, we know the plants can use photosynthesis to absorb carbon dioxide to produce oxygen which is necessary for the cellular respiration. So we can get that plants and animals live together and benefit from each other. When humans and animals breathe, they take in oxygen and give off carbon dioxide. This carbon dioxide is taken up by plants and oxygen is given off through photosynthesis. The process is balanced at any time unless the human beings destroy the environment.
The second concept which is important in this experiment is carbohydrate that is the most important energy material supporting biological life. According to reference 3, a carbohydrate is a large biological molecule, or macromolecule, consisting of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a hydrogen: oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n (where m could be different from n). From the definition, we easily find carbohydrate in our daily life, like sugar, glucose and etc. In our experiment, we choose sugar to represent carbohydrate, and yeast as a simple organism. With the purpose of finding out the effect of carbohydrate on cellular respiration, it’s necessary for us to do comparative experiments. So we organize two experiments of which, one is under the condition ‘yeast / water’, and another is under the condition ‘yeast / sugar / water’. The results of the experiment is gotten by observing the volume of the gas.
After we carry out the first part of our experiment, we pay more attention to find out the effect of pollutants on cellular respiration. It’s a common sense that pollution is a serious threat to our nature and life. We may hear air pollution, water pollution and etc. We may also hear some pollution which is bad to our breath, like toxic gas. What’s more, a number of respiratory diseases can afflict animals and plants. In the case of animals, the most common respiratory serious problems are asthma, pneumonia, lung cancer and emphysema. So in our second part of our experiment, many pollutants will be added to the equipment of the reaction to find how pollutants affect cellular respiration. In this part, the whole class is divide into 6 groups which focuses on one specific pollutant. For instance, our group focuses on vinegar. The key to determine the success of the experiment is to recording the date while observing the reaction. After we finish the record of the date, we can judge what we suppose before the experiment is right or not.
Method:
Material:
It is important for us to prepare for the correct materials for the experiment. In our two experiments, what we use contains: (1). 2 beakers, and each are 25mL (2). 2 Culture tube, clear, graduated 15mL, (3). One graduated cylinder, which is more than 15 mL (4). 1 wax marker (5). Pollutant simulated 3mL (isopropyl alcohol, vinegar, 10% salt solution, 5% baking soda solution, 1% bleach solution) (6). Sugar, granulated 7.5 ml (7). Spoon, measuring, 1.25mL (8). Plastic spoon (9). Vials, shells (10). Water tap 150ml for hot (11). Water tap 40 mL for warm (12). Small weight boat, and (13). Dry yeast for 7.5mL.
After we have finish the preparation, we carry out the experiment.
Procedure:
The experiment contains two parts, of which, one is part A which is used to explored the effect of the carbohydrate on cellular respiration, and another is used to find out the effect of pollutants on cellular respiration rate. The following text will be used to analyze the experiment in detail.
Part A: Effect of Carbohydrate:
Firstly, we prepared two 15mL test tubes, two 4-dram vials, and two 25mL beakers. Secondly, we used wax marker to mark culture tube and beaker into 1 and 2. In beaker 1, we measured 1.25 dry active yeast by 1.25ml measuring spoon. At the same time, we added 1.25 mL granulated sugar into beaker 2, and also put 1.25mL into beaker 1. Using graduated cylinder to measure 13mL warm. Next step is to mix all staffs thoroughly. After this step, we need to quickly invert vial 1, and then culture tube 1 against the “bottom” of vial 1. Vial 2 does the same things. The following step is to calculate time, and record the phenomena of each minute. The total time of this experiment is 10 minute. We record all collected data in the lab form, and then we clean up the beakers, tubes, and vials. After finished this, we start to prepare out next experiment.
Part B: Effect of Pollutants:
The first step of this experiment was to prepare all the materials that we needed to do it. The following step was to measure 1.25mL dry active yeast and 1.25mL granulated sugar. And then put all things into the 25mL beaker. Using graduated cylinder measures 20mL, and mixes sugar, water, and yeast together. Also, we needed to add simulated pollutants. This is an important to step. Our professor separated our class into 6 groups, and each group focused on one pollutant. Our group mainly explored how vinegar will influence cellular respiration. We added 5 ml vinegar, and then obverse what happened during 10 minute. The last step is to record the data about what happened in each minute. The most important thing we need to do is to collected other group’s data from part A and part B, and the compared the data.
Results:
Part A: Effect of Carbohydrate:
We use table and chart to show the results of the experiment. From the results, we can easily find which is at the higher rate in cellular respiration. From the table or chart, we can easily get that yeast / water produces no carbon dioxide, while yeast / water / sugar produces carbon dioxide. What’s more, the quality of carbon dioxide is increasing with the time.
Table 1. Gas (CO2) volume (mL) at 1 minute intervals for 10 minutes
Tube Gas Volume(mL) in tube at time(min)
NO. Materials 0 1 2 3 4 5 6 7 8 9 10
1 yeast / water 7 7 7 7 7 7 7 7 7 7 7
2 yeast/ water/ sugar 5 5 5.3 5.5 5.9 6 7.2 8.2 9.1 9.2 9.5
Chart 1. Gas (CO2) volume (mL) at 1 minute intervals for 10 minutes
Part B: Effect of Pollutants:
We also plot the figure of the results from 6 groups. It’s easy to get that pollutant influences cellular respiration greatly. For instance, the blue line which represents the quality of carbon dioxide under baking soda soln. is changing greatly than the yellow line which represents the quality of carbon dioxide under salt solution.
Chart2. Gas (CO2) volume (ml) at 1 minute intervals for 10 minutes for 6 groups
Discussion:
We have finish the experiment, and get together to discuss some details of the experiment. Before we do this experiment, we have supposed that a simple organism will have a higher rate of cellular respiration in the presence of a source of carbohydrate than that in the absence of a source of carbohydrate. The result in part A gives us the verification of our supposition. The result lets us understand why carbohydrate is a main kind of energy material.
Another supposition is that pollutants influence the rate of cellular respiration. From the result of Part B, we can see it clearly that pollutants affect the rate of cellular respiration. From the results of Part B, some groups don’t produce carbon dioxide, such as our group, whose pollutant is vinegar.
Apart from the factors we consider in this experiment, I think some other factors will affect the rate of cellular respiration, such as the content of oxygen, the environment temperature and etc. If we want to get more precise results, I think, we need to design better experiment.
Last but not least, cellular respiration plays an important role in our life. We should keep it free from pollution. We should struggle with those who produce pollution which threatens our environment. It is our responsibility but also our duty.
Reference
[1]Click the following link to get the definition of cellular respiration
[2]Zelitch, I. (Ed.). (2017). Photosynthesis, photorespiration, and plant productivity. Elsevier.
[3]Western Kentucky University (May 29, 2017). "WKU BIO 113 Carbohydrates". wku.edu.
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