Activity 1: Microbial Life in a Water Drop
In this activity students will view the microbial life in three water samples: pond/river, ocean and tap water. They will examine each slide carefully and tally up the organisms found. They will then compare and contrast the samples and formulate an explanation.
Time Needed
90 minutes for lab
Additional time for conclusion
Objectives
Identify the microbes in each sample of water.
Compare and contrast the microbial life in each sample.
Analyze results.
Discuss findings in writing.
Materials (per group of two)
Microscope
Two sets of gloves
Test tube rack
One test tube of each water type
One pipette for each sample
Three slides
Three coverslips
Procedure
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1.
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Make a slide of each sample.
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2.
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Place the sample under the microscope and scan the whole sample beginning with the lowest magnification.
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3.
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Identify the five different organisms: amoeba, paramecium, diatom, cyanobacteria and algae.
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4.
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Describe each organism, its look, shape, movement, etc…
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5.
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Create one data table for all tallies.
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6.
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Record how many of each organism is found.
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7.
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Do the same for each sample.
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8.
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Using the data table write a summary of research findings.
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Activity 2: Photosynthesis
In this experiment students will be able to detect the presence of photosynthesis and respiration as represented by a change in pH. (Adapted from Flinn Scientific, BioFax, Respiration versus Photosynthesis
2 1
)
Time Needed
30 minutes for the initial setup
10 minutes a day for the next four days
Additional time for conclusion
Objectives
Determine the presence or lack of photosynthesis.
Determine the presence or lack of respiration.
Analyze results.
Discuss findings in writing.
Materials (per group of two to four)
Two small jars (baby food jars are the perfect size)
Elodea
Snail
Spring or filtered water (let sit a few days prior to experiment)
Bromthymol blue (BTB) indicator solution, 0.04% aqueous
Pipette (1 mL)
Pre Lab
Demonstrate for students how the BTB indicates pH by using two jars with BTB solution that mimic the experiment, and add a dilute acid to one and dilute base to the other.
Procedure
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1.
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Each group of students will obtain and label two 4 ounce jars and label them #1 and #2. Using a graduated cylinder, students will measure 95 mL of water and pour into each jar.
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2.
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Add 3 mL of BTB to each jar. The color of the water should be greenish.
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3.
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Add 1 sprig of elodea to jar #1.
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4.
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Add 1 snail to jar #2.
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5.
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Create a data table.
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6.
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Record the initial color of each jar.
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7.
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Set both jars in indirect light for one day.
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8.
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On the second day record the color.
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9.
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Then place both jars in a dark area for one day.
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10.
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On the third day record the color.
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11.
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Then place a snail in jar #1 with the elodea and elodea in jar #2 with the snail. Leave both jars in indirect light for one day.
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12.
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On the forth day record the color.
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13.
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Then place jar #1 in a dark place while leaving jar #2 in indirect light, for one day.
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14.
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On the fifth day record the color.
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15.
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Analyze results and discuss findings in writing.
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Discussion
Bromthymol Blue is a pH indicator. When the pH is high the BTB turns blue. When the pH is low the BTB turns yellow. The more dissolved CO
2
in the water the more acidic the water hence a yellow color. The less CO
2
in the water the more basic the water hence a blue color. Photosynthesis, (6CO
2
+ 6H
2
O → C
6
H
12
O
6
+ 6O
2
), takes CO
2
out of the water, whereas respiration (C
6
H
12
O
6
+ 6O
2
→ 6CO
2
+ 6H
2
O + 38ATP), puts CO
2
into the water. Students should be able to infer based on pH levels which metabolic activity is occurring and/or dominant. The following table gives the intended results.
Disposal
The organisms in this experiment cannot be released into the local environment. Please follow the MSDS for proper disposal of the BTB.
Activity 3: Nitrogen Fixing Bacteria
The purpose of this activity is to demonstrate the symbiotic relationship between bacteria and legumes. (Adapted from Bacteria Symbiosis and Nitrogen Fixation, The College of Agriculture and Environmental Sciences, University of Georgia.
2 2
)
Time Needed
30 minutes for the initial setup
10 minutes a day for seven days
Additional time for conclusion
Objectives
Evaluate the role of microorganisms in agriculture.
Determine whether commercial nitrogen or bacterial nitrogen works better.
Analyze results and communicate in writing.
Materials (per group of 2-4)
4 three inch pots (or larger)
Plastic wrap
Soil (pre-moistened)
Alfalfa seeds (not inoculated)
Nitrogen rich fertilizer
Rhizobium leguminosarum
Water
Ruler
Gloves
Procedure
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1.
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Label containers, #1, #2, #3, and #4.
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2.
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Fill each container three quarters of the way with soil.
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3.
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Place four alfalfa seeds into each container.
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4.
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Container #1 is the control, cover seeds with soil only.
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5.
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Container #2, place seeds, cover with soil and add commercial fertilizer.
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6.
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Container #3, place seeds, bacteria over seeds, cover with soil.
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7.
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Container #4, place seed, bacteria over seeds, cover with soil, and add commercial fertilizer.
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8.
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Put a little water in all containers and cover with plastic wrap.
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9.
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When the plants become visible, remove the plastic wrap.
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10.
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Thin out the plants by leaving the strongest two and pulling out the others.
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11.
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The plant height should be measured everyday for 7 seven days and recorded.
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12.
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One plant should be removed and the presence of nodules should be identified and viewed under the microscope. Record all observations.
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13.
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Graph the data, analyze, and summarize findings in writing.
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Discussion
Pay careful attention not to transfer the bacteria into the other two trial systems. Separate trials by keeping all like systems together.
The purpose of trial #4 is to test the response of the bacteria to the presence of nitrogen. Will the bacteria flourish in the presence of nitrogen? Or will they abstain from forming a relationship with the plant roots because nitrogen already exists in the soil?
Activity 4: Phosphate as a limiting factor
The purpose of this lab is to determine the effect of phosphorus containing detergent on algal growth.
Time Needed
30 minutes for the initial setup
10 minutes a day for several days
Time for conclusion
Objectives
Determine if phosphorus is a limiting factor on algal growth.
Demonstrate eutrophication from household wastewater.
Analyze results and summarize in writing.
Materials (per groups of 2-4)
3 wide mouth jars or beakers
Spring water
Dilute dishwasher solution (with phosphate)
Dilute dishwasher solution (without phosphate)
Pond water with algae
Procedure
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1.
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Label containers #1, #2, and #3.
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2.
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Fill each container halfway with algae containing pond water.
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3.
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Using a pipette, sample each container and make a slide.
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4.
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View each slide under the microscope and diagram organism count.
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5.
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Container #1 is the control; add spring water to this container.
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6.
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In container #2 add same amount of dishwasher solution with phosphate.
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7.
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In container #3 add same amount of dishwasher solution without phosphate.
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8.
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Place all containers in a bright location.
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9.
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To measure algae growth, make a slide from each sample and diagram organism count. Do this for several days.
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10.
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Analyze the results and summarize findings in writing.
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Discussion
There should be a notable increase in algae in container #2.
