User:Shraddha Batra/Notebook/Biology 210 at AU

January 31, 2014 Lab 1: Understanding Cell Specialization in Green Algae and Defining Niches

I. Introduction The title of this lab is "Understanding Cell Specialization in Green Algae and Defining Niches."There were two main objectives that were addressed in this dual-part experiment. In the first portion of this lab, the purpose was to provide an understanding of how organisms progress and develop over time. More specifically, three organisms of the Volvocine line were studied and their cells were analyzed to examine changes in complexity and specialization. The purpose of the second portion of this lab was to demonstrate the many components that constitute an ecosystem. There are various biotic and abiotic components in an ecosystem, and these elements were examined in a 20 by 20 foot transect (#4) of American University's garden. The following are the two hypotheses for the two experiments:

Hypothesis 1: The Volvocine line will show a progression of cell complexity among the three organisms studied.

Hypothesis 2: A study of AU's garden will reveal that there are a number of living and nonliving components of an ecosystem.

II. Methods and Materials Procedure 1: Understanding Cell Specialization in Green Algae 1. A drop of Chlamydomonas was placed onto a microscopic slide. 2. A drop of protoslo and a cover slip were added to the slide. 3. Organism cells were examined using a microscope under 4X, 10X, and 40X magnifications. 4. Cell number, colony size, and cell descriptions were noted. 5. Steps 1-4 were repeated for Gonium and Volvox.

Procedure 2: Defining Niches' 1. Students arrived at the 20 by 20 foot transect (#4) of American University's garden. 2. Transect descriptions, biotic components, and abiotic components were identified and noted. 3. A sample of the transect was taken in a 50 mL tube. 50% of the sample was soil and the remaining 50% were materials found above soil such as leaves and plants.

III. Observations and Data Procedure 1 Data: Procedure 2 Data: -Description: The location of the American University garden was in a secluded area behind the campus, away from the academic buildings. The 20 by 20 foot transect was surrounded by 6 rectangular plots in which plants were growing. The land was moist due to recent rainfall, and most of the grass and plants were shriveled and dry due to the cold weather/season. Biotic and abiotic components included: leaves, tree branches, dry grass, dead flowers, little worms, soil, rocks, and wood chips.

IV. Conclusions and Future Plans As evident in the image of data for Procedure 1, the cells in the Volvocine line differed from one another. Beginning with Chlamydomonas, it is very easy to identify each individual cell. In is distinguishable from Gonium, which contains a colony of many cells clumped together, making it more complex than the individual Chlamydomonas cells. Continuing with this progression of complexity, Volvox appears as colonies that resemble large balls and consist of thousands of cells. Thus, over time in the Volvoine line we observe organisms undergoing greater cell complexity. Oftentimes, increasing complexity can produce benefits for organisms such as in the form of cell specialization. The observations in this portion of the lab are in agreement with the stated hypothesis. Other future studies could also examine the various factors contributing to increasing cell complexity.

In Procedure 2, we learned that an ecosystem consists of both biotic (living) and abiotic (nonliving) components. As a result, an environment and its elements influence how species exist. In the studied transect, there were few visible biotic elements due to the effects of cold climate. This may contribute to fewer organisms being found in the plant material sample about the soil, depending on the nature of the organisms. If this experiment were to be repeated again, the organisms within the soil should be further examined during daytime rather than nighttime. Data was taken at night; therefore, some elements may not have been identified due to low visibility. Overall, the observations support the stated hypothesis.