ACCELERATED BIOLOGY                                                                          ROOM COPY

                   WORKSHEET 5-1 : INTRO TO MICROBIOLOGY

1. Today scientists recognize 5 large kingdoms of living organisms. They believe that through        evolution one original kingdom probably gave rise to all the other kingdoms. A family tree is
       a common tool they use to show which kingdoms might have evolved from which.
     A: Microorganisms can be found in which 3 of the 5 kingdoms?
     B: Which group of microorganisms are thought to have given rise to plants? Explain.
     C: What criteria is used to place Kingdom Monera on one branch of the family tree while             Kingdoms Protista and Fungi are placed together on a separate branch of the family tree?

2.  A: Place the following organisms in order from the largest microorganism to the smallest.
       Yeast      |      E. coli      |      Amoeba      |      Paramecium      |      Chlamydomonas
     B: What unit is used to measure microorganisms?

3. Classify the following microorganisms as prokaryote or eukaryote.
     A: algae                        B: bacteria                  C: protozoa                      D: fungi

4. All organisms need energy, but obtain it using different techniques. The two main techniques
       are autotrophs, which make their own food using chlorophyll, and heterotrophs, which catch        and eat other living things. Three organisms are described below. Determine which is an        autotroph, which is a heterotroph, and which is both.
     A: clear body color // is covered with cilia for movement
     B: green body color // has flagella for movement
     C: green body color // does not move (just floats in water)

5. Most microorganisms have specific needs for growth. In other words many microorganisms        grow best when they are grown under certain conditions for temperature, osmotic pressure,        and pH. Three choices for each of the following environmental conditions will be provided.        List which of the 3 choices will provide the best growing conditions for most microorganisms.
     A: Temperature -> 0o - 20oC | 20o - 40o C | 40o - 90oC
     B: Osmotic Pressure -> Isotonic | Hypertonic | Hypotonic
     C: pH -> below 5 | 5 - 9 | above 9

6. To humans it is only natural to assume that all living things need oxygen, but surprisingly not all        organisms need oxygen to live. From the description of its habitat, determine if the following        three organisms are aerobic, facultative anaerobic, or obligate anaerobic.
     A: can live for months inside a sealed can of food
     B: can live on the surface of land or water
     C: can live in the intestine of larger animals such as humans

7. A growth curve shows how a population of microorganisms will change over time when placed        into a new, but limited food source. Typically a growth curve will show 4 phases in the life        cycle of the population of microorganisms.
     A: List the 4 phases that a typical growth curve displays.
     B: Determine which of the following conditions will most likely produce a typical growth curve.
            1: some bacteria entering a carton of milk left on the counter for several days
            2: some algae growing in a lake with several rivers constantly bringing in fresh nutrients
            3: some fungi growth on a single slice of bread

8. There are numerous techniques available for killing unwanted microorganisms. These techniques        can be organized into 3 main categories called chemical, antibiotic, and physical tools.
       Indicate whether each of the following situations would best be solved using chemical,        antibiotic or physical tools for killing the unwanted microorganisms.
     A: sterilizing the skin after a bad cut
     B: sterilizing a operating table in a hospital before an operation
     C: sterilizing milk before placing it into a carton
     D: fighting a lung infection
          (EXTRA) E: sterilizing raw hamburger before packaging by a butcher

9. Microorganisms are used for a wide variety of tasks. Each of the following statements pertains
       to one common use for microorganisms today.
     A: Some microorganisms are used to produce …………………. & ……………… by             breaking down organic compounds.
     B: Sauerkraut and pickles can be produced by the process of ………………………… .
     C: Coliform can be used to indicate water that is …………………, while Protozoans indicate             water that is …………………. .
     D: Some microorganisms can cause milk to spoil leading to the production of ……………..
            & ……………….. .

10. Most microorganisms can be grown on two main types of media; broth which is a liquid, and        agar which is a solid.
     A: Which type of media should I use if all I want to do is keep a culture growing by
             subculturing it?
     B: Which type of media should I use if I want to view some of the bacteria I am trying to grow?

11. I can transfer microorganisms from one place to another using either a wire loop or a pipette.
     A: Which tool would be better for transferring just enough microorganisms to produce individual              colonies on an agar plate?
     B: Which tool would be better for transferring enough microorganisms to cover the entire             surface of an agar plate?

12. I need to sterilize three different materials. Which method of sterilizing would work best for        each of these three materials?
     A: bacteria on an agar plate                        B: a wire loop                        C: a jar of broth

13. I have two bacteria growing in a culture in a test tube. I need to separate them so I can have        only one bacteria growing on its own (either on a plate or in a tube). How could I use the        streaking technique and an agar plate to separate the original two bacteria?

14. Microorganisms are often stained to make them easier to view or identify. Simple staining
       and gram staining are two of the most common methods of staining bacteria.
     A: State one way in which these two staining methods are alike.
     B: State one way in which these two staining methods are different.

CRITICAL THINKING QUESTIONS:

15. Under ideal conditions, E. coli bacteria, common in the human digestive tract, reproduce
        every 20 minutes. Assuming that all offspring survive and reproduce also, how many
        bacteria could result over an 8 hour time period from one original E. coli?

16. Clostridium tetani, the bacteria that cause tetanus, are obligate anaerobes. From this would
        you infer that a deep puncture wound or a surface cut would be more likely to become         infected by tetanus bacteria? Explain.

17. Fleming discovered penicillin, a bacteria-killing drug, while studying a mold that had grown on        his agar with his bacteria cultures. Why would a mold produce a drug that kills bacteria?

18. We use microorganisms to make a variety of foods such as cheese, pickles, and wine. Why,        then, can we safely eat or drink these foods?

19. All normal healthy people have microorganisms in their intestines and on their skin.
     A: Why don't these microorganisms harm us?
     B: Describe a condition in which they might harm us.

20. Microorganisms like many higher life forms can be found living freely in the air, water, and
       soil, but can also be parasitic inside another living thing. Generally speaking, would a        microorganism need to be more complex if it was free-living or if it was parasitic? Explain.

21. Look up the terms tissue and organ.
     A: Can a microorganism contain any tissue?
     B: Can it contain any organs?
     C: Give one explanation for both answers above.

22. Many disease-causing microorganisms will invade the human body, but few kill you. Why
       might it be a benefit to the microorganism not to kill you?