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. 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 a dichotomous key.

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

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

Discussion

References

1. Bentley, Walters-Conte, & Zeller. (2014). Biology 210 Laboratory: The Diversity of Life Lab Manual. Washington: American University.

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

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.