User:Bickey Chang/Notebook/Biology 210 at AU
Jul 2, 2014
Lab 2: Protists
Introduction
Living organisms on earth can be divided into prockaryotes, eukaryotes, and archaea. Algae and prostists represent two large groups of unicellular eukaryotes. Algae can perform photosynthesis while protists are consumers which obtain nutrients from other organisms. (Bentley et. al, 2014)
In this lab, we aim observe a Hay Infusion Culture of microorganisms from Transect 1 and identify and characterize four microscopic organisms using a dichotomous key. We hypothesize that different organisms can be found in different layers of the Hay Infusion. More specifically, we hypothesize that photosynthesizing microorganisms will be found in the top layer of the Hay Infusion Culture, while non-photosynethesizing microorganisms will be found in the bottom layer.
Materials and Methods
We prepared a Hay Infusion Culture in the last lab (see Lab 1 entry for information on the preparation of the culture). The Hay Infusion Culture was observed. Wet mount slides were prepared with liquid from the top layer of the Hay Infusion Culture and the bottom layer of the Hay Infusion Culture and were observed under the microscope. Four microscopic organisms were identified and characterized using Ward's dichotomous key. (Ward, 2014)
A sample of 100 uls was taken from the shaken Hay Infusion Culture and serially diluted for plating on agar petri dishes with and without tetracycline. 100 uls of Hay Infusion sample was added to 10 mls of sterile broth. 100 uls was transferred to the next 10 mls of sterile broth. This transferring procedure was repeated two more times. With each serial dilution, the Hay Infusion Culture mixture was diluted by 10^2 times. Figure 1 shows the serial dilution process.
Figure 1 Serial Dilution of Hay Infusion Culture
Figure 1 shows the serial dilution procedure of Hay Infusion Culture.
After the serial dilution, the culture and broth mixes were plated onto four agar petri dishes without tetracycline and four agar petri dishes with tetracycline. The petri dishes were left at room temperature to grow for four days.
Results
Figure 2 shows our Hay Infusion Culture.
Figure 2 Transect 1 Hay Infusion Culture
Figure 2 is a photograph of the Hay Infusion Culture from Transect 1.
The Hay Infusion Culture was tan-colored and clouded, with colony-like components floating on top. There was also brown sediment at the bottom. The smell was biotic and unpleasant.
Figure 3 shows four microorganisms which were observed from the Hay Infusion Culture under the microscope at 10x magnification.
Figure 3 Microorganisms in Transect 1 Hay Infusion Culture
Figure 3 shows microorganisms which were observed from the Hay Infusion at 10x magnification.
Two types of algae, gonium and pandorina, were observed from the top layer of the Hay Infusion Culture. Gonium was green and non-motile, with a colony size ranging from 2-10 (20-100 um) under the ocular micrometer. Pandorina was also green and non-motile, with a spherical shape and a size of 10 um.
Two types of protists, arcella and stentor, were observed from the bottom layer of the Hay Infusion Culture. Arcella was colorless and motile, with a size of 20 um. Stentor was brownish with green spots inside, with a size of 250 um.
Discussion
We hypothesized that microorganisms found from the top of the Hay Infusion Culture would be photosynthesizing while microorganisms found at the bottom would not. In this lab, we observed two green algae in the top layer. Their green color from chlorophyll pigments support they are photosynthesizing microorganisms. We observed arcella and stentor from the bottom layer. Arcella is colorless and motile, so it does not have pigments to conduct photosynthesis. Stentor is brownish in color, but notably has green spots, which may have photosynthetic abilities. Further research shows that the green spots observed are actually algae which is in a symbiotic relationship with stentor. (Webb, 2014) In general, our observations supported our hypothesis that photosynthesizing organisms lived near the top layer and non-photosynthesizing organisms lived near the bottom layer.
Organisms must be able to sustain fundamental needs of life. (Freeman, 2014) Gonium presents such an example. It performs photosynthesis, allowing it to acquire energy. Its structure is simple, but it is composed of single cells. It is a eukaryote and contains genetic information for life (not directly observed in this lab). There is also diversity in the species, which provides the opportunity for continual evolution.
If the Hay Infusion Culture had been observed for another two months, we would expect the culture to contain more diversity of organisms. However, the carrying capacity could also be reached by two months, causing some organisms to be unable to survive and reproduce. We would expect photosynthesizing organisms to continue to proliferate, as they are not dependent on others for their food source. Well-adapted protists who are able to secure their food source in competition would also continue to proliferate.
References
1. Bentley, Walters-Conte, & Zeller. 2014. Biology 210 Laboratory: The Diversity of Life Lab Manual. Washington: American University.
2. Ward's Natural Science. 2014. Free-Living Protozoa. Rochester, NY: Ward's Natural Science.
3. Freeman, Scott. 2014. Biological Science. Prentice Hall: Boston.
4. Webb, Howard. 2007. Stentors. Micscape Magazine. Accessed Jul 7 2014 from http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul07/hw-stentor.html
Jun 30, 2014
Lab 1: Biological life at AU
Introduction
Life on earth is varied, with more than a million different forms of life currently characterized by scientists. (Bentley et. al, 2014) In this lab, we aim to study a 20 by 20 transect of land on campus at American University. The mini ecosystem is named the mini-marsh (also Transect 1). We hypothesize that the transect will contain multiple forms of life as well as abiotic components.
Materials and Methods
Two lab partners surveyed a transect of land and conducted a comprehensive qualitative analysis of life forms and abiotic components in Transect 1. Transect characteristics including location and topography were also noted.
A 50 ml sample of soil and ground vegetation was brought back to the laboratory to prepare a Hay Infusion Culture. 11.6 g of soil was placed placed in a plastic jar with 500 mls of Deerpark water and 0.1 gm of dried milk. The mixture was mixed and placed in a corner of the lab with an open lid for two days.
Results
Transect 1 is located in front of the Kogod School of Business in the Massachusetts entrance of American University. The topography is slightly raised. Both biotic and abiotic components were observed on the mini-marsh transect, and a variety of plant life was observed Figure 1 shows an aerial view of the transect.
Figure 1 Aeriel View of Transect 1
Figure 1 shows the aerial view of Transect 1.
Figure 2 Photograph of Left Side of Transect 1
Figure 2 is a photograph of Transect 1 from the left side.
Figure 3 Photograph of Right Side of Transect 1
Figure 3 is a photograph of Transect 1 from the right side.
Plant life on Transect 1 included numerous types of bushes (bushes with white flowers, bushes with berries, a third type of bushes) and grass-like plants (grass, tall grass, weeds, cattails). All plants were flourishing. Abiotic components include a drainage, small rocks, large boulders with different minerals, and a lamp post.
Discussion
We hypothesized that the transect will contain multiple forms of life as well as abiotic components, and our findings were consistent with this hypothesis. In our qualitative analysis, we found a variety of different plants were present on Transect 1. All plants were flourishing, leading us to believe the ecosystem is stable. We also found some abiotic components in the Transect 1. This is probably due to the fact that the transect is located on a university campus built by man.
Further study of additional life forms present in the transect can help increase our understanding of this ecosystem. One limitation of this lab was we used qualitative observations to analyze the transect. Use of microscopes and other bioessay methods could help us better understand and characterize smaller life forms which are also integral to this ecosystem.
Reference
1. Bentley, Walters-Conte, & Zeller. 2014. Biology 210 Laboratory: The Diversity of Life Lab Manual. Washington: American University.
