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Objectives

Students should be able to:

  1. Identify and describe the various laboratory "tools" used by biologists.

  2. Demonstrate the safe, correct operation and data collection using the following instruments: microscope, spectrophotometer, pH meter, electronic balance, and hot plate/stirrer

  3. Demonstrate the safe, correct operation of the following: volumetric pipets and pipettors, vortex mixer, droppers, micropipets, graduated cylinder, dropper bottle, and glassware.

  4. Measure, using the International System of Units (SI), distance, mass, temperature and volume.

  5. Convert measurements within the SI.

  6. Use computer software to construction graphs; produce word documents; do statistical analysis; and gather information from various sources.

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Introduction

The collection and analysis of data is the most important item done by scientists. We can measure many things about the biological world we live in, and to do this we use "instruments" ranging from very simple to very complex. Scientists are bound to the scientific method as the protocol for their studies, and in order to support the various aspect of it, we collect and analyze the data provided by measurements. In this laboratory exercise you will practice using the instruments and devices that will be used in the laboratory to collect and analyze data. This exercise will take two laboratory periods to complete. The second period will be devoted strictly to the correct use of the microscope and preparation of observable materials.

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Pre-lab Activity

In this pre-lab activity you will acquaint yourself with the various types of equipment ("tools") you will be using in the laboratory. You will use photographs and diagrams that allows a visual introduction to the "tools". Click on the "tool" that you want to explore.

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Spectrophotometer

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pH meter

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Electronic Balance

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Hot Plate/Stirrer

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Other Laboratory "Tools"

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Spreadsheets and Materials needed for this Laboratory Exercise

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Pre-Lab Questions  (html version)         Pre-Lab Questions (Word version)

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The Laboratory Activities and Data Collection

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You may do these activities in any order.

Lab Activity #1 - Using the pH meter

Materials:

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pH meter and electrode

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Hotplate / Stirrer

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Stirring bar

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Distilled water bottle

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Tissues

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Plastic cup

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400 mL beakers (2)

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0.1M HCl in dropper bottle

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100 mL Graduated cylinder

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Marking pen

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Spreadsheet for pH Laboratory Exercise

Procedures:

  1. Using the above equipment that was set up and calibrated by the instructor do the following:

  2. Label one 400 mL beaker "distilled H2O" and add 200 mL of distilled water to the labeled beaker. Carefully place into this beaker a stirring bar. (tilt the beaker slightly and allow the stirring bar to slide down the inside of the beaker).

  3. Label the other 400 mL beaker "buffer" and add 200 mL of the buffer solution to the labeled beaker. Carefully place into this beaker a stirring bar. (tilt the beaker slightly and allow the stirring bar to slide down the inside of the beaker).

  4. Place the distilled H2O beaker on the Hot Plate / Stirrer. You will only be using the stirring feature of this "tool". Carefully insert the pH electrode into the solution. The tip of the electrode should be immersed, but NOT touching or interfering with the operation of the stirring bar. Turn on the stirring feature and regulate the speed so it is gently stirring the solution.

  5. Using the directions for using the pH meter, determine the pH of the solution.

  6. Carefully add 1 drop of 0.1M HCl to the solution in the beaker and determine the pH. Record your data on the printed spreadsheet.

  7. Next add another drop of 0.1M HCl and determine the pH. Record your data

  8. Continue doing this until 25 drops and 26 pH measurements have been determined. (0 was the initial pH)

  9. Repeat this process, Steps 6 - 9, using the beaker containing the "Buffer" solution. Record the data each time on the printed spreadsheet.

  10. Graph the data per the instructor's directions.

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Lab Activity #2 - Using the spectrophotometer

Materials:

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Spectrophotometer

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Cuvette containing distilled water (Calibration Cuvette)

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Cuvette containing chlorophyll solution

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Spreadsheet for Spectrophotometer Laboratory Exercise

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Operational Protocol for Using the Spectrophotometer

Procedures:

  1. Calibrate the spectrophotometer using the calibration cuvette which contains distilled water. Follow the protocol previously studied in the pre-lab. Set the spectrophotometer to measure absorbance and the initial wavelength at 400 nm.

  2. Remove the calibration cuvette and insert the cuvette containing the chlorophyll solution. Measure its absorbance at 400 nm. Record the data on the spreadsheet printout.

  3. Remove the chlorophyll solution cuvette and replace it with the calibration cuvette.

  4. Calibrate for absorbance at 410 nm.

  5. Remove the calibration cuvette and replace it with the chlorophyll solution cuvette and determine the absorbance for 410 nm. Record the data on the spreadsheet printout.

  6. Repeat the above procedure, Steps 5 - 7, changing the wavelength by 10 nm each time and calibrating the spectrophotometer for the new wavelength.

  7. Continue until you reach 700 nm. Record the data each time on the printed spreadsheet.

  8. Leave the cuvettes containing the chlorophyll and calibration solutions beside the spectrophotometer so the next group can use them.

  9. Graph the data per the instructor's directions.

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Lab Activity #3 - Using the Electronic Balance

Materials:

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Electronic balance

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"Weighing" paper

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Rectangular solid (or other solid object)

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Sand (or other granular solid)

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Scoopula

Procedures:

  1. Turn on the electronic balance

  2. Open the balance cover lid

  3. Carefully place the rectangular solid (or other solid object) on the balance pan

  4. Close the lid

  5. Determine the mass of the rectangular solid to the nearest 0.01 g. Record your answer here ______________ g.

  6. Remove the rectangular solid from the balance pan

  7. Place a piece of weighing paper on the balance pan. Close the lid.

  8. Mass the weighing paper. Record its mass here ____________ g.

  9. Press Tare, the LCD should read O.

  10. Open the lid and, using the scoopula, place 5.35 g of the granular solid on the weighing paper.

  11. Dispose of the granular solid as per the instructor's directions.

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Lab Activity #4 - Measurement (International System of Units or SI)

Materials:

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15 cm ruler

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Graduated cylinder

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Plastic cup

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Thermometer (C)

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Pipettors

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Pipets

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Small and large culture tubes (10 x 75mm, and 16 x 150 mm)

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Test tube rack

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Pieces of Cardboard

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Objects and materials to be measured

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Conversion chart

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Measurement printout

Procedures:

SI length, volume, temperature, and mass measurements:

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Using the materials provided by the instructor perform the measurements and conversions, and answer the questions found in the printout on Measurement.

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Lab Activity #5: Vortex Mixer, Dropper Bottle

Materials:

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Test tube (16 x 150 mm) filled 1/2 with tap water

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Vortex mixer

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Dropper bottle filled with water

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Plastic cup

Procedures:

Vortex Mixer:

  1. Turn ON the vortex mixer by pressing down the ON/OFF Switch

  2. Hold the test tube at a slight angle on vibrating pad.

  3. Gently push the test tube downward until a vortex forms in the water within the test tube

  4. Practice this procedure until you can do it well. Notice that the harder or easier you press downward on the test tube will determine the rate of mixing

  5. Turn OFF the vortex mixer by pressing down the ON/OFF Switch

Dropper Bottle:

  1. Loosen the dropper in the dropper bottle by gently twisting the bulb at the same time you are pulling up on it.

  2. Lift up the dropper but leave the tip in the bottle and depress the bulb. This will dispense any liquid in it.

  3. With the bulb still depressed put the tip of the dropper down in the liquid in the bottle and release the pressure on the bulb. The dropper will fill with liquid.

  4. Remove the dropper from the bottle. Keep the dropper vertical with the bulb up and the tip down. DO NOT invert the dropper, or tilt it on its side. Bernoulli's Principle still works and the contents of the dropper will not come out until you press on the bulb of the dropper. Dispense the liquid into the plastic cup by depressing the bulb. If you need to remove more liquid, repeat the process.

  5. Do not fill the dropper by continually depressing and releasing the bulb while it is immersed in the liquid

  6. Practice this until you can do it well.

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Post-lab Activity and Data Analysis

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Results and Analysis:

  1. Use the graphs generated for the data collected in the activities for the pH meter and spectrophotometer to assist you in answering the post-lab activity questions.

  2. Turn in the Data Collection section from Measurements; all spreadsheets; all graphs; the conversion chart; operation protocols; and Post=lab Activity Questions. (Due the next laboratory period)

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Post-Lab Activity Questions (html version)         Post-Lab Activity Questions (Word version)

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