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Answers Prelab assign 2 & 3(2)

Answers Prelab assign 2 & 3(2) - ANSWERS FOR PRE-LAB...

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ANSWERS FOR PRE-LAB ASSIGNMENT FOR LAB EXERCISES #2 and #3 PRE-LAB ASSIGNMENT: Read the background information and complete all of the activities. This entire assignment is due at the beginning of Lab #2: Microbes: Good or Bad . OBJECTIVES: By the end of this pre-lab assignment, students will be able to… Convert between nm, μm, and mm and L, ml, and μl. Describe the size differences among microorganisms and other cells. Compare and contrast prokaryotes, eukaryotes, and viruses. Describe the extent to which prokaryotes dominate life on earth in terms of number of organisms. Describe the birth of the compound light microscope and how it changed our understanding of life on earth. Make serial dilutions and understand the math necessary to do so. You will need a cm ruler to complete this assignment. Metric rulers can be obtained at the Bookstore. BACKGROUND INFORMATION: What are microbes? Last week, you had a chance to make observations about a microbe called Erwinia carotovora. You saw how this infectious agent caused a disease in potatoes known as “soft rot.” You determined it was the causal agent using Koch’s Postulates. But, were you certain at the time whether this causal agent was a bacteria, fungus, virus, of protozoa. It wasn’t until the invention of the microscope around 1590 that scientists were even able to see the world of microbes. But, once they were, then there was a need to understand more about the similarities and differences among these microorganisms. Question: Using information from last week’s lab, compare the dates of the invention of the microscope and the work of Koch. What other progress was made in the world of science between these two dates? What were scientists doing? (Sadava, 5) 1590, two Dutch eye glass makers, Zaccharias Janssen and son Hans Janssen experimented with multiple lenses placed in a tube. The Janssens observed that objects viewed in front of the tube appeared greatly enlarged, creating both the forerunner of the compound microscope and the telescope . 1665 – English physicist, Robert Hooke looked at a sliver of cork through a microscope lens and noticed some "pores" or "cells" in it. 1674 – Anton van Leeuwenhoek built a simple microscope with only one lens to examine blood, yeast, insects and many other tiny objects. 1876- A founder of the science of bacteriology , Koch devised a procedure to demonstrate that the bacterium Bacillus anthracis causes anthrax , a disease of animals that can also be transmitted to humans. It was the first time that a particular bacterium was shown to be the cause of a particular disease. It appears that there was little progress between the 1600s and the late 1800s. You might have learned that cells and/ or microbes (remember, most microbes are cells) can be prokaryotic or eukaryotic cells. The three domains include Bacteria, Archaea , and Eukarya.
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