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BIOL 1407 Lab Manual for Cryer

Student Laboratory ManualBiology 1407 Austin Community College

Introduction

This manual is intended to be primarily an electronic document available on-line. It should be viewed and printed as needed by individual students. Its production has been supported by Austin Community College and Texas Higher Education Coordinating Board.

Our approach in this manual is different from most traditional manuals. We assume that students will work in small groups (“teams”) rather than individually. We expect sharing and pooling of data both within a group and among groups, not individual reports of measurements. Tasks are not presented as techniques to be demonstrated (like recipes to be followed) but rather as group projects to be executed and communicated (like banquets to be served and eaten).

Since Biology 1407 has an extremely challenging prerequisite (Biology 1406), we want this course to reinforce, expand and practice skills already present in students’ intellectual toolboxes. Students are expected to “bring to the table” all these skills: basic use of light microscope including quantitative measurements, micro-liter scale volumetric measurements, preparation of chemical solutions and quantitative dilution techniques, usage of electronic spreadsheets, basic graphing and data analysis (including linear regression). Various places in this manual refer students to their Biology 1406 laboratory manual for review. (That manual, like this one, is available on-line.)

We also assume that (modest) modern computer-based tools will be available in labs. These tools include: computers with word processing and spreadsheet software, live internet connections at high speed, microscopes with digital photo microscopy. Our students should learn to think of these as fundamental tools in biological research.

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Each exercise is presented in three parts. Part 1 is a very brief introduction to the exercise. Part 2 is a series of things to complete on line before class meeting, which includes taking a pre-lab quiz on Blackboard. Part 3 presents a series of tasks to complete during the lab period and cleanup instructions.

The instructions are generally not detailed because student teams need to learn to direct their own work. Student teams should learn to organize their work, execute it, and then communicate it. Students are expected to develop intellectual independence of their instructor and instructors are urged to wean students from “hand holding” with regard to directions. Students should learn to “make it happen”, not simply to follow step-by-step instructions. Of course, procedures involved in "making it happen" must be subject to scrutiny (preferably of colleagues) and reported accurately.

We have attempted to provide, when appropriate, local relevance for these labs by choosing example organisms that occur in Texas and that, in some cases, have economic importance in our state.

One project will require multiple weeks to complete. In doing this, students will be exposed to time frames for data acquisition that are longer than a few hours and to illustrate biological phenomena that unfold more slowly than typical lab exercises permit.

Another inclusion in this manual is phenomena of populations. While traditional lab manuals for such courses focus on individuals, we attempt here to direct students’ descriptions and examinations to populations of individuals.

We hope that ACC students will use this biology class as a vehicle for bringing multiple technological abilities (photography, calculations, information acquisition, cell phone use, etc) to bear on biological challenges. We want society’s convergence of technologies to accelerate in our classroom and we expect our students to lead society in this endeavor.

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Table of ContentsLab 1 Safety Training and Equipment Orientation 4

Lab 2 The Art of Making Scientific Observations 6

Lab 3 Concepts of Relatedness 9Preparation for Prokaryote Lab

Lab 4 Prokaryotes 14

Lab 5 Protists 18

Lab 6 Euglena Lab 20

Lab 7 Mosses, Ferns and Lycopods 22

Lab 8 Conifers and Flowering Plants 25

Lab 9 Flowering Plant Anatomy 29

Lab 10 Fungi 31

Lab 11 Sponges, Cnidarians and Platyhelminths 33

Lab 12 Mollusks and Annelids 37

Lab 13 Arthropods 41

Lab 14 Chordates 44

Lab 15 Chemical Signals 47

Lab 16 Electrical Signals and Nervous Systems 49

BIOL 1407 Appendices for Laboratory Projects

Appendix 1 Illustrating Biological Material 58Appendix 2 Maintaining Laboratory Notebooks and Related Records 62Appendix 3 Using “Prepared” Slides 63Appendix 4 Reading a Vernier Scale 65Appendix 5 Constructing Graphic Displays of Data 66Appendix 6 Using ACC’s “Blackboard” Program 72Appendix 7 Measuring an Area of Irregular Shape 73 Appendix 8 Using Our Spectrophotometers 74Appendix 9 Interpreting Absorbance Spectra 75

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Lab 1: Safety Training and Equipment Orientation

I. Brief Background

Modern biological research almost always requires teams of scientists to work together while sharing both facilities and information. Without delay, you need to form a lab “team”, learn our school’s standard practices (protocols) and establish effective communications.

II. Pre-lab assignment

1. Review the following materials from Biol 1406 labs:

Use of light microscope http://www.austincc.edu/biology/labmanuals/140612th/12th1406lab03.pdf http://www.austincc.edu/biology/labmanuals/140612th/12th1406lab04.pdf

Keeping a lab notebookhttp://www.austincc.edu/biology/labmanuals/140612th/12th1406labappA.pdf

2. Review the following appendices to this lab manual:

Appendix 1 Illustrating Biological MaterialAppendix 2 Maintaining Laboratory Notebooks and Related RecordsAppendix 3 Using “Prepared” SlidesAppendix 4 Reading a Vernier ScaleAppendix 5 Constructing Graphic Displays of Data Appendix 6 Using ACC’s “Blackboard” program

3. After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s directions.

III. Student Tasks

1. Participate in ACC safety training and sign official roster of persons allowed to perform laboratory work in your lab room.

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http://www.austincc.edu/biology/labmanuals/140612th/12th1406labappA.pdf

http://www.austincc.edu/biology/labmanuals/140612th/12th1406lab04.pdf



2. Get a "Student Skills Form" from your instructor. Fill it out. Mingle with the other students until you have found a group of people that you think you can work with and who have different skill groups. Assemble your lab “team”. In general, it will be useful to have team members with differing sets of skills.

3. Once your team is formed, come up with a team name. Tell your instructor the names of all team members and the team name. Your instructor will set up a group for you on Blackboard for file exchanges and intra-team communication.

4. All team members should demonstrate to their entire team that they have competence in the techniques listed below. Most students will be more comfortable with some techniques than others, but mutual instruction and coaching is expected until all have competence in every technique.

Today’s exercise should be a review of most these materials, but some parts are likely to be unfamiliar. Lab teams need to work together to establish confidence in all team members’ competences. During today's lab, all students are expected to use all the following equipment, techniques and software.

1. General use of compound microscope. Get a prepared slide and show your ability to properly focus, adjust lighting, use mechanical stage, change magnification, and determine total magnification.

2. General use of dissecting microscope. Get a prepared slide of a fluke and a shell from your instructor. Demonstrate your ability to properly focus, set lighting appropriate to the specimen, and determine total magnification.

3. General use of digital camera to make photographs. Have all team members take photographs of prepared slides using both compound and dissecting microscopes. Take photographs of the shell and other large objects.

4. Get an object from your instructor. Demonstrate that all team members can use the Vernier scale to accurately measure the dimensions of the object.

5. Upload photographs to group file exchange in Blackboard

6. General use of desktop computer with internet connection

7. General use and access to Blackboard classroom software

8. Cleanup your lab space.

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Lab 2: The Art of Making Scientific Observations

I. Brief Background

Making observations is an essential part of a scientist's work. Some branches of science rely heavily, if not exclusively, on observation. Just think about astronomy, for example. For experiments and experimental work, observations play a role in the background work that leads to research questions, developing hypotheses, and designing experiments. Data collection relies on good observations. The goal in this lab is to learn to how to make good observations, to consider population characteristics instead of individual, and to use simple descriptive statistics to summarize your observational data.


1. Review scientific inquiry in the textbook, Chapter 1, pages 18-24.

2. Review the following materials from BIOL 1406 labs:

Collection and Analysis of Datahttp://www.austincc.edu/biology/labmanuals/140612th/12th1406lab01.pdf

Use of Excelhttp://www.austincc.edu/~emeyerth/exceltutor1.htmhttp://www.austincc.edu/~emeyerth/exceltutor2a.htmhttp://www.austincc.edu/~emeyerth/excel3.htm

Mean and Standard Deviationhttp://www.austincc.edu/biology/labmanuals/140612th/12th1406labappB.pdf

Graphing Datahttp://www.austincc.edu/biology/labmanuals/140612th/12th1406labappE.pdf

3. Review the following appendices to this lab manual:Appendix 1 Illustrating Biological MaterialAppendix 2 Maintaining Laboratory Notebooks and Related RecordsAppendix 4 Reading a Vernier ScaleAppendix 5 Constructing Graphic Displays of Data Appendix 6 Using ACC’s “Blackboard” program

4. After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s directions.

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http://www.austincc.edu/biology/labmanuals/140612th/12th1406labappE.pdf

http://www.austincc.edu/biology/labmanuals/140612th/12th1406labappB.pdf

http://www.austincc.edu/~emeyerth/excel3.htm

http://www.austincc.edu/~emeyerth/exceltutor2a.htm

http://www.austincc.edu/~emeyerth/exceltutor1.htm



III. Student Tasks

Task 1: Making ObservationsYour group will be looking at Turritella snail shells. You will need the

following materials:A package of shellsCalipersBalanceWeigh boatsSketching materialsLaptop computerDigital camera and accessories

Your group needs to complete the following tasks:

1. For each shell type, make a sketch of a representative specimen and make written observations. A sketch should have the name of the artist and the date. Sketches should also include scale. Handwritten observations should also include information on name and date.

2. Take a representative specimen of each shell and examine them with the dissecting microscope. Make sketches and take photographs of each through the microscope. (Note: be sure and record TM for all photographs and sketches made with microscope.)

3. For each shell type, line up the shells and take a picture of the group.

4. Make written observations of the shells. Summarize the variation within each type of shell. Compare the two species (shell types) by looking at similarities and differences.

5. Set up an Excel spreadsheet for each shell type to record this data: shell length shell width shell weight

6. For each type of shell, take a photo of one shell and show with labels how you measured length and width.

Note: you can use your own Photoshop software, the drawing tools in any Microsoft Office product (such as Word or Powerpoint), Paint or any other software that you have access to. However, check to make sure that your file will open up in Microsoft Office 2003 when it is posted to Blackboard.

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7. Collect all data for each shell in your two packages and record in data tables.

8. For each shell type, calculate descriptive statistics for each measurement:

average (mean) standard deviation range

9. For each shell type, make these graphs in Excel: scatter plot of length vs. width (Note: length is x axis) histogram of shell length (Note: continuous variables; bars touch) histogram of shell width histogram of shell weight

10. Upload your preliminary materials (observations, sketches, photographs, data tables, spreadsheets, graphs) into Blackboard file exchange for your group before lab is over. For sketches and handwritten observations, you can either scan the material or take a photograph. Every member of your group will then have access to the information to use in preparing their individual electronic lab notebook entries.

Clean up procedures for this lab: Put the shells back into their respective bags. Put all materials and equipment back where you found it.

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Lab 3: Concepts of RelatednessPreparation for Lab 4

I. Brief Background

To say that organisms or groups of organisms are “related” has meant different things in the history of biology and still can mean different things in different contexts today. In this exercise, students are to explore what “being related” means in two different contexts: anatomical similarity and protein amino acid sequence similarity. (What obvious potential point of comparison are we ignoring here?)


1. Students need to be aware of “FASTA” format for amino acid and nucleotide sequences. Visit an online encyclopedia for a brief introduction.

2. Students need to be aware of the ExPASy (Expert Protein Analysis System) proteomics server of the Swiss Institute of Bioinformatics (SIB). Visit http://ca.expasy.org/ and note its search engine near the top of its homepage. One can enter both protein names and generic epithets to search for a protein’s report within a genus. Complete protein names and binomials sometimes score a hit, too.

3. Students need to be aware of software that compares sequences of amino acids and/or nucleotides. Visit http://align.genome.jp/ and notice the box that accepts FASTA sequences for comparison. (Multiple sequences should be entered at once, but all must be entirely in FASTA.) To actually execute the comparison, scroll to bottom of the page and “Execute Multiple Alignment”.

4. After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s general directions.

III. Student Tasks

Task 1: Molecular-Based Phylogenetic TreesWe are going to use amino acid sequences to draw phylogenetic trees that

show possible evolutionary relationships among selected taxa. Keep in mind that your phylogenetic tree will be based only on one protein sequence. We have chosen to use "cytochrome c oxidase subunit 1". It has been sequenced for many organisms and it is a good marker for phylum-level evolutionary relationships because it is a conservative protein.

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http://align.genome.jp/

http://ca.expasy.org/

http://www.isb-sib.ch/

http://en.wikipedia.org/wiki/Proteomics


Use the ExPASy search engine to find protein amino acid sequences. Search the top-listed data base; use the phrase “cytochrome c oxidase subunit 1” followed by the generic epithet. Then, choose carefully from among the hits to make sure you have a complete sequence. Use the checklist on the next page to help you make sure you have collected the correct data.

After finding a complete sequence, get it in FASTA (scroll to bottom of page). Save each sequence in a word processing document. Add each sequence to the document as you acquire them. Do not add any extra information to the document.

Once you are finished with the document, enter all the sequences at once into alignment software at http://align.genome.jp/ . Cut and paste to do this. After alignment results are reported, scroll to the bottom of the results page. Have a “Dendrogram with branch length” drawn for you. You will need to print your dendrogram as well as your FASTA document in order to label your dendrogram with confidence.

With your electronic lab notebook posting, you will need to include a labeled dendrogram that shows the name of each branch. The original dendogram will only show an abbreviation for the taxa. Write in the complete genus or species name. Then, scan or photograph your dendrogram so it can be uploaded.

Compare your dendrogram to the information in the textbook. Are there any unexpected differences? If so, what are some plausible reasons for the differences?

Task 2: Preparation for Lab 4 – ProkaryotesWe are going to study prokaryotes next week. Since agar plates need

time to incubate, we are going to start them this week and look at them next week. There are two parts to this exercise:

aerial samples to see the numbers and types of prokaryotes and other microorganisms in the air

habitat samples to see the numbers and types of microorganisms found on surfaces and in the environment of the campus

Your group needs the following materials:4 petri dishes containing nutrient agarSharpieTransparent tapeSterile cotton swabs and/or plastic pipettes. Cotton swabs work best for

solid surfaces while pipettes work best for liquid samples.Sterile water (for wetting cotton swabs before swabbing dry surfaces)

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http://align.genome.jp/


1. Prepare your aerial sample. Label the bottom of one petri dish with a Sharpie. Write close to the edge and include the following information:

Group name Date “Aerial sample”

Put the petri dish on a counter on the side of the room. Take the top of the petri dish off. Leave it exposed to the air for one hour. Then, put the lid back on the petri dish and tape it shut. Incubate the petri dish bottom side up (agar side up) at room temperature for seven days.

2. Prepare your habitat samples. Choose three habitats within the room or campus environment that you would like to sample. These habitats can be parts of people’s bodies or cell phones or whatever. Use your imagination! Keep track of the habitats you’ve chosen.

Label the bottom of each petri dish with a Sharpie. Write close to the edge and include the following information:

Group name Date "Habitat sample” Type of habitat (you should have one petri dish for each habitat).

Sample each habitat once, using separate swabs or pipettes for each sample you take. When finished, tape the dishes shut and incubate bottom side up (agar side up) at room temperature for seven days.

To sample with a swab:Dampen the swab with sterile water. Lightly roll the swab over the surface

to be sampled. Open the petri dish slightly and lightly roll the swab over the surface of the nutrient agar. Don’t jab the swab into the agar. Quickly put the lid back on the petri dish.

To sample with a pipetteCollect a few drops of liquid with the sterile pipette. You don’t need a

whole pipette full, just a few drops. Remove the lid of a petri dish, quickly add the drops of fluid to the petri dish, and put the lid back on. Swirl the dish to form a thin film of the liquid on the surface of the agar. Keep the dishes top side up for at least 30 minutes before turning them upside down to incubate them.

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Task 3: Vertebrate Forelimb Skeletal AnatomyUse the vertebrate skeletons in lab to compare forelimb skeletal anatomy in:

● Frog (Rana) ● Rat (Rattus)● Cat (Felis)● Human (Homo)● Pigeon (Columba)● Bat

You need to identify these bones in each skeleton:● Humerus● Radius● Ulna● Carpals● Metacarpals● Phalanges

You will need your photo atlas to help you with this. Please note that some bones may be fused or reduced in size. When fusion occurs, the name of the fused bone usually reflects its parts, such as radioulna. In those cases, you need to know the modified names.

Photograph and/or sketch forelimb skeletons for each animal. Make written observations about similarities and differences among the forelimbs. Upload your preliminary information into Blackboard file exchange for your group.

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Checklist of Organisms

Genus (common name) Verify entry matches name

Verify protein name matchesCytochrome c oxidase subunit 1 (Watch for and exclude subunit 2,

subunit II, fragment, etc.)

Verify this is not a

report of a fragment

# of amino acids in protein

(unprocessed)

Anabaena

Anas (duck)

Arabidopsis

Artemia

Bos taurus (cow)

Brassica

Bufo (toad)

Canis familiaris (dog)

Canis latrans (coyote)

Crocodylus (crocodile)

Drosophila (fruit fly)

Euglena

Felis (cat)

Gallus (chicken)

Glycine (soybean)

Homo (human)

Leptotyphlops (Texas blind snake)

Macropus (Wallaroo)

Myotis (bat)

Nostoc

Oryza (rice)

Pantherophis (corn snake)

Paramecium

Penicillium

Phascolarctos (Koala)

Physarum

Pleurotus (oyster mushroom)

Rana (frog)

Rattus (rat)

Sceloporus (western fence lizard)

Solanum lycopersicon (tomato)

Triticum (wheat)

Xenopus (African frog)

Zea (corn)

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Lab 4: Prokaryotes

I. Brief Background

The first living things were prokaryotes. Prokaryotes shaped our planet’s chemistry. Prokaryotes served as the actual building blocks for eukaryotes. Prokaryotes may be tough enough to survive blasts into space. Prokaryotes exhibit dazzling variety in their nutritional patterns. A few prokaryotes generate much human misery, but without prokaryotes humans would not exist to experience misery (or other conditions).

Briefly consider some connections between these organisms and Texas. http://www.utexas.edu/news/2008/04/23/biofuel_microbe/ http://repositories.tdl.org/tdl/handle/1969.1/2235 http://www.utmbhealthcare.org/Health/Content.asp?PageID=P02201 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm56d730a1.htm http://texashelp.tamu.edu/004-natural/disease-and-epidemic.php

Biologists are generally expected to recognize certain types of microbial life under a microscope and students should acquire sight recognition ability of all major groups covered in this lab manual.


After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s general directions.

III. Student Tasks

Safety Notes:1. Use gloves when handling petri dishes after they have been inoculated with

microorganisms.2. Do not open petri dishes after they have been inoculated.3. Dispose of petri dishes and any gloves that are accidentally exposed to

microorganisms in the biohazard bag when you are finished recording data.4. Disinfect tables after disposing of petri dishes.

Task 1: Aerial and Habitat SamplesLast week, you started agar plates. Today, your group is going to look at

the plates. The plates have been incubated for seven days at room temperature.

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http://texashelp.tamu.edu/004-natural/disease-and-epidemic.php

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm56d730a1.htm

http://www.utmbhealthcare.org/Health/Content.asp?PageID=P02201

http://repositories.tdl.org/tdl/handle/1969.1/2235

http://www.utexas.edu/news/2008/04/23/biofuel_microbe/


1. On the aerial and habitat samples, observe the microorganism colonies that have grown on the agar. DO NOT OPEN THE DISHES. Since we do not know what these microorganisms are, you should not expose everyone in the room to them! Use gloves when handling the dishes.

2. Sketch or photograph your samples. Describe the colonies, using general terms such as color of the colony, relative size (tiny, small, huge, etc.), texture (rough, smooth, shiny, wrinkled).

3. Dispose of petri dishes and contaminated gloves in the biohazard bag.

Principles of Bacterial Colony Morphology

When a single bacterial cell is deposited on the surface of a nutritive medium, it begins to divide exponentially. After thousands (up to billions) of cells are formed, a visible mass

appears. This mass of cells is called a colony. Each species of bacterial or fungal organism will exhibit characteristic colonies.

This info is taken from the Microbugz web site at: http://www.austincc.edu/microbugz/

Task 2: Living Prokaryotes in YogurtAn easy way to see living bacteria is to look in yogurt containing live

bacterial cultures. This is also a good opportunity to see different bacterial shapes and arrangements. The three most common bacterial cell shapes are coccus (round little balls; pl. cocci), bacillus (rod-shaped cells; pl. bacilli) and spirillum (cells twisted into S-shapes; pl. spirilla). Some common arrangements are chains (strepto-) and irregular clusters (staphylo-). The names for these shapes are often part of the scientific names of bacteria, such as Staphylococcus aureus and Bacillus anthracis.

Caution: When looking at the yogurt culture, if you see spirilla, you are not paying attention or you need to check your focus or lighting.

Your group will need the following materials:Clean microscope slide and cover slipToothpickYogurt cultureDropper bottle of waterCompound microscope

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http://www.austincc.edu/microbugz/


Take a very small (tiny) yogurt sample by dipping the tip of the toothpick into the yogurt. Transfer the yogurt to your microscope slide. Add a drop of water. Mix the yogurt and water with the toothpick. Put a cover slip over the yogurt smear. Observe the bacteria by looking at the thinnest portion of the smear with the microscope. (You’ll have to go to high power to see the bacteria.) If you have trouble seeing the bacteria, adjust the light with the iris diaphragm.

Document the bacteria you see with either sketches or photographs. Identify the shape for each type that you see. Make written observations.

Task 3: Cyanobacteria Cyanobacteria are an important group of common bacteria. They carry

out oxygenic photosynthesis in basically the same way plants do. Most can fix nitrogen (convert atmospheric nitrogen to ammonia), which means they can make their own fertilizer if they have to. Consequently, cyanobacteria have some of the simplest environmental needs of any organism. Give them light and air (which contains carbon dioxide and atmospheric nitrogen) and they can live pretty well without almost anything else. Cyanobacteria were the first organisms to evolve oxygenic photosynthesis, so they can take credit for changing the atmosphere from one relatively free of oxygen to one with enough oxygen for you and the rest of us aerobic organisms to survive.

You’ll be looking at a couple of cyanobacteria genera: Oscillatoria and Nostoc.

Oscillatoria is a freshwater cyanobacterium, a typical pond-scum inhabitant. Its basic form is a filament (a thread) of individual cells attached to one another. When you observe it, keep an eye out in case it moves.

Nostoc is a terrestrial cyanobacterium. To stay active and continue carrying out photosynthesis, Nostoc secretes huge quantities of a gelatinous carbohydrate around its filaments. The carbohydrates absorb water and keep the cells moist. This makes Nostoc the jolly green jelly ball organism! Unlike Oscillatoria, Nostoc filaments often contain more than one type of cell. Most are normal, contain the blue-green photosynthetic pigments, and carry out photosynthesis. Others are larger, paler and have very thick cell walls. These cells are called heterocysts and they carry out nitrogen fixation. So Nostoc is capable of some cellular division of labor, which means that Nostoc can be considered a very simple multicellular organism.

Your group will need the following materials:Oscillatoria and Nostoc culturesClean microscope slides and cover slipsPipetteBalance and weigh boats

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Remove a few strands of Oscillatoria from the culture. Make a wet mount. Observe the Oscillatoria under low and high power. Document with sketches or photos. Make written observations.

Observe the dried Nostoc culture. Document with sketches or photos and make written observations.

Weigh a piece of dried Nostoc in a weigh boat. Keep it in the weigh boat and add water to hydrate it. After 20 minutes, pour off any water that has not soaked in and reweigh the Nostoc. Make sure you record your data and document any changes in appearance.

At this point, we are not going to keep telling you to document with photographs or sketches and take written observations. You will be continuing to do this throughout the rest of the semester, so get in the habit of doing so now.

Use forceps or probes to pull off a small piece of the rehydrated Nostoc. Make a wet mount and examine under low and high power. You will probably have to flatten the slide. If so, put a paper towel over the cover slip and pressing firmly with your thumb. Don’t press so hard you break the slide or cover slip! You may have to add a little more water afterward; do so at the edge of the cover slip while it is still on the slide.

Clean up procedures for this lab:Dispose of all slides and glass coverslips in the glass sharps container. If

coverslips are plastic, they may be thrown away in the regular trash.

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Lab 5: Protists

I. Brief Background

“Protista” is falling from use as a kingdom name; nonetheless, it is a useful term for a very large group of organisms. This polyphyletic assemblage can be divided (for beginners) into autotrophs and heterotrophs. This lab introduces students to some famous autotrophic and heterotrophic “Protists”.

Briefly examine these links to some of Texas’ autotrophic “Protists”.http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/redtide/http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/otherhab/http://www.physorg.com/news100350969.html (note wavelengths)http://www.baysfoundation.org/archives_07_10_Sargassum.phphttp://www.dshs.state.tx.us/idcu/disease/amebiasis/faqs/http://www.dshs.state.tx.us/idcu/disease/malaria/faqs/http://www.cdc.gov/mmwr/preview/mmwrhtml/00036836.htmhttp://www.dnr.state.mn.us/volunteer/janfeb03/slimemolds.htmlhttp://handsontheland.org/monitoring/projects/slimemolds/slimemolds.cfm


After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s general directions..

III. Student Tasks

Task 1: Autotrophic Protists Document these autotrophic protists and label indicated structures.

Phylum Bacillariophyta Mixed diatoms (freshwater or marine)

Phylum Dinoflagellata Ceratium

Phylum Euglenida Euglena eyespotchloroplastsflagellum

Trypanosoma flagellum

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http://handsontheland.org/monitoring/projects/slimemolds/slimemolds.cfm

http://www.dnr.state.mn.us/volunteer/janfeb03/slimemolds.html

http://www.cdc.gov/mmwr/preview/mmwrhtml/00036836.htm

http://www.dshs.state.tx.us/idcu/disease/malaria/faqs/

http://www.dshs.state.tx.us/idcu/disease/amebiasis/faqs/

http://www.baysfoundation.org/archives_07_10_Sargassum.php

http://www.physorg.com/news100350969.html

http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/otherhab/

http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/redtide/


Phylum Chlorophyta Volvox vegetative cellsdaughter colonies

Phylum Phaeophyta Sargassum or Fucus or Laminariabladestipeholdfast (if present)air bladders (if present)

Task 2: Heterotrophic Protists Document these heterotrophic protists and label indicated structures.

Phylum Ciliophora Paramecium ciliaoral groovecontractile vacuolefood vacuole

Stentor macronucleus

cilia

Phylum Apicomplexa Plasmodium red blood cells: infected and uninfectedmerozoites

Phylum Rhizopoda Amoeba pseudopodianucleus (if visible)

Phylum Myxomycota Physarum plasmodiumlook for cytoplasmic streaming

Clean up procedures for this lab: Dispose of all slides and glass coverslips in the glass sharps container. If

coverslips are plastic, they may be thrown away in the regular trash.

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Lab 6: Euglena Population Assay

I. Brief Background

Euglena, a well-known photosynthetic protist, grows easily in laboratory culture. As cultures age, their color darkens and it is reasonable to assume that intensity of cultures’ color is related to population density of Euglena cells.

Microbial life generally is studied by biologists in populations, not as individuals. We often speak of “population density” or “cell density”; this, of course, is number of cells per unit of volume.

Students should have already located some information sources relevant to this organism during their “Meet Some Organisms” laboratory exercise.

Take a brief look and see what this site has to say about Euglena—perhaps you can think of a practical use for your Euglena assay http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/otherhab/


1. Read this entire lab project and discuss it with your teammates, making initial assignments of tasks and responsibilities.

2. Review the following materials from Biol 1406 labs and this manual http://www.austincc.edu/biology/labmanuals/140612th/12th1406lab02.pdf

Appendix 8: Using our SpectrophotometersAppendix 9: Interpreting Absorbance Spectra

3. After studying relevant material in your textbook and other information sources, visit the “Blackboard” site for your class and complete this lab’s pre-lab quiz according to your instructor’s general directions. Check your answers when you finish, of course.

4. Before arriving at lab, review all equipment listed under “IV. Recommended Equipment…” and make sure someone in your team is familiar with all items listed.

III. Student Tasks

Task 1: Design a ProcedureUsing a spectrophotometer and a standard curve, develop a technique to

determine population density in Euglena cultures. After developing your technique, describe it in a way that can be reliably replicated by others—you

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http://www.tpwd.state.tx.us/landwater/water/environconcerns/hab/otherhab/


should produce a written set of instructions describing your technique for distribution to your entire class (one set of instructions from each team).

Available equipment should include: established Euglena cultures, micropipettes with tips, ordinary 5mL glass pipettes, culture medium for Euglena, spectrophotometers with cuvettes, microscopes with microscope slides, glassware, vortex mixers, test tubes.

Euglena do not “like” distilled water. Use spring water or aquarium water instead of distilled water, if you want water for dilutions.

Biologists sometimes use stains on material being examined. Sometimes stains are highly specific for substrate and other stains are broad in the kinds of substances to which they attach. Stains often are hazardous and biologists should wear gloves when handling them. Slides and materials containing hazardous stains need to be treated as hazardous waste; the volume of this material is generally quite small.

Task 2: Implement Your ProcedureAfter developing an assay technique, each group will be given a culture of

unknown cell density and asked to determine its population density and approximate total population.

Clean up procedures for this exercise: these materials are generally non-hazardous; disposable glass goes into broken glass container; excess solutions go down sink; other materials go in ordinary trash. Equipment should be returned to storage settings and returned to storage location. Any saved materials must be clearly labeled with group name, date, and content description. Unlabeled materials will be discarded by lab assistant or instructor.

Remember that test tubes and cuvettes look similar, but they are radically different in cost. Test tubes are disposable (cheapest quality glass) while cuvettes are carefully cleaned and reused. They should be rinsed with distilled water, wiped with soft chem-wipes (not paper) and saved.

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Lab 7: Mosses, Ferns and Lycopods

I. Brief Background

Polytrichum (or Mnium) is used here as a representative of the phylum Bryophyta. Students should know general characteristics of this phylum and additional examples of organisms in it.

Common garden ferns or specific genera (such as Cyrtomium, Polypodium, Thelypteris or Ceratopteris) are used here as representatives of the phylum Pteridophyta. Students should know general characteristics of this phylum and additional examples of organisms in it.

Selaginella is used here as a representative of the phylum Lycophyta. Students should know general characteristics of this phylum and additional examples of organisms in it.

Students should understand plants’ “alternation of generations” and understand how it varies among these phyla. Which tissues are haploid? Which are diploid? What roles are played by mitosis, meiosis, syngamy (union of gametes)?

Students are cautioned that true plant stems sometimes occur underground (rhizomes) and true plant roots sometimes occur above ground. “Rhizomes” sometimes are confused with “rhizoids”; rhizoids are single cells; rhizomes are stems and therefore quite complex in structure.

Furthermore, leaves can be compound and portions of a compound leaf can be mistaken for stem. A beginning student should look for a good definition of “leaf”, “stem”, and “root”.

Use this search engine to locate natural occurrences of these organisms in Texas (positive search results usually include a link to distribution maps):

http://plants.usda.gov/checklist.html



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III. Student Tasks

Task 1: Mosses Examine the different mosses that are available in lab. Locate and label

indicated structures and generations. Document your observations.

Gametophyte generationSporeProtonemaPhyllids (leaf-like structure)Caulid (stem-like structure)RhizoidsGametangium (gametangia) Antheridium (antheridia) Archegonium (archegonia)Calyptra (old archegonium)

Sporophyte generation Embryo Stalk (seta) Capsule (sporangium) Peristome

Task 2: Ferns Examine the different ferns that are available in lab. Locate and label


Sporophyte generation Embryo Vascular tissue Stem Roots Leaves (simple or compound? Vascular tissue present?) Fiddlehead Sporophylls and vegetative leaves Sorus (sori) Sporangium (sporangia) with stalk and annulus

Gametophyte generation Spores Young prothallus (prothallia) Mature prothallus Gametangium (gametangia) Antheridium (antheridia) Archegonium (archegonia)

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Task 3: Lycopods Examine the different lycopods that are available in lab. Locate and label


Sporophyte generation Vascular tissue Stem Roots Leaves (simple or compound? Vascular tissue present?) Strobilus (strobili) (= cones) Sporophylls

Microsporophylls Megasporophylls Vegetative leaves Sporangia

Microsporangia Megasporangia

Gametophyte generation Spores

Microspores Megaspores

Male gametophyte (= microgametophyte) may not be available Female gametophyte (= megagametophyte) may not be available

Clean up procedures for this lab: Put everything back in its proper place. If you made wet mounts, dispose

of the slides and glass coverslips in the broken glass container. Plastic coverslips may be discarded in the trash.

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Lab 8: Conifers and Flowering Plants

I. Brief BackgroundPinus is used here as a representative of the phylum Pinophyta

(Coniferophyta). Students should know general characteristics of this phylum and additional examples of organisms in it.

Lillium (or Brassica or Glycine) is used here as a representative of the phylum Magnoliophyta (Anthophyta). Students should know general characteristics of this phylum and additional examples of organisms in it.

Students should understand plants’ “alternation of generations” and understand how it varies among these phyla. Which tissues are haploid? Which are diploid? What roles are played by mitosis, meiosis, syngamy (union of gametes)?

Use this search engine to locate natural occurrences of this organism in Texas (positive search results usually include a link to distribution maps):

http://plants.usda.gov/checklist.html http://www.fs.fed.us/pnw/pubs/pnw_rp389.pdf



III. Student Tasks

Task 1: Conifers Examine the different conifers that are available in lab. Locate and label


Sporophyte generation Stem

Roots Leaves

Strobili (= cones) Microspore-producing cone (= pollen cone) Megaspore-producing cone (= ovulate cone = seed cone)

Sporophylls Microsporophylls Megasporophylls

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http://www.fs.fed.us/pnw/pubs/pnw_rp389.pdf



Sporangia Microsporangia Megasporangia (= ovules ≠ eggs) Integuments

Micropyle

Gametophyte generation Spores

Microspores Megaspores)

Male gametophyte (= pollen = microgametophyte) Female gametophyte (= megagametophyte) inside ovule Archegonium

Seed structures Note genetic status of each:

Old sporophyte, female gametophyte, new sporophyte Megagametophyte Embryo Cotyledons (how many?) Hypocotyl Radicle Seed coat

Task 2: Flowering Plants Examine the different flowering plants that are available in lab. Locate

and label indicated structures and generations. Document your observations.

Sporophyte generationStemRootsLeaves Strobili (flowers) – see section below Sporophylls

Microsporophylls (= stamens)Megasporophylls (= carpels)

Sporangia Microsporangia (= anthers) Megasporangia (= ovules)

Integuments Micropyle

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Gametophyte generationSpores

Microspores Megaspores)

Male gametophyte (= microgametophyte = pollen) Female gametophyte (= megagametophyte) inside ovule

7 cells 8 nuclei including egg and endosperm mother cell

Flower parts (all sporophytic) SepalsPetalsMicrosporophylls = stamens (collectively, the androecium)

Anther (= microsporangium) Filament

Megasporophylls = carpels StigmaStyleOvary

Ovules (= megasporangia ≠ eggs) with integuments and micropyle

Dissect a flower and identify each part.

Fruit Ovary wallSeeds

Dissect all fruits available and identify each part.

Bean Seed, soakedNote genetic composition of all tissues

EmbryoHypocotylRadicleSeed coat

Put on gloves and safety eyewear. Dissect a bean seed into two parts. Soak bean seed half with iodine. Look for the cotyledons (how many?). Where's the endosperm?

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Corn Seed, soaked Note genetic composition of all tissues

EmbryoHypocotylRadicleSeed coatPut on gloves and safety eyewear. Dissect a corn seed into two parts. Soak corn seed half with iodine. Look for the cotyledons (how many?). Where's the endosperm?

General dissecting equipment includes: sharp probe, dull probe, sharp blade, forceps, scissors, water with dropper, paper towels, blank microscope slides, cover slips, dishes to hold organisms and materials under dissecting microscope, ruler, pins.

Biologists sometimes use stains on material being examined. Sometimes stains are highly specific for substrate and other stains are broad in the kinds of substances to which they attach. Stains often are hazardous and biologists should wear gloves when handling them. Slides and materials containing hazardous stains need to be treated as hazardous waste; the volume of this material is generally quite small.

Clean up procedures for this lab: Dispose of dissected seeds, fruits, flower parts, and gloves in the general

trash. Put excess iodine used to stain seeds in chemical waste disposal. Return all equipment and specimens to their proper places.

All dissecting equipment, including pins, must be washed and dried before stowing. Clean off your desks with Lysol or appropriate cleaning solution.

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Lab 9: Flowering Plant Structures

I. Brief Background

Several flowering plants, such as Ranunculus, are used here as representatives of the phylum Magnoliophyta (Anthophyta). The structures examined in this lab are from a major clade of flowering plants, the eudicots.



III. Student Tasks

Task 1: Roots Examine the specimens and slides. Identify the structures.

Radish rootsRoot hairsTap root

Root apical meristem Root capApical meristemZone of cell divisionZone of elongationZone of maturation (if visible)

Eudicot root cross sectionEpidermis

Root hairsCortex

EndodermisPericycle

Vascular bundle Xylem Phloem)

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Task 2: Shoots Examine the specimens and slides. Identify the structures.

Basil Plants (or other plant)Shoot system

StemInternodeNodeTerminal budsAxillary buds

LeavesPetioleBlade

Shoot apical meristemLeaf primordiaAxillary budsApical meristem

Eudicot stem cross section: Epidermis

CortexPith

Vascular bundle Xylem Phloem

Eudicot leaf cross section Cuticle

Upper epidermisPalisade parenchyma

Spongy parenchymaMesophyll

Air spacesVascular bundle

Xylem Phloem

Lower epidermis Stomata Guard cells

Clean up procedures for this lab:

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Put everything back in its proper place. If you made wet mounts, dispose of the slides and glass coverslips in the broken glass container. Plastic coverslips may be discarded in the trash.

Lab 10: Fungi

I. Brief Background

Fungi are an ancient monophyletic group of enormous ecological and social importance. All good biologists are keenly aware of them. Fungi have vastly different life styles from animals and plants.

Some Texas connections:http://www.texasmushroomfestival.com/ http://cahe.nmsu.edu/news/1997/052997_sorghum_ergot.html You can also search Wikipedia for ergotism.



III. Student Tasks

Task 1: Fungi Examine the specimens and slides. Identify the structures.

Phylum Zygomycota: Rhizopus Hypha (hyphae)SporangiophoreSporangium (sporangia)Asexual spores GametangiaZygosporangium (= zygospore)Suspensor cells

Phylum Ascomycota: PezizaHypha (hyphae)AscusAscocarpAscospores

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http://cahe.nmsu.edu/news/1997/052997_sorghum_ergot.html

http://www.texasmushroomfestival.com/


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Phylum Basidiomycota: Coprinus and Agaricus Hypha (hyphae)Basidiocarp (= tertiary mycelium)PileusStipeGillsBasidium (basidia)BasidiosporesSecondary mycelium

Task 2: Lichens Examine the specimens and slides. Identify the structures.

LichensGrowth forms: crustose, foliose, fruticoseAscocarps

Lichen Thallus slideFungal hyphaeAlgal cells

Task 3: Endomycorrhizae (Phylum Glomerulomycota) Examine the slides. Identify the structures.

Endotrophic mycorrhizae slideHyphaePlant root cells with fungusPlant root cells without fungus

Clean up procedures for this lab: Put everything back in its proper place. If you made wet mounts, dispose

of the slides and glass coverslips in the broken glass container. Plastic coverslips may be discarded in the trash. If you dissect anything in this lab, clean up the tools and dissecting tray. Dissected parts can be thrown away in the regular trash.

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Lab 11: Sponges, Cnidarians and Platyhelminths

I. Brief Background

Scypha (also known as Grantia) is used here as a representative of the sponges. There are also a variety of sponge specimens available to show the gross anatomy of sponges. Students should know general characteristics of this phylum and additional examples of organisms in it. There are a few freshwater sponges but most are marine. Sponges are sessile animals. As adults they filter feed, pulling water in through numerous small holes (pores or ostia) on their surface and filtering out microscopic organisms before shooting the water out of larger holes (oscula) on top of their bodies.

More information about sponges, especially weird carnivorous sponges, can be found at: http://www.ucmp.berkeley.edu/porifera/poriferalh.html

Hydra and Obelia are used here as representatives of the phylum

Cnidaria. Students should know general characteristics of this phylum and additional examples of organisms in it. Hydra lives in fresh water while most cnidarians are marine. Obelia is a marine cnidarian that is often used to demonstrate the typical life cycle of cnidarians and the two basic body forms found in this phylum. It alternates between sexual medusae and asexual polyps during its life cycle.

Briefly visit these sites for some Texas cnidarians. http://www.tmc.edu/health_briefs/05_01_98-sting.html http://en.wikipedia.org/wiki/Craspedacusta_sowerbyi (Craspedacusta occurs in

Travis County.)http://flowergarden.noaa.gov/image_library/images_maps_figures/gulf_map.jpg http://www.gulfbase.org/reef/view.php?rid=fgb1 http://www.tpwd.state.tx.us/learning/webcasts/gulf/jellyfish.phtml

Dugesia is used here as a representative of phylum Platyhelminthes. Students should know general characteristics of this phylum and additional examples of organisms in it. Many free-living members of Platyhelminthes are known by the common name “planarians”. Many other Platyhelminthes are parasitic, tapeworms and flukes for example, and have significant impact on humans and our agricultural animals. Most platyhelminths are aquatic, but a few are terrestrial.

Briefly consider these “Texas connections” for platyhelminths: http://creatures.ifas.ufl.edu/misc/land_planarians.htm (Bipalium is fairly common in Austin) and http://www.dshs.state.tx.us/idcu/disease/taeniasis/faqs/.

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http://www.dshs.state.tx.us/idcu/disease/taeniasis/faqs/

http://creatures.ifas.ufl.edu/misc/land_planarians.htm

http://www.tpwd.state.tx.us/learning/webcasts/gulf/jellyfish.phtml

http://www.gulfbase.org/reef/view.php?rid=fgb1

http://flowergarden.noaa.gov/image_library/images_maps_figures/gulf_map.jpg

http://en.wikipedia.org/wiki/Craspedacusta_sowerbyi

http://www.tmc.edu/health_briefs/05_01_98-sting.html

http://www.ucmp.berkeley.edu/porifera/poriferalh.html




III. Student TasksTask 1: Sponges

Examine the sponge specimens and slides of Scypha (Grantia). Identify the structures.

Entire sponges:Ostium (ostia)Osculum

Slides:ostium (ostia)incurrent canalradial canalspongocoelchoanocytes

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Task 2: Cnidarians – Hydra Examine living specimens and slides of Hydra. Identify the structures.

Type of symmetry Gastrovascular cavity Mouth Hypostome Tentacles

CnidocytesBasal disc (“pedal disc”)BudGonadsEpidermis GastrodermisMesoglea

Feeding Hydra: Place a healthy Hydra in a watch glass or depression slide with some food (Daphnia). Choose a small live Daphnia or you may see a defensive response, not a feeding response. Feeding response can be slow—so patience is required.

Task 3: Cnidarians – Obelia, a colonial hydroid Examine prepared slides of Obelia: hydroid colony and medusae. Locate

the structures.

Feeding polypsTentacles

Reproductive polypsMedusa buds

Mature medusaTentaclesMouth

Task 3: Platyhelminths Examine living specimens of Dugesia in watch glasses and observe their

behavior. Examine slides (whole mounts, x-sec). Identify the structures.

Type of symmetry Dorsal surface Ventral surface Anterior end

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Posterior end Left side Right side Cephalization

HeadAuriclesEyespots (eyecups)MouthPharynxEpidermisGastrodermisMesenchymeGastrovascular cavity

Clean up procedures for lab:Return the living specimens to their appropriate culture jars. Return

prepared slides to the correct boxes.

Watch glasses and depression slides are not disposable. They should be cleaned, dried and saved for future use.

If you made wet mounts on a regular slide, dispose of the slides and glass coverslips in the broken glass container. Plastic coverslips may be discarded in the trash.

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Lab 12: Mollusks and Annelids

I. Brief Background

Loligo is used here as a representative of the phylum Mollusca. The mollusks are a varied and successful group of invertebrates. Most mollusks are marine, but there are also lots of freshwater and terrestrial species. While most mollusks have external shells, most cephalopods do not. Cephalopods are cephalopods are predatory and their external features reflect this lifestyle. You can find more information about squid mating displays (including color changes and behavior) at: http://www.nhm.ac.uk/hosted_sites/tcp/Ssepioidea.html

Lumbricus is used here as a representative of the phylum Annelida. Students should know general characteristics of this phylum and additional examples of organisms in it. It is a well-known annelid, familiar to gardeners and fishermen; it is inexpensive and easily reared or procured at bait stores. It is atypical of its phylum in that it is terrestrial --most annelids are aquatic. Earthworms provide a good introduction to metamerism.

Briefly consider this “Texas connections” for annelids. http://digital.library.unt.edu/permalink/meta-dc-5476 (proteomics)http://www.sbs.utexas.edu/shankland/default.htmhttp://flowergarden.noaa.gov/image_library/video/christmastreespawning.mov

(Aquatic annelids off Texas' coast)



III. Student Tasks

Safety Notes:1. Use nitrile gloves and wear safety eyewear while dissecting specimens.2. Dispose of gloves and all preserved specimen scraps in the scrap bucket.3. Fresh specimens (not preserved) should be put into a bag and placed in the

regular trash.4. Fluids from preserved specimens should go into the appropriate container.5. Disinfect tables after completing the dissection.6. Wash your hands before you leave the room.

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http://flowergarden.noaa.gov/image_library/video/christmastreespawning.mov

http://www.sbs.utexas.edu/shankland/default.htm

http://digital.library.unt.edu/permalink/meta-dc-5476

http://www.nhm.ac.uk/hosted_sites/tcp/Ssepioidea.html


Task 1: Mollusks – Squid AnatomyExamine the external anatomy of a squid and identify the structures.

HeadBodyMantleFinsEyesArmsTentacles with tentacular clubsFunnelMouthBeaks

Remove the beaks with forceps. Notice how the ventral beak overlaps the dorsal beak, just opposite to a parrot's beak. Make small cuts in the edge of the mouth, so you can open it to extract the radula. Remove the radula with forceps. Put the radula and beaks into a small dish with water and examine with the dissecting microscope.

Put the squid on its back and open the mantle along the midline. Locate the gills and the pen. The pen is what remains of the shell.

Task 2: Annelids – Earthworm Dissection

Obtain a living earthworm and observe its external anatomy. Type of symmetry Anterior endPosterior endDorsal surfaceVentral surfaceAnnulus (Annuli)Clitellum ProstomiumMouthAnus

Brush a fingertip along the side of the worm from back to front to feel the setae. Observe the behavior of the earthworm.

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Place your earthworm into the 50% ethanol solution. (Check with your instructor before you do this.) This solution will anesthetize it quickly. Wait until the earthworm stops squirming, about 10-15 minutes.

Pin the earthworm to the dissecting tray bottom, dorsal side up and 5-7 cm from the side of the tray. One pin goes through the prostomium. Another pin goes 7-10 cm posterior to the clitellum.

Use a scalpel to make an initial cut through the dorsal body wall, posterior to the clitellum. Then use fine scissors to cut forward to the prostomium along the dorsal midline. Be careful to cut only through the body wall. Do not cut into internal organs underneath. It helps to keep the blades of the scissors parallel to the bottom of the dissecting tray.

Spread out the body wall and pin it to the dissecting tray so you can see internal organs. Use a dissecting probe to break the septa as you do this. Add water to prevent the organs from drying out while you observe the critter's innards. You'll need a dissecting microscope to find the small stuff, like the brain.

Identify the structures:Septum (Septa) Segment Coelomic cavity (coelom) PharynxEsophagusCropGizzardIntestineSeminal vesiclesSeminal receptaclesDorsal blood vesselVentral blood vesselAortic arches (hearts)Metanephridia

Remove part of the intestine and locate the ventral nerve cord.

To see the cerebral ganglia (brain), open the dorsal wall through the prostomium. Look for two white structures.

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Obtain an earthworm cross-section slide. Locate these structures.

Lumen of intestineTyphlosoleCoelomic cavity (coelom) Metanephridia Setae (if visible)

Clean up procedures for this lab: Put everything back in its proper place. Dispose of gloves and preserved

specimen scraps in the scrap bucket. Fresh specimens (not preserved) should be put into a bag and placed in the regular trash. Fluids from preserved specimens should go into the appropriate container.

All dissecting equipment, including pins, must be washed and dried before stowing. Clean off your desks with Lysol or appropriate cleaning solution. Wash your hands before you leave the lab room.

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Lab 13: Arthropods

I. Brief Background

Homarus is used here as a representative of the phylum Arthropoda. Students should know general characteristics of this phylum and additional examples of organisms in it. Homarus is a well-known arthropod, famous as a food for humans. It is useful as a representative of Arthropoda for beginners because it is large and easy to examine. (Crayfish can be substituted, but are much smaller.) This is also an excellent example for illustrating biological homology (lobster appendages are mutually homologous) and metamerism.

Briefly consider these sites for lobster relatives in Texas. http://www.tpwd.state.tx.us/publications/annual/fish/crabreg/ http://www.tpwd.state.tx.us/learning/webcasts/gulf/coastal_bays.phtml



III. Student Tasks



Task 1: External Anatomy of LobstersExamine the external anatomy of the lobster. Determine whether your

specimen is a male or a female. Identify the structures.

Frozen lobsters should be submerged in warm water in lab sink immediately prior to dissection.

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http://www.tpwd.state.tx.us/learning/webcasts/gulf/coastal_bays.phtml

http://www.tpwd.state.tx.us/publications/annual/fish/crabreg/


Verify the general body regions and surface features.

Type of symmetryCephalothorax AbdomenRostrumCompound Eye CarapaceTelson Anus

Examination of the appendages should begin at the posterior end from a ventral view. From ONE SIDE ONLY, remove appendages one at a time (be sure to take entire appendage), discuss their functions, set them aside for photography and sketching. When you reach the rear-most walking leg a fresh challenge arises; important portions of appendages are hidden under the carapace. These hidden structures (are they internal or external?) need to be removed along with the “leg” to which they are attached.

When you reach the large pincers you are only a little more than half finished with appendages. Continue careful appendage removal until you reveal the mouth (surprisingly difficult to perceive, although it is quite visible). You will return to the mouth when you are engaged in internal anatomy examination.

Antennules (= First Antennae)Antenna (Antennae)Maxilla (Maxillae)MaxillipedsChelipeds (chela, chelae)Walking legsGillsSwimmeretsUropods

Task 2: Internal Anatomy of LobstersFor internal anatomy, turn your animal with its dorsal side up and work to

remove one side of its carapace (same side as appendages were removed). This should be sort of like shelling a hard-boiled egg—there is a distinct membrane below exoskeleton. Leave it intact if you can—it will need to be removed, but if it remains intact while removing half the carapace, you will be assured that the delicate heart will be intact. The heart, like the mouth, can be difficult to perceive, even though it is large. Look for its ostia as a visual cue.

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Students often confuse the following structures: gonads, digestive gland, antennal gland (green gland). Here are some pointers:

Digestive gland is usually largest, most conspicuous internal structure and is usually a yellowish green.

Antennal gland (green gland) is entirely different—it is at base of antenna and it is a dark green;

Gonads, both ovaries and testes, also are often green (ranging from blackish to yellowish) green—they are highly variable in appearance depending upon reproductive status of animal—but generally parallel the intestine for much of its length.

While examining digestive system, be sure to put a dull probe into the mouth and discern the mouth’s relationship to the stomach. Open the stomach and carefully examine its interior; you will likely see its last “meal” but you also should see some complex structures comprising the stomach’s walls. What can you hypothesize about their function? Of what material do they appear to be composed?

Abdominal segments are largely muscle, but be sure to examine the easily visible intestine (locating anus will help) and nerve (visible through exoskeleton). Make special note of spatial relationship between nerve and intestine.

HeartOstia

StomachGastic mill

Ovaries, testesAntennal gland (= green gland) Nerve cord Brain




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Lab 14: Chordates

I. Brief Background

Rattus norvegicus (domestic rat) are used here as representatives of the phylum Chordata. Students should know general characteristics of this phylum and additional examples of organisms in it. Furthermore, biologists working in research areas associated with human health care (including pharmacy) can expect extensive use of rats in professional research.

Wild rats are traditionally viewed as a nuisance. For example:http://www.plano.gov/Departments/Health/rat_control.htm

There is good reason: http://www.cdc.gov/mmwr/preview/mmwrhtml/00001270.htm



III. Student Tasks



Task 1: Rat Dissection Examine the external anatomy of a preserved rat and identify the general

body regions:Head: pinna (external ears), eyes, whiskers, mouth,Body

Thoracic regionAbdominal Region

TailForelimbsHindlimbs

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http://www.cdc.gov/mmwr/preview/mmwrhtml/00001270.htm

http://www.plano.gov/Departments/Health/rat_control.htm


ClawsHairNipples of mammary glands

Working from a ventral view, open a window in the integumentary system with a mid-ventral cut from lower abdomen to upper thoracic region. Follow with three cuts at right angles to the first—one cut in lower abdomen another cut in at bottom of rib cage and another above the heart region. Skin should lie away from intact musculature below.

Open abdominal cavity and examine it thoroughly. Early on, identify the caecum and avoid opening it. Identify the large liver. Later in abdominal examination, it will be necessary to remove the liver in order to examine structures behind it.

Examine diaphragm and esophagus’ connection to stomach before opening thorax. Cutting through ribs will now open the thoracic cavity. Examine it thoroughly. Observe the heart and lungs.

Proceed to neck and head. It will be necessary to make a difficult cut through the hinge of jaw in order to lay open the pharynx.

Use the rat skeleton to observe the skull and other parts of the skeletal system.

Integumentary systemSkeletal system (observe on rat skeleton)

Axial divisionAppendicular division

Muscular systemDiaphragm

Digestive systemMouthHard palateSoft palateSalivary glandsPharynxEsophagusStomachSmall intestine (duodenum), mesenteryCaecumLarge intestineRectumAnusLiverPancreas

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Circulatory systemHeartSpleen

Gas exchange (“respiratory”) systemPharynxLungsTracheaLarynx

Urinary systemKidneyUreterUrinary bladderUrethra

Nervous systemEye

Endocrine systemAdrenal glandThymusPancreas

Reproductive systemTestesScrotumVas deferensOvariesUterusOviduct (cp. Fallopian tube)




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Lab 15: Chemical Signals

I. Brief Background

Chemical signaling is very important in living organisms. It allows organisms to sense chemicals in their environment and to communicate with one another. It also allows cells within a multicellular organism to communicate, so they can coordinate their activities. Chemical signaling underlies organ system physiology and development. You can read more about cell communication within multicellular organisms in Chapter 11. Chemical signaling in plants is in Chapter 39. Chemical signaling in animals is in Chapter 45.

II. Pre lab assignment


III. Student Tasks

Task 1: Alcon Blue Butterfly Video Watch the Attenborough video about Alcon Blue butterflies, gentian plants,

ants and ichneumon wasps. The video will be shown by the instructor. Here is the web site: http://www.youtube.com/watch?v=Mb3OQPT3qbU

Discuss the video with your group and answer the following questions.

1. Flow chart the life cycle of the Alcon Blue butterfly.

2. Flow chart the life cycle of the ichneumon wasp.

3. Discuss the roles of chemical signals seen in this video.

4. Discuss the four types of intra- and interspecific interactions seen in this video.

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http://www.youtube.com/watch?v=Mb3OQPT3qbU


Task 2: Termite Tracking

Obtain the following materials:Petri dish White paper Pens of different colors and types Pencils of different colorsScissorsTermites

1. Cut a piece of paper to fit the inside of your petri dish.

2. Draw a large figure eight on the paper with a ballpoint pen. Go over the figure 8 carefully several times with the pen. Place the paper in the petri dish.

Note: the ink needs to be fresh. Do not try to be efficient and make all of your figure eights in advance.

3. Coax a termite onto a scrap piece of paper which can be used then to place the termite onto the paper in your petri dish. Observe its behavior when it encounters the figure 8.

4. Record your data in a data chart. Use the following symbols:Tracking response) + No response) –

5. Repeat steps 1-4 using all of the different writing utensils. You will have to change termites after a few minutes, as they get dehydrated and tired.

6. Pool your data with the other groups. Analyze the data and present your conclusions in your posting.

Clean up procedures for this lab: Put everything back in its proper place. Put all termites back into their

original containers. Paper can be discarded in the trash.

Clean off your desks with Lysol or appropriate cleaning solution.

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Lab 16: Electrical Signals and Nervous Systems

I. Brief Background

Although the complexity of different parts of the nervous system varies among vertebrates, the components and organization are essentially the same. The basic functional unit is the neuron, which is supported by a variety of different glial cells. Neurons are linked together to form pathways, which vary in complexity. This lab will focus on examining neurons, a simple pathway, and the basic structure and organization of the vertebrate central nervous system.

II. Pre lab assignment

Examine the diagram on page 1066 of your textbook, which shows the vertebrate nervous system. Identify the brain, spinal cord, and nerves on the shark nervous system diagram (dorsal view). Which components belong to the central nervous system? Which components belong to the peripheral nervous system?


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III. Student Tasks

Task 1: Neurons and Supporting Cells Examine a motor neuron slide using low power of your compound

microscope.

Identify these structures: Neurons

NucleiProjections (axon and dendrites)

Supporting cells

Task 2: Spinal Cord Model Examine a human spinal cord model that shows the spinal cord in cross-

section.

Identify these structures: Ventral median fissure Dorsal median sulcus Gray matter White matter Gray commissure Central canal Ventral horn Lateral horn Dorsal horn Ventral white columns Lateral white columns Dorsal white columns Dorsal root Dorsal root ganglion Ventral root.

Note the position of the spinal cord with reference to the vertebra.

Note how the nerves attach to the spinal cord.

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Task 3: Spinal Cord SlideExamine a cross section of a spinal cord slide, using scanning or low power.

Identify these structures: Ventral median fissure Dorsal median sulcus Gray commissure Ventral gray horn Lateral gray horn Dorsal gray horn Ventral white columns Lateral white columns Dorsal white columns

Task 4: Spinal Reflex – The Patellar Reflex Check the knee-jerk or patellar reflex of your lab partner. Record the

responses of both participants and include in your posting.

1. The subject should sit on the lab table or tall lab chairs with legs hanging over the edge but not touching the floor.

2. Find the patellar tendon of the subject. It is the tendon directly below the patella or knee cap.

3. Strike the patellar tendon with the small end of the reflex hammer and note the response in your lab report. WARNING: Stand to one side or you may be sorry!

4. Divert the subject's attention by having him or her lock hands together and push them together hard while you strike the patellar tendon again. Note the response.

5. Change places and have your lab partner test your patellar reflexes.

6. Compare the results with your class mates.

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Task 5: Comparative Brains Examine the brain models of various vertebrates:

Lamprey larvaDogfish sharkTroutFrogAlligatorPigeonRabbitDog or Human

Locate these structures: Cerebrum Cerebellum Brain stem (medulla + pons + midbrain) Optic lobes (except human) = superior colliculi of midbrain Olfactory bulbs Pituitary gland Spinal cord

Color Coding on the Models:Yellow = cerebrum, olfactory lobesBlue = optic lobesGold = hypothalamus and pituitarySalmon = cerebellumWhite = brain stem and spinal cord

Observe the differences between the various brains, especially the relative size of the various parts and how much folding is visible on the surface.

Estimate the relative percentages of each structure.

Fill in the tables on the next page.

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For each vertebrate, estimate the percentage of total brain mass taken up by these brain regions: (Note: will not add to 100%)

Vertebrate Cerebrum Cerebellum Brain StemLamprey larvaDogfish SharkTroutFrogAlligatorPigeon RabbitDog

Rate the level of folding of the surfaces of the cerebrum and cerebellum in each vertebrate brain. Use descriptive terms such as: high, low, none

Vertebrate Cerebrum Cerebellum

Lamprey larva

Dogfish shark

Trout

Frog

Alligator

Pigeon

Rabbit

Dog

Note: Lobes are not folds.

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Task 6: Sheep Brain Dissection



Obtain a sheep brain specimen in a dissecting tray.

1. Note the meninges, or protective coverings of the brain, if present.

2. Remove the meninges with scissors.

3. Identify these external features: Cerebrum Right and left cerebral hemispheres Longitudinal fissure (separates right & left cerebral hemispheres) Cerebellum Optic chiasma Hypothalamus Midbrain Pons Medulla oblongata Olfactory bulb Spinal cord

4. Use a scalpel to section the brain through the longitudinal fissure.

5. Identify these internal features: Corpus callosum Thalamus Pineal body Hypothalamus Midbrain Pons Medulla oblongata Cerebellum Cerebrum.

Clean up procedures for this lab:

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Put everything back in its proper place. Dispose of gloves and preserved specimen scraps in the scrap bucket. Fresh specimens (not preserved) should be put into a bag and placed in the regular trash. Fluids from preserved specimens should go into the appropriate container.


Check Your Understanding

Identify the structures on the neuron diagrams below. Color each part.

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1. ___________________________ 6. __________________________

2. ___________________________ 7. __________________________

3. ___________________________ 8. __________________________

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1

2

3

4

5

6

7

8

9


4. ___________________________ 9. __________________________

5. ___________________________

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Label the diagram of a spinal reflex arc.

1. ___________________________

2. ___________________________

3. ___________________________

4. ___________________________

5. ___________________________

6. Add colored arrows to the diagram above showing the direction of information flow during a spinal reflex.

Identify these structures on the diagram of a patellar reflex:

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1 2

3

4

5


sensory neuronmotor neuronsensory receptor (stretch receptor)effector (muscle)

Add colored arrows to show the direction of signals.

1. ___________________________

2. ___________________________

3. ___________________________

4. ___________________________

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1

2

3

4


Appendix 1 Illustrating Biological Material

Biologists make frequent use of both sketches and photographs. In this course, you should develop competence at both.

Sketches have the following advantages: They show features that photos do not show—for example, structures’ three dimensional features revealed by repeatedly using fine focus, or subtle differences in color. They can reflect examination of multiple individuals and thus be a sort of composite. They force biologists to look carefully at material, deciding what is important and what is trivial-- thus they document what the biologist perceives at the time of the observation.

Photographs have the following advantages: They are quickly and easily made. They accurately portray shapes, sizes and positions of photographable structures (although only in two dimensions). They record information that is present in the view but not considered important at the time of photo.

All illustrations in this course must include all the following information: identity of material as best it is known, source of material, date illustration was made, person responsible for making illustration, indication of size of material and conditions under which it was viewed.

Sketches are usually made in pencil and are the one place in laboratory records where erasures are not viewed as attempts to hide information. General appearance of sketches is improved if they are enclosed in a circle (for material viewed through a microscope) or a rectangle (for material viewed with naked eye or simple magnifying glass). Leader lines for labels should be at ninety or 45-degree angles and labels should be outside illustration and square with page.

Here is a highly recommended discussion of an unfortunate side of biological illustrations:

http://www.nature.com/ncb/journal/v8/n2/full/ncb0206-101.html.

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http://www.nature.com/ncb/journal/v8/n2/full/ncb0206-101.html


Here is an example of a mediocre sketch and a mediocre photograph of the same material. Sketches reveal what a biologist deems important at the time of drawing (notice red-stained structures are ignored in sketch) and include interpretations of material (note indications of haploid and diploid and reference to missing structure). Photos, on the other hand, show everything equally—crucial cells are equal to dust on the slide as far as a photo is concerned.

Drawings and photographs are data, not works in progress. Changes made later (label change, inversion of photo, etc) should be treated as corrections to data—as you would treat a correction in a table of quantitative data.

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Note here that changes have been made and notated in lower left corner.

Carefully prepared biological drawings (as for publications) often contain large amounts of implied information. They illustrate the way things are “supposed” to look—and thus the way we are “supposed” to perceive them; they often imply relationships among juxtaposed drawings; they often summarize, in visual terms, theoretical predispositions of the artist. This famous illustration by

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Ernst Haeckel shows some hard-to-see bones as they are supposed to look and implies homology among them.

(Haeckel is famous for contributing to our notion of biological homology. Students might be interested in investigating “Haeckel’s Law”. One site for it: http://www.bookrags.com/research/haeckels-law-of-recapitulation-ansc-03/)

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http://www.bookrags.com/research/haeckels-law-of-recapitulation-ansc-03/


Appendix 2 Maintaining Laboratory Notebooks and Related Records

Doing science, like performing art, is often a self-conscious activity drawing on personal discipline and cultivated practice. Consciously “doing science” requires an important habitual discipline of creating records. This habit usually must be learned (rarely does it come naturally), but scientists value it greatly; it is a large component of our intellectual strength and one of civilization’s greatest benefits.

Our records include, foremost, our observations—“facts” that are not much subject to argument. But our records also include a sort of window on our thoughts—calculations and predictions and labels—that often are subject to reconsideration. All these things are recorded in expectation that they will be examined again in the future, at a time when the immediacy of the present is forgotten or unknown.

How much information should be recorded? Well certainly one should record everything that seems pertinent, but one never knows what seemingly trivial fact will be important in future considerations. While filtering, it might seem completely adequate to say “solution was filtered” but some day it might be useful to know what brand of filter paper was used. When scientists are repeatedly using equipment, microscopes for example, they should record equipment particulars in a separate place in their notebooks (near front or near back).

Biologists have long established practices of “vouchers”—actual specimens of living things—that are preserved as records. These can be pressed and dried plants, frozen samples of blood, pelts of animals, etc. This practice (dating from at least the 18th century) has served us well especially now that protein and DNA analysis can add new dimensions to our observations. As much as is practical, students should retain actual samples of their studied organisms. Obvious exceptions exist: items that are likely to decay and stink, items that are large, items that are hazardous, etc.

Our current age of electronic records and communication gives scientists new opportunities for collection, manipulation, dispersal and examination of records. In this course, students are expected to utilize both traditional written-on-paper records and electronic ones.

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Appendix 3: Using “Prepared” Slides

Take one slide at a time; they must be shared and we don’t have one for each student. Share these slides.

Slides are not equally good. Have some idea about what you need to see before grabbing the first available slide; read the label on the slide (not just the label on the box); boxes often have several different subjects housed inside; often slides are filed in a wrong box. Some companies produce consistently better slides than others. With your illustration, name the company that produced the slide. Generally you should seek slides that show typical features of your subject. It usually is a waste of time to concentrate on aspects of a slide that are accidents of its preparation (artifacts, we call them) or that are not illustrating the purpose of the slide.

Take care to replace slides in their correct box when you finish. Never leave slides on the microscope.

Slides get very dirty. Wipe with lens paper or chem wipe.

Here are some standard abbreviations:cs = cross sectionls = longitudinal (long) section wm = whole mount

Preparation of “prepared” slides can be quite complex. Often materials have been fixed, dehydrated, embedded, sectioned, stained, and mounted.

Fixation of tissue is rapid killing and preserving against change. Fixatives are often extremely hazardous and are among the greatest hazards faced by beginning laboratory workers.

Dehydration of tissue is gradual replacement of water in tissue by alcohol—this is needed in order to accomplish the next typical step.

Embedding of tissue is replacement of alcohol (which replaced water) with paraffin (or substitute) which, when hardened, will allow for very thin slicing or sectioning.

Sectioning of tissue is cutting into suitable thin slices (thin enough to transmit light). It usually involves a specialized machine called a microtome.

Staining of tissue usually involves adding coloring agents with some specificity for components of the tissue. Sometimes multiple stains are

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employed. Almost all color in prepared slides results from these stains—prior processing removes most natural color.

Mounting of sections involves careful placement of sections on slides and “gluing” cover slips.

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Appendix 4: Reading a Vernier Scale

(See also http://physicspmb.ukzn.ac.za/OnlineExercises/IntroVernier/intro2.html )

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Main scale--here reading between 10 and 11, about halfway between them.Vernier

scale--here its 6 mark is most closely aligned with a mark on the main scale. This scale is reading 10.6 units.

Main scale--here reading between 6.2 and 6.3, but closer to 6.2.

http://physicspmb.ukzn.ac.za/OnlineExercises/IntroVernier/intro2.html


Appendix 5: Constructing Graphical Displays of Data

Students should already be aware that numerical data often are presented graphically. They should cultivate skills at graphic presentation (especially using excel) but they should also develop discernment regarding appropriate and inappropriate graphic display.

Graph Example 1: Data (these are not real data) presented in a table—at almost every hour, on the hour, the number of birds at a bird feeder was recorded. A few hours were missed.

Hour of Day

Number of birds at Station

1 02 0

3No count made

4No count made

5 06 37 68 119 21

10 111 112 013 014 215 016 017 018 319 520 421 122 023 024 0

A data table is almost always a good first presentation of data. It is the starting point for almost all other graphic presentations. Sometimes it is enough.

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Graph Example 2: Same (fake) data presented in a simple scatter plot—a scatter plot usually contains no information other than that in its table, but may suggest patterns.

Scales must, of course be appropriate to the subject and regular in their intervals. ( For example, here we have “number of birds” not “log number of birds” and “Hour of Day” not “Year of Century”; also every marked interval on the y-axis is 5 birds and every marked interval on the x-axis is 2 hours.)

Scientific data often have a distinct independent (x) variable and a distinct dependent (y) variable. If time is one of the axes, it usually is the independent variable.

A good graph title says something other than re-stating the axes. Axes must always be labeled and usually have units indicated.

A scatter plot is almost always a good second presentation of data.

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Graph Example 3: Same (fake) Data presented in an appropriate bar graph

Bar graphs contain no more information than scatter plots and are subject to the same requirements.

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Graph Example 4: Same (fake) data presented in an inappropriate bar graph

This graph is an example of a practice that students should AVOID. It is displaying three dimensions of “data” when only two exist. That third dimension (easily added by graph drawing programs) should be used only if there is a third dimension of data to show—for example if temperature had been recorded at each hour, we might have an interesting and valid third dimension to graph. But we don’t; this “fluff” is distasteful and actually impedes good interpretation of data.

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Graph Example 5: Same (fake) data with an inappropriate line drawn

Inserting a line into a set of data points should be done thoughtfully. To insert a line implies continuity of variables—here it implies that at hour 7.25, there were (or could have been) 11.3 birds present. This is not reasonable since “number of birds” is a discrete variable—it only exists in whole numbers. (Time, by contrast is a continuous variable—there is such a thing as hour 7.25.)

Furthermore, it is not reasonable to expect this relationship to be linear, even though parts of it may be extremely linear (linear regression can be used to determine what line most nearly is described by a set of points).

Some biological relationships are regular, but not linear. For example, this data set suggests (but does not directly address) a hypothesis that this feeding station experiences two episodes of feeding per day.

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Graph Example 6: Same (fake) data with many inappropriate lines drawn

This graph has the same problems as the previous, except that there are several lines instead of only one.

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Appendix 6: Using “Blackboard”

BIOL 1407 students at Austin Community College are required to utilize “Blackboard” to access most materials for this course.

Students must establish their electronic identification with ACC. This is called an “ACCeID”

From ACC’s homepage (http://www.austincc.edu/) go to lower right corner and select “Blackboard Login”.

Select student guide and login. Explore and see how much you can figure out.

Blackboard is complex and only a few of its features will be utilized in BIOL 1407, so don’t try to comprehend it all at once. Your familiarity will increase with usage.

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http://www.austincc.edu/


Appendix 7: Measuring Area of an Irregular Shape

Biologists frequently need to know an irregular shape’s area. Some variation of the following method often will suffice.

If the object is sufficiently flat, the object or its photograph or a tracing of its outline, is placed under a transparent grid (often graph paper). The number of squares within the outline is then counted or, better, the number of line intersections is counted. This provides a direct measurement of the number of grid units2 that comprise the area of the image. If object is a photograph, grid units2 are then converted to “real world” units2; thus, the real world area of the object is measured.

Smaller spaces on grid result in more accurate measurements of area.

Example: this shape on the left is placed under a grid and the number of intersections counted (for an intersection that falls on the line, count it as a half). In this example, the area of the shape is 209 square grid units.

If we have determined that, in this situation: 9 linear grid units = 25 mm, then (9 linear grid units) 2 = (25 mm) 2 or 81 grid units2 = 625 mm2

The real world area of our shape is: 209 grid unit2 x (625 mm2 / 81 grid units2) = 1613 mm2

Software now exists that does this automatically, if images are digital.

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Appendix 8Using our Spectrophotometers

See also: (http://www.austincc.edu/biology/labmanuals/140612th/12th1406lab02.pdf )

Steps 1—5 require chamber to be empty and closed. Step’s numbers refer to illustration of machine.1. clockwise turns on, counterclockwise turns off2. every time this setting is changed, machine must be re-zeroed3. often overlooked4. switch 5 toggles among various functions, verify transmittance5. set the mode you plan to use—usually absorbance6. understand what a blank is—verify that you are using cuvettes, not test tubes7. set according to function you plan to use (usually A)—NOT knob 48. hash mark forward, no smudges, bottom third of cuvette all that needs to be filled, CLOSE

CHAMBER LID 9. readings should not be taken during the first 3 seconds while machine is settling on reading; as

soon as reading is taken, remove sample and close chamber lid.

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Appendix 9: Interpreting Absorbance Spectra

An absorbance spectrum is a pattern, usually presented as a graph that shows a compound’s relative absorbance of various wavelengths of light. This pattern is almost never a simple geometric curve or line, but rather a series of “peaks and valleys”. Wavelengths that coincide with peaks and valleys are unique for every compound. Height of peak is proportional to concentration of compound.

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absorbance

Wavelength (nm)

Absorbance Spectrum Compound B

absorbance

Wavelength (nm)

Absorbance Spectrum Compound A at lower concentration than previous graph

absorbance

Wavelength (nm)

Absorbance Spectrum Compound A

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