“Exercise 1: A Bean Water Micro-communityNote: Bean water incubation requires at least 3 days. Plan accordingly.You will need: Table shown below to record observations, six beans, 50 mL beaker, and tap water. Afterincubation, a clean slide, eye dropper from dissection kit, drop of bean water, toothpick, heat source,crystal violet stain, staining tray, glass of water, work area protected from staining and microscope.PROCEDURE:1. Set up the following table to record observations for Exercise 1 and Exercise 2.Organisms in Micro communitiesOrganismBeanwaterPondwaterMotile or sessile(reason)Producer or consumer(reason)2. Place six beans from the experiment bag in the 50-mL beaker and half-fill it with tapwater. Allow the beaker to stand in a warm place for 3 to 4 days. Good locationsinclude the kitchen near the stove and a utility room near a hot water heater.3. Prepare and stain a slide of the bean water. To do this, after the beans have been inthe water for several days, dip the clean eyedropper into the bean water and place asmall drop of bean water on a blank microscope slide. Spread the drop with thetoothpick until it is about 2 mm in diameter.4. Light a candle or ignite a long kitchen match or lighterto dry the bean-water slide. Use the test tube clamp tohold the slide by one end in a horizontal position withthe spot of bean water on top. Gently pass the slidethrough the flame several times. This process is calledâfixingâ the specimen and sticks the cells in the bean water to the slide. Do not heatthe slide after the water has evaporated or pass it through the flame so slowly thatsoot can accumulate on the bottom of the slide. But if the latter happens, you canclean the bottom of the slide with a damp tissue.5. Continue to hold the hot slide with the test tube clamp. Have aglass with clean water by the sink or basin where youâreworking. Also have a clock or watch with a second handnearby. Hold the slide over the staining tray with the test tubeclamp. Place a few drops of crystal violet stain on the driedbean residue on the slide. Be careful not to spill the crystalviolet outside the staining tray as it is a very strong stain. Staining the slide will makethe microorganisms from the bean water have more contrast and easier to see.LabPaq: BK-101 Page 696. After one minute, rinse the excess stain off of the slide by dipping it into the glass ofwater. Gently shake excess water from the slide into a staining tray, and allow theslide to air-dry.7. View the dry slide directly with your microscope; no slide cover is required. Drawwhat you see. Use the chart of microorganisms at the end of the experiment toidentify what you draw. List the organisms you observe in the table you’ve made.Explain your reasons for each identification.A. Next, make a wet-mount slide of the bean water. Place a tiny drop of the beanwater on a blank slide and carefully add a cover slip by touching it to the edge ofthe drop and lowering the cover slip slowly. Check carefully for organisms. Ifnone seem visible, put a drop of crystal violet on the tip of a toothpick. Shakemost of the crystal violet off the toothpick into the staining tray. Gently lift thecover slip and place the toothpick tip covered with crystal violet into the beanwater on the slide. Such a small amount won’t color the water but it will stain theorganisms and help you see them more easily.B. View the wet-mount slide with your microscope and draw what you see. Use thefollowing chart of microorganisms to identify organisms. List the organisms youobserve in the table. Explain your reasons for each identification.C. Determine if each organism is motile or sessile.D. Determine if each organism is a producer or a consumer.Exercise 2: A Pond or Stream Water Micro communityYou will need: Plastic funnel, disposable gloves, lab apron, coffee filter, blank microscope slides,microscope slide covers, crystal violet stain, toothpick, pond or stream water, glass jar- pint-size or larger,safety goggles and microscope.PROCEDURE:1. Wear your laboratory apron and disposable rubber gloves to collect a sample ofwater from a pond or slow moving stream in a pint-size or larger glass jar. Thesource does not need to be of drinkable quality. In fact, a still or even stagnantsource may have a richer micro-community provided there are no contaminants inthe water such as oil or chemical pollutants that might kill the microorganisms. Youshould wear your safety goggles when handling this pond water sample since youdonât know what it contains.2. If you cannot find any surface water, fill a quart or larger container or a bucket withdistilled water or well water, not water that contains chlorine, add a handful of richnatural soil, some leaves or other natural materials you find in your yard, stir, let it sitfor a week, and draw your sample from that water.LabPaq: BK-101 Page 703. Place a coffee filter inside the mouth of the funnel. Place the funnel in a small cleanglass that will suspend the funnel and keep it from falling over but is large enough tohold half a cup of liquid below the funnel mouth,4. Fill the 50-mL graduated cylinder with the collected pond water and slowly pour thewater sample through the filter. Repeat so that at least 100 mL of pond water passesthrough the filter.5. Remove the coffee filter from the funnel after all the water sample has drainedthrough it. Observe if there are any organisms large enough to see withoutmagnification on the filter paper. Quickly draw them for later identification. Turn thecoffee filter inside out and touch the moist tip area with the most collected residuefrom the pond water to a clean glass slide. If the slide is dry, add a drop of pondwater. Carefully apply a cover slip.6. Place the wet mount slide under the microscope. Draw what you see. Use the chartof microorganisms at the end of this experiment to identify organisms; you can alsocheck the websites previously listed for other identification keys for the organisms.List the organisms you observe in the table. Explain your reasoning for eachidentification. If organisms are difficult to see, refer to step #6 in Exercise 1 and usea tiny amount of crystal violet on a toothpick to stain the organisms so theyâll showup more clearly.7. Determine if each organism is motile or sessile, and if each organism is a produceror a consumer.LabPaq: BK-101 Page 71LabPaq: BK-101 Page 72Questions:A. What are possible sources of the microorganisms in the bean water?B. Explain the color differences between the producers and the consumers.C. Are most organisms in the bean water producers or consumers? Are mostorganisms in the pond water producers or consumers?D. Are most producers motile or sessile? Are most consumers motile or sessile?E. Explain the overall differences between the two environments.
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