Natural Systems; Wankel
The Smoky Situation
Final Lab Packet
Does tobacco smoke effect the growth of a plant? Our purpose is to discover whether or not tobacco smoke inhibits the development of plants. It is proven that long term exposure to tobacco smoke has a very unhealthy and negative effect on humans, which leads us to believe that tobacco smoke will have the same effects on plants. If in fact the plants are negatively effected by the smoke, we should be able to observe a reduced rate of plant growth compared to a plant that is not exposed to smoke. Furthermore, the smoke will prevent the growth of new healthier leaves, thus lowering the total leaf count.
We hypothesize that repeated exposure to smoke over an extended period of time will slowly stunt the growth of the plants.
What to accomplish
We hope to effectively take data that will either prove or disprove our hypothesis that tobacco smoke stunts the growth of plants. We then hope to derive scientific reasons for our acceptance or rejection of the hypothesis. Hopefully, our research can be used to effectively educate others about the overall effects and contents of tobacco smoke. If for some reason we find evidence enough to reject our hypothesis, the evidence that tobacco has no effect or beneficial effects on plants could help to change the public’s overall negative attitude about tobacco. Otherwise, our data will support the argument that smoking is almost a completely harmful habit. If our hypothesis is correct, it gives another valid reason to prevent the spread of second hand smoke: plants need fresh air too!
Tobacco smoke has been the topic of much attention from the media in resent years. America’s increasingly large health conscious population has eaten up any and all evidence that tobacco smoke is detrimental to one’s health. We have decided to further test the effects of tobacco smoke in order to either support or contradict popular findings that tobacco smoke is consistently harmful. If we reject our hypothesis that tobacco smoke is harmful to plants, this would be very surprising to the average American.
We researched and discovered that there have been numerous experiments on smoking, plants and pollution. According to one study done by NASA plants take pollutants out of the air throughout the tiny openings in their leaves. Concluding that plant leaves, roots, and soil bacteria are all important in absorbing small amounts potentially dangerous or harmful gases. The study consisted of testing houseplants in an indoor environment. By proving in this study that plants do absorb air pollution, it therefore follows that plants are definitely either positively or negatively effected by pollutants in their surrounding atmosphere.
We came across another study by a ninth grader from San Diego, that directly tested cigarette smoke on plants, which is quite similar to our proposed experiment. The results in the ninth grader’s study were a bit surprising. In her results the plants that were exposed to tobacco smoke grew taller than the control group. One explanation for these results offered by Cyndy Galloway, a published biologist with postings on the Internet concludes that Carbon Monoxide from the cigarette smoke could increase photosynthesis.
We also found some information about second hand smoke compared to first hand smoke. The end of a burning cigarette releasing second hand smoke into the air has more particles that are smaller and more harmful than the smoke inhaled through the cigarette and filter directly to the smoker. Because of the second hand smoke particles’ small sizes, they can go deeper into the lung, thus creating more damage. This is relevant to our proposed experiment because the smoke that we will be testing will be from the end of a burning cigarette. Using the information in the second-hand smoke study, we can assume that the smoke we will be testing is just as toxically potent, if not more so, than first-hand smoke.
We are testing ten bean plants. We had planted forty, but only two sprouted. Therefore, we used eight plants from another lab group, The Wonderwheel. We will set the situation up with a cigarette and ashtray in an terrarium.
12 bean plants time measurement device
12 pots water and container
1 terrarium Marlboro Red cigarettes
1 cigarette lighter (or matches) 1 ashtray
1 ruler soil
1) Put bean plants in stable growth environment. We are using the greenhouse in Boyd Hall to keep our plants when they are not being tested. Whatever the space used should, as Boyd’s greenhouse does, provide ample amount of sunlight and a constant warm temperature. An area on a table in the greenhouse no greater than three square feet has provided enough room for both plant and material storage. The plants should be initially watered twice to moisten the dry soil in order for the plants to germinate. (See step 8 for continual watering instructions)
2) Mark the ten plant pots. Five plant pots are marked “Test” and five are marked “Control”. Each plant pot has an individual sub-labeling number. Each test and control plant pot is numbered one through five.
3) We planted the plants in separate containers. The soil, Scotts Metro Mix 360, in each pot was filled to an inch below the top of each pot.
4) Record initial plant height before testing begins. Using a ruler as a measurement device, place the ruler at the base of the plant at the exact level of the soil. Then, holding the ruler against the main stem of the plant, measure the height of the plant to the top of the stem while holding it upright. If the stem is crooked, hold a piece of string flush against the stem from the base to the top. Then, mark the length and measure. If there are leaves above the stem, do not count them in the height measurement. Record data on the data sheet.
5) Record initial number of leaves. Count the number of leaves on the plant and record data. Then make notes about the plant’s overall appearance in a qualitative data section of the data sheet. Pay special attention to plants position (Does it droop over when standing on it’s own?) and the overall color and condition of the leaves.
6) Set up test procedure. Take the plants labeled test to a test location outside of the greenhouse, in Boyd Hall. This should be an area free of moisture and severe weather conditions. This should also be an environment where the smoke created during the experiment will not bother others or violate school building policies. Place the test plants in the aquarium, covering with the lid. Also place the ashtray near the test plants under the aquarium.
7) Expose plants to smoke. Light all six cigarettes. Then, briefly lift the terrarium and put the cigarettes on the ashtray. Then start the stopwatch or note the time on a clock and place the aquarium back over the plants and ashtray.
If the cigarettes go out, lift the lid momentarily and re- lite the cigarette attempting not to allow too much smoke escape the enclosed area. If this occurs, make a note of this occurrence on the data sheet. Let both cigarettes burn until all tobacco has been burned. When only the filters are left, take them out and drop them into the container of water and let the smoke circulate for the remainder of the half hour.
Record data on test data sheet. Then take plants and all materials back to the greenhouse. Clean ashtray and place plants and materials back in storage area.
8) Once the bean plants have germinated, into week two, we then water them according to their growth rate. The older they get, the more water they require. Initially, we water them every three days, at Harry’s request. Fill water container with tap water from faucet. Add appropriate amount of water to each plant.
9) Repeat steps 6 and 7 (plant exposure steps) five times a week until Thanksgiving. The class participation occurs here.
The first thing that we tested was plant height. We hypothesized that all of our test plants should have a short plant height, and we expected them to die rather quickly. However, we got mixed results as we measured plant height. At the end of our two week test period, the tallest and the shortest plants were both control plants. Our third control plant was right in the middle of our plant height range. (see Plant Height Graph) This means that we saw no correlation between exposure to tobacco smoke and plant height.
We did however see a result in our leaf observations. We used a numeric system for measuring the size of leaves. We assigned a one to sprouting leaves, a two to small leaves, a three to medium sized leaves, and so on. We then added all these numbers from each plant to get the “leave count” which is actually a measure of both the leave size and the amount of leaves.
Our results for this test were clear. The control group of plants had a consistently higher number of leaves than the test plants. (see Number of Leaves graph) There is an odd fluctuation in the middle of the graph, but this is due to natural plant variation in growth. The difference between test and control plants is most evident at the end of the graph. As time goes on you see a clearer separation between the two groups. This pattern is further illustrated when we look at the total change in leave measurements from the beginning of the test period to the end. (see Change in Leaf Count graph) With the exception of one test plant that held it’s leaves until the last few days of testing, the control plants had a much higher positive change in leaf count while the test group lost most of it’s leaves about midway through the experiment. We also noted as qualitative data that the two test plants did sprout new leaves after we began exposing them to smoke. However, when leaves did appear they were mutated. The mutation can best be described as two leaves joined together with two separate points.
One reason that the tobacco smoke had no effect on the test plants height is that they grew straight up while the control group plants were a little twisted and sideways. This is due to the weight of the leaves on the plant stems. The test plants had no leaves to weigh them down, so they grew straight. The weight of the huge leaves on our control group caused the plants to lean from side to side causing often times, a shorter plant height. We further hypothesize that although the test plants did grow as tall as the control plants, they would eventually have died due to their lack of healthy leaves.
The impact that smoking had on the plant leaves was due to the chemicals in the cigarettes getting into the pores of the plants, causing them to suffocate. They were probably absorbing toxins rather than sunlight and carbon dioxide. Without sunlight and carbon dioxide the toxins weighed the leaves down. They were very droopy after each time that we tested them.
We had no test to see if this was how the toxins effected the plants, but the leaves also became very dry, brown, and brittle as the experiment progressed. This lead us to assume that the smoke caused the plants to be dehydrated in some way. The toxins could have been absorbed in the test plants’ soil. This could bring toxins into the plant rather than water which would explain why the plants were dehydrated.
The decreased amount of light that reached the test plants also could have caused them to loose their leaves. The test plants had no way of getting sunlight for the half hour time period while they were being tested each day. This is a small amount of time for a plant to go without sunlight, and this factor should have minimal effect on the plants growth if any. However, decreased amount of light for half an hour everyday over a period of time such as two weeks could have inhibited the plants leave development. This could have contributed to the effect of the toxins in the cigarettes on our test plants.
Our experiment yielded conclusive results that smoking does have a detrimental effect on plants. the Smoky Situation was not foolproof, however. In our procedure, we lit all six cigarettes initially, and they would burn together. This was not always the case. Sometimes because of lungpower, or even wind, we would set the timer and realize later that one, two or even four cigarettes were not lit. In order to save as much time opening the lid, we would relight the cigarettes when the filters were extinguished. Opening the lid was a hazard to the entire experiment. It was a necessary step, burning the filters would release all sorts of chemicals that would change all the cigarette toxin variables. When we lifted the lid, smoke would escape; each tester had a different speed in doing this. The faster the filters could be dropped into the can, the less smoke would be released and more would be able to circulate for the reminder of the time. regardless, since all the plants were smoked together in the aquarium, they each received the same amount of smoke. It is only in calculating the amount that there are uncertainties.
In calculating data, there are some unexplainable dips in the graph regarding leaf count. this can be best explained by the fact that there were no strict guidelines in determining whether a leaf was small, medium, or large. In fact, the leaves didn’t change so much in size as they did in appearance, The smoked leaves stayed a reasonable size, but turned a wrinkled brown until they shriveled and fell off. That is the explanation of the sudden drop in leaf count for the test plants. It was entirely left up to the judgment of each individual tester. In making a spreadsheet, we converted the written observation into numerical statistics. A sprout equaled one point, a small leaf two, a medium leaf 3 etc. The testers were also at liberty for their measurements. Even though we explained clearly in the teaching packet presentation, some testers later reported that they didn’t measure exactly form the base to the top of the stem. The variations in height didn’t prove to be as significant, since both the test and control groups were relatively similar.
From the beginning of the experiment we had many problems planting our bean plants. We planted about forty plants, and of that forty, two sprouted. The Wonderwheel group donated eight plants, since we seemed to be the only group having trouble. Because of the demands of the Wonderwheel’s experiment they had to take back two of their plants they had donated, allowing only three control plants for our experiment. That explains the difference in the number of control plants versus the number of test plants. Another issue we dealt with was that the six plants the Wonderwheel group donated were divided into three pots, with two plants in each pot, this could have had an effect on the plants growth because the plants shared such a small space. There was also some confusion about when to measure the control plants. We did not measure the controls plants every time we measured the test plants, so therefore we had a difficult time analyzing our data. Another flaw in the experiment was the inconsistency of watering the plants. We didn’t have a set time schedule for watering the plants, so therefore that variable was not controlled. If we did this experiment again we would arrange a method or strategy for watering the plants, such as watering them every time after we tested them.
Test Plants Height Leaf Count Other Results/Observations
1. “Booth Number 144”. Hill, Jeni < http://tqd.advanced.org/3692/past/42nd/htmls/144.html
2. “Re: How Does Cigarette Smoke Effect Plants”. Galloway, Cynthia < http://madsci.wustl.edu/posts/archives/mar98/889055849.Bt.r.html
3. “NASA study shows common plants help reduce indoor air pollution......”. Tropical Plants Zone 10.
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