User:Ambuj Suri/Notebook/Biology 210 at AU

Lab 2

The purpose of this lab is to identify the different organisms present in the hay infusion developed from the transect sample from last week. The organisms come from three different niches in the infusion (bottom, middle, top) and were identified using a dichotomous key.

The two organisms identified from the top of the hay infusion include chlamydomonas and euplotes sp. Busaria Truncatella and paramecium aurelia were found in the middle. Finally, paramecium bursaria and vorticella were found at the bottom of the hay infusion. The organisms differ close versus away from plant matter because those that are far away from plants most likely do not rely on them for food.

All of the species are motile (and were therefore hard to locate under the microscope). Paramecium aurelia, paramecium bursaria, bursaria truncatella and euplotes sp are ciliates that rely on cilia for motility whereas vorticella and chlamydomonas have flagellas. Of the six identified, chlamydomonas is the only photosynthetic organism whereas the remaining five rely on external sources of food. Finally, chlamydomonas is the only algae whereas the remaining five are protozoa.

Chlamydomonas are photosynthetic, unicellular organisms that replicate via both sexual and asexual reproduction. Therefore, this organism fits the five necessities of life (energy, cells, replication, information, and evolution). Firstly, they acquire and use energy in the form of sunlight, which is converted to energy through photosynthesis. They are unicellular, and therefore contain at least one membrane bound cell (which comprises the whole organism). They replicate in the form of cell division, and sometimes transfer information creating new daughter cells. As seen in the volvocine line from which chlamydomonas originate, these organisms have also evolved into more complex organisms, such as the volvox.

If the hay infusion “grew” for another two months, then the carrying capacity would steadily decrease. The organisms would reproduce and simultaneously compete for food and space. The competition for food would result in fierce competition as populations grew and food sources dwindled. Therefore, the number of organisms that would be able to survive in each niche would decrease, and only the fit organisms would remain. In this way, the selective pressure of food availability would lead to population change from generation to generation.

A serial dilution was prepared and plated onto agar plates with and without tetracycline to assess antibacterial resistance of the bacteria in the hay infusion. In order to create the serial dilution, 100 microliter sample from the hay infusion was diluted with sterile broth. The figure below illustrates the dilution process.

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Lab 1

The purpose of this lab is to examine biodiversity of an assigned transect at American University.

The transect is located in the northwest corner of American University between Butler Pavilion and Hughes hall and is marked by four popsicle sticks labeled with numbers 1-4. It is approximately 20 by 20 feet containing sidewalk on both sides of a patch of grassy land, containing trees, plants, and lamp posts.

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The five abiotic features observed in the transect include a two metal lamp posts, littered ribbon, sidewalk, pebbles, and a cigarette bud. The five biotic features observed include a small black squirrel, a human between the ages of 18 and 22, seven large trees, several small ferns, and weeds. Their specific location is indicated on the aerial map below.

After observing the abiotic and biotic features above, a 50 mL sample of soil and leaves was taken from the transect to create a hay infusion. The hay infusion will be used to examine the different species of bacteria, archaea and eukarya that live in the transect.

http://i1382.photobucket.com/albums/ah252/ambujs/photo_zpsd7c873fd.jpg