Investigating Microorganisms In Pond Water

Name: ______Period: ____ Date: ______Lab: Investigating Microorganisms in an Aquatic Environment (Protist Lab) Aquatic environments support a high level of biodiversity, or diversity of organisms. Many of these organisms are microscopic. These microorganisms are essential to the balance of the aquatic ecosystem. You may already be familiar with some of these organisms, like the algae, amoeba, paramecium, and euglena. Purpose In this lab, you will become familiar with common microorganisms and gain experience exploring the microbial world. Materials Aquatic samples, compound light microscope, slides, cover slips. Procedure 1) Review the parts of the compound light microscope. Match the structures in the picture below with their parts on the side and define each structure. If necessary, refer to Appendix D in the textbook. _____ Stage clips:

_____ Fine adjustment knob:

_____ Eyepiece:

_____ Base:

_____ Objective:

_____ Nosepiece:

_____ Stage:

_____ Arm:

_____ Illuminator:

_____ Course adjustment knob:

_____ Diaphragm:

2) Remember, the proper way to carry the microscope by placing one hand beneath the base and grasping the arm of the microscope with the other hand. The microscope needs to be held against your midsection. 3) Obtain a microscope from the cabinet. At the end of the lab it must be returned to the correct storage location with the electric cord wrapped around the microscope.

What is the number of the microscope you are using? ______4) Obtain a glass slide and glass cover slip. Be careful, but if you break either see your teacher for proper disposal. Do NOT throw broken glass in the regular trash. 5) You have been provided with a diagram of common aquatic microorganisms that you should look over and reference. 6) Using a dropper pipette at the class station, place a drop of pond water on your slide. Prepare a wet mount of a pond water sample as described below. Write the sample source in Data Table 1 AND your drawings.

Preparing a Wet-Mount Slide a. Obtain a clean microscope slide and a cover slip. A cover slip is very thin, permitting the objective lens to be lowered very close to the specimen so do NOT lose it! b. Place a drop of the sample water on the center of a clean dry slide.

c. While holding the cover slip upright, carefully place one edge of the cover slip next to the water. Slowly lower the upper edge of the cover slip onto the water. The goal is to minimize or eliminate air bubbles under the cover slip.

d. A piece of paper towel can be placed at the edge of the cover slip to draw out some of the water, further flattening the wet mount slide. 3) Use your microscope to view your aquatic sample. Remember to begin with the lowest power (shortest- 4x- RED) objective lens and the coarse adjustment knob. Then use the fine adjustment to focus at this power before moving the medium objective lens. Search and find as many microorganisms as possible. List all organisms in Data Table 1. Draw at least one organism from each sample. For each microorganism you draw, give the following information: a. Name of organism (use reference guide) and sample source b. Sketch a drawing of what you see through the microscope (Write the total magnification, including both the ocular and objective magnification; if you cannot remember how to calculate total magnification, refer to Appendix D in the textbook) c. Description of physical appearance and movement 4) Wash and dry your slide and cover slip between samples. Return the slides and cover slips DRY at the end of the lab. Ask for a clean up stamp! Data Table 1 # of Different Sample Source Organisms Types of Organisms Identified Post Lab Questions: Reference Chapter 20 in your textbook. 1. What is biodiversity?

2. Which source of water had the most biodiversity? How many different types of organisms were present in this sample?

3. Which source of water had the least biodiversity? How many different types of organisms were present in this sample?

4. How is total magnification calculated?

5. Why was it necessary to begin your observation using the low power objective first?

6. Were most of the organisms you observed unicellular or multicellular?

7. Do all the organisms you see swim in the same way? Describe at least 3 different ways that protozoans move.

8. Were any of the same types of organisms present in different samples? Which organisms are found in several samples?

9. List two ways to distinguish between living and non-living matter.

10. To which kingdom do most of the unicellular organisms you saw belong? Water Source: ______Water Source: ______Identify Organisms: ______Identify Organisms: ______Movement Description: ______Movement Description: ______

Ocular lens magnification: ______Ocular lens magnification: ______Objective lens magnification: ______Objective lens magnification: ______Total magnification: ______Total magnification: ______

Water Source: ______Water Source: ______Identify Organisms: ______Identify Organisms: ______Movement Description: ______Movement Description: ______

Ocular lens magnification: ______Ocular lens magnification: ______Objective lens magnification: ______Objective lens magnification: ______Total magnification: ______Total magnification: ______