Experiment - how the submerging of the Elodea Canadensis leaves in various liquids with different pH levels affect the stream of chloroplasts inside the Elodea Canadensis cells.
Cytoplasm streaming within Elodea Canadensis (the pond weed)
The movement of cytoplasm inside a living cell is called cytoplasm streaming. Cytoplasm streaming can be observed in both animal and plant cells. The function of the cytoplasm streaming (which is also called cyclosis) is transporting enzymes, nutrients, particles with larger sizes within cells, enhancing the exchanging between cells as well as between organelles of a cell. It is known that its movement can be increased by the light from the outter environment and that it is dependent on pH level and on temperature.
In this experiment we wanted to find out: how different environments affect the cells of the pond weed – in other words, how the submerging of the Elodea Canadensis leaves in various liquids with different pH levels affect the stream of chloroplasts inside the Elodea Canadensis cells.
If the pond weed (Elodea Canadensis) is submerged in a higher pH level liquid, the speed of the cytoplasm stream (the speed of chloroplast movement) will increase (the higher pH of the liquid, the higher the speed of chloroplast movement), because when it is exposed to water (pH level 7), cytoplasm streaming is either very slow and cannot be visible or it does not take place at all – it is a comfortable environment for it. Therefore, the more the pH level of a liquid differs from the pH of 7 (water), the higher is the the intensity of the cytoplasm stream, as the environment becomes less pleasant for the cells of the pond weed.
The variables of this experiment are following:
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Laboratory setup (materials and equipment) :
Liquids – “Johnson’s Baby” shampoo (pH 4); “Coca Cola” lemonade (pH 5); “Ajax” toilet cleaner (pH 6). Pond weed leaves, water, pH meter, light microscope, ocular ruler (±1.25 nm), chronometer (±0.001 s), coverslip, slide.
Method of work:
1) We measured the pH levels of the liquids used in the experiment with a pH meter.
2) We placed the leaf of the pond weed on the slide, put on a drop of water on it and afterwards placed the coverslip on top of it.
3) Afterwards we made the process of submerging the pond weed leaf in the first liquid, which was the “Johnson’s Baby” shampoo (pH 4), by placing a paper towel on side of the coverslip and then putting a few drops of the solution on the other side – the paper towel absorbed liquid and that way it made the solution to flow under the coverslip.
4) After that we put the pond weed under the microscope’s looking glass to get the view of 400x magnification.
5) Then we measured the traveled distance of a separate chloroplast in a particular period of time (which was 10 seconds) by using an ocular ruler and a chronometer.
6) We repeated this same algorythm 5 times to get more measurements.
7) When this was done, this same process was repeated from the beginning twice with a new leaves, which were submerged in a different liquids (2nd attempt was with the “Coca Cola” (pH 5) bath foam and the 3rd attempt was made with the “Ajax” toilet cleaner (pH 6)).
(Dara #1) Data collected by measuring the distance traveled by a single chloroplast in a period of 10 seconds in the leaves of Elodea Canadensis.
(Data #2) Data of the calculated speed of a separate chloroplast.
Johnson’s Baby Shampoo
0.01 s + 0.00125 nm=0.01125
0.01 s + 0.00125 nm=0.01125
0.01 s + 0.00125 nm=0.01125
Judging by the results, it can be seen that the pH level of the environment, in which the cell is located in, indeed is the main factor that influences the movement of the chloroplast in the cell or the cytoplasm streaming in general. This is confirmed, but my hypothesis was proven wrong during this experiment – as the pH differs more slightly from the pH of 7 (water pH), the speed of the movement of the examined chloroplast is decreasing. (Johnson’s Baby (pH 4) ; Coca Cola (pH 5) ; Ajax (pH 6) ) The are several reasons, why the hypothesis proved wrong. First of all, it could be a result of unprecise measurements. Secondly, it could be the fault of mistaking a random chloroplast to the chloroplast, for which I measured the traveled distance - there were many other chloroplasts, which made contact with that exact chloroplast, which could’ve also slowed it down. Also the environment created in the class could have affected the cytoplasm streaming – temperature of the room, to be more precise. These could be the sources of the relative errors, which could be smaller. (Johnson’s B. (pH 4) 0.01574 nm/s; Coca Cola (pH 5) 0.1321 nm/s; Ajax (pH 6) 0.01247 nm/s)
1) The chloroplasts chosen to be examined to measure their traveled distance should be chosen from spots, where there are least chloroplasts, so they could flow freely with no barriers of other chloroplasts to stop them. Also a help from another person would bring some more positive results, so both could concentrate on their own parts of measuring – one of them supervises the time, while the other one is paying full attention to the movement of the chosen chloroplast.
2) The temperature of the environment and microscope could be controlled more, because temperature may also be a great factor affecting the cytoplasm stream. Constant temperature should be maintained for the experiment to maintain precision. If any of the temperatures slightly change, all the necessary things to maintain the begining temperature should be done (for example, let the microscope drop the temperature after a period of working time).