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BIO 102/103 LAB MANUAL APENDICES

CONTENTS

APPENDIX A: USE OF THE COMPOUND MICROSCOPE AND DRAWINGS ................................................................ 2

APPENDIX B: INSTRUCTIONS FOR SUBMITTING SCIENTIFIC DRAWINGS................................................................ 6

APPENDIX C: ORGANIZATION OF DATA .................................................................................................................. 9

APPENDIX D: FORMAL LABORATORY REPORT...................................................................................................... 18

APPENDIX E: FORMAL LAB REPORT MARKING RUBRIC ........................................................................................ 30

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APPENDIX A: USE OF THE COMPOUND MICROSCOPE AND DRAWINGS

BACKGROUND

The microscope is the instrument used in biology to extend the sense of vision to encompass very small

objects. Microscopes were developed during the 17th century and their use revolutionized the way in which

the world was viewed. Biologists discovered that a single drop of water, transparent to the eye, could be

packed with tiny living organisms. In another major discovery, scientists observed that the tissues of all living

things possess a regular, microscopically visible substructure (the units of which came to be called cells).

Biologists today still use fairly unsophisticated microscopes to make observations about living things.

Advances in more sophisticated technology, including scanning and transmission electron microscopes, have

vastly improved our understanding of cell structure and function.

GENERAL CARE OF MICROSCOPES

The compound microscope is a sensitive instrument. It is easily damaged and expensive to repair or replace.

Please handle it with care!

1. To lift or carry a microscope, always grasp the arm of the microscope with one hand while supporting the base of the scope with the other hand.

2. Always set a microscope down on a bench or in its cabinet gently and avoid knocking the eyepieces or other parts against hard surfaces. Rough handling can damage the alignment of the lenses.

3. Always keep the microscope right side up. Many fittings are loosely held in place on the instrument and could fall off and be damaged if the microscope were turned on its side or upside down.

4. Keep the microscope clean. If you spill water or any other fluid on the stage, wipe it up immediately to avoid corrosion of the stage.

5. Use lens paper only to clean lenses. Optical glass is very soft and can be scratched by other types of paper. First, gently blow off loose dust, then gently wipe the lens with clean lens paper. Avoid polishing the lens vigorously.

6. Always look from the side when you rotate the objectives, to make sure that the lens does not hit the slide. A collision could damage the lens, the slide, or both.

7. Always look from the side when you raise the stage, to avoid raising it too high. If the slide hits the lens, both could be damaged.

PARTS OF THE COMPOUND MICROSCOPE

As you read the following description, locate the indicated structures on your microscope.

Microscopes magnify objects through a system of lenses. The compound microscope uses two lenses, so that double magnification takes place:

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i. The ocular lens is located in the eyepiece. Our microscopes have two eyepieces; that is, they are binocular. The ocular lens usually provides ten‐fold magnification. We call this "ten‐power magnification"; it is usually expressed in written form as 10X.

ii. The second series of lenses is composed of the objective lenses, mounted on the revolving nosepiece. Our microscopes have four objectives: a 4X, a 10X, a 40X, and a 100X. Note that the higher the magnification, the longer the lens. These lenses may also be referred to as the "scanning" or low‐power (4X), medium‐power (10X), high‐power (40X), and oil‐immersion lenses.

The total magnification with which you view an object is the product of the magnification provided by the ocular and objective lenses. In other words, if you view a cell using a 10X ocular and a

4X objective, your total magnification is 10 4 = 40X.

The slide to be viewed is placed on the mechanical stage, with the coverslip uppermost. The slide is placed so that the object to be viewed is directly over the round opening in the stage. Metal arms are used to hold the slide in place. The slide is moved by using the adjustment knobs that are located at the side of the stage.

Our microscopes have a built‐in light source located in the base of the scope. The light is turned on and off using the switch on the side of the base; the intensity of the light is controlled using the dial located next to the on‐off switch. The condenser is a system of lenses that concentrates and focuses the light on the specimen. It is located immediately below the stage and is adjusted by a small knob under the stage at one side. Below the condenser is the iris diaphragm; it opens and closes to adjust the amount of light reaching the slide.

At the side of the arm is an adjustment knob for bringing an object on a slide into focus. The large knob is the coarse adjustment. It permits large upward and downward movement of the stage to bring the specimen into the range where it is subject to fine focusing. The smaller knob is the fine adjustment. It permits small upward and downward movement of the stage for final focusing of the image. The innermost narrow ring is a tension adjustment knob, which must be slackened off before using the coarse adjustment. It is tightened when using fine focus to prevent “drift”.

USING THE MICROSCOPE

GETTING SET UP

1. Remove the dust cover.

2. Plug in the microscope and switch on the light source,adjusting it to about 1/3 maximum brightness.

3. Make sure the iris diaphragm is open and raise the condenser until its lens is slightly below the level of the stage.

4. Check the lenses for cleanliness. Clean them if necessary.(Use only lens paper.)

5. Click the low‐power (4X) objective into place. (It should be there already if the microscope was put away properly.)

6. Lower the stage and place a prepared slide on it, with the coverslip uppermost.

7. While looking from the side, use the coarse adjustment knob to raise the stage to its highest position. (Slacken the tension ring first.)

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8. Look into the microscope. Slowly turn the coarse adjustment knob counterclockwise to lower the stage until the object on the slide comes into view. Then use the fine adjustment to bring the object into sharper focus.

9. Whenever you use any binocular microscope for the first time,you should adjust it for your eyes. This allows both eyes to relax and yet each receive a focused image. Therefore it reduces eyestrain. Adjust the ocular lenses to suit your own eyes as follows:

(a) With one hand on each side of the microscope, grasp the plate that holds the eyepieces. Look through the eyepieces and adjust the distance between the ocular lenses to agree with the distance between your eyes, so that the separate fields viewed simultaneously by your two eyes merge into one field.

(b) Note the reading on the scale between the oculars. Set the ring on the right eyepiece to the same reading as noted on the interocular scale.

(c) Close your left eye and use the fine adjustment knob to focus the microscope for your right eye.

(d) Close your right eye and use the ring on the left eyepiece to bring the specimen into sharp focus for the left eye.

(e) View with both eyes. The microscope can now be focused for both eyes by using the normal coarse and fine adjustment knobs.

10. Adjust the focus of the condenser by moving it all the way up and then lowering it slightly.

11. Adjust the amount of light passing through the condenser by closing the iris diaphragm all the way and then opening it as much as necessary while viewing the slide through the microscope. Use only as much light as is necessary to show maximum detail. If you use too much light you will miss fine details in the specimen. The iris diaphragm should be adjusted for every slide and every magnification. You can also vary the intensity of the light by using the dial beside the on‐off switch.

12. After you have focused your specimen using low power and made all the necessary adjustments, you may increase the magnification. Do not use the oil‐immersion (100X) lens unless instructed to do so.

13. Look from the side and rotate the medium‐power (10X) objective into place.

14. Look through the microscope and adjust the focus. You should only need to use the fine adjustment knob. Adjust the light.

15. Look from the side and rotate the high‐power (40X) objective into place. Once again, adjust the focus and adjust the light. You must only use the fine focus adjustment when viewing a slide under high power. Why? Gently tighten the tension ring to prevent drift. If you lose the focus, go back to low power to refocus, then return to high power.

16. After you have finished viewing the slide, lower the stage completely and rotate the 4X objective into place. Then remove the slide from the stage. Be careful not to hit the slide against the objective lens. Return the slide to the correct box.

VIEWING A SERIES OF SLIDES

Once the microscope is set up, you can view a series of slides with only a few adjustments.

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1. Always lower the stage and rotate the 4X objective into place before removing one slide and placing another on the stage.

2. Focus first with low power, then move to higher magnification. Remember to always look from the side when you rotate the objectives into place.

3. Once you have focused with low power, you should only need to use the fine adjustment knob at higher magnification. Remember, with high power, you must only use fine focus.

4. Remember to adjust the iris diaphragm and light intensity when you change slides and when you change magnification.

PUTTING THE MICROSCOPE AWAY

When you finish with the microscope, be sure to do the following:

1. Rotate the 4X objective into place.

2. Lower the stage completely.

3. Remove the slide from the stage.

4. Clean all lenses, using lens paper only.

5. Unplug the microscope and coil the cord neatly at the base of the scope, securing it with a rubber band if necessary.

6. Replace the plastic microscope cover.

7. Return the microscope to the correct cabinet.

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APPENDIX B: INSTRUCTIONS FOR SUBMITTING SCIENTIFIC DRAWINGS

OUTLINE FOR SCIENTIFIC DRAWINGS

(See Figure A‐1 for example drawing)

1. Drawing should be large, and cover most of the paper.

2. All drawings should be done on unlined bond drawing paper. Do not put two diagrams on one sheet of paper.

3. All drawings should be two‐dimensional line drawings using a sharp drawing pencil. A harder lead (type H ‐ 4H) is useful for initial light outlines and boundaries and for final clean, sharp lines. Standard lead, HB, is usually too soft for drawing. No pens are to be used in drawing.

4. Do not draw fuzzy lines or shade in your drawing.

5. Do not colour your drawing.

6. A drawing should be labelled with a line drawn with a ruler (horizontal lines are preferred) running from the label to the part of the drawing being identified. Do not put arrowheads on the lines. Labels should be typed or printed outside the drawing down one side of the page (see example) in a column.

7. All drawings should include the following information:

(a) identification of what it is you have drawn ‐ use genus or species name where possible

(b) microscope magnification. (Note that in microscope magnifications, the “X” follows the number.) OR drawing magnification.

Drawing magnification = drawing size size of object

The drawing size can be measured directly with a metric ruler. The size of the object can be approximated by comparing the object's size to the size (diameter) of the field of view. The diameter of

the field of view in your compound microscope is 4.5 mm (4 500 m) for low power (40X), 1.8 mm

(1 800m) for medium power (100X) and 0.45 mm (450 m) for high power (400X).

Example:

The drawing of a cell is 3 cm (30 mm) in diameter. Viewing through the microscope (high power), the diameter of the cell is approximately one‐sixth of the field of view.

Therefore, its estimated size is: 1

6 0.45 mm = 0.075 mm

Hence:

drawing magnification = drawing size 30 mm

X400size of object 0.075mm

NOTE:

With drawing magnifications, the "X" comes before the number.

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Protist Cell

Amoeba proteus

FIGURE A‐1. SAMPLE DRAWING OF A SINGLE CELL X520

PLANT TISSUE DRAWINGS

In Laboratory 5, you are not expected to spend a lot of time making overly detailed drawings of each section.

The emphasis is on producing a large, clear, pencilled drawing of the section, illustrating major structures

rather than individual cells. Indicate bands and zones of tissue. An example is shown in Figure A‐2. Note

titles, columned labels, horizontal lines and drawing magnification.

Buttercup Stem c.s.

Ranunculus sp.

epithelium

xylem

phloem

cortex

pith

X 45

FIGURE A‐2. EXAMPLE DRAWING OF A DICOT STEM

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CALCULATION OF THE DRAWING MAGNIFICATION (DM)

1. DM = diameter of the drawing . actual diameter of the section.

2. The diameter of the drawing is easily measured. It’s 67 mm

3. The actual diameter of the section is estimated from knowing the diameter of the field of view of the microscope at that particular magnification. For example:

At low power (40X), the field of view is 4.5 mm

We estimate the actual size as 1.5 mm so

4. DM = 67 mm (Same units for both dimensions) 1.5 mm = X45 (Place the X before the # for drawing magnifications.)

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APPENDIX C: ORGANIZATION OF DATA

BACKGROUND

There are two common methods of presenting quantitative data. One method is in a table, which contains a summarized presentation of the numbers themselves, while the other is a pictorial form consisting of graphs, diagrams, etc.

TABULAR REPRESENTATION

Tables are used to present summary results and they are useful for displaying the data for each dependent variable. Below are guidelines to assist in your design of a data table:

1. All values of the same kind should read down the column, not across a row. For example, the number of replicates in each treatment should be listed down a column (Table 1.1). Include only data that are important in presenting the results and further discussion.

2. Information and results that are not essential (for example – test-tube number, simple calculations) should be omitted.

3. The headings of each column should include units of measurement, if appropriate.

4. Tables are numbered consecutively throughout a lab report.

5. The title, which is located at the top of the table, should be clear and concise, with enough information to allow the table to be understood apart from the text. Capitalize only the first word in the title and place a period at the end.

6. Refer to each table in the written text of the laboratory report and summarize the information contained in the table.

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Below is a template for a data table:

Table 1.1: Title goes here, such as: The effect of the independent variable on the rate of the dependent variable in species x.

Treatment

Replicates (n)

Dependent Variable 1 (unit of measure)

Dependent Variable 2 (unit of measure)

Control

Independent Variable

Examples of data tables are presented in Table 1.2 and 1.3.

Table 1.2: Relationship between age and weight in Organism x.

Age (days) Weight (grams)

3 3

4 8

9 6

12 12

18 14

22 19

27 17

31 14

34 20

39 10

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Table 1.3: Change in height and weight of plant species x grown under different nutrient regimes.

Nutrient Conditions Replicates Height (mm)

Weight (grams)

Control (no added nutrients)

25 3 3

N only (5-0-0) 22 4 8

P only (0-5-0) 24 9 6

K only (0-0-5) 25 12 12

N & P 22 18 14

N & K 20 22 19

P & K 19 27 17

N & P & K 24 39 10

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GRAPHIC REPRESENTATION

The results of an experiment usually are presented graphically, showing the relationship between the independent and dependent variable(s). A graph or figure provides a visual summary of the results. Often, characteristics of the data are not apparent in a table but may become clear in a graph. By looking at a graph, then, you can visualize the effect that the independent variable has on the dependent variable and detect trends in your data.

The distance along the x-axis is called abscissa and the distance along the y-axis is called the ordinate. Together such x, y pairs are called co-ordinates. The point where both co-ordinates are zero is called the origin. Figure 1.1 shows these relationships.

Figure 1.1. Principles of plotting graphs and terminology.

The following guidelines will help you to construct such a graph:

1. Use metric graph paper. Use a ruler to draw the axes. The axes should be drawn such that there is room on the page to write a heading for each axis and a title below the graph. Do not draw your axes along borders of the grid; provide room for the axis titles (Figure 1.2).

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Figure 1.2. Change in height of plant species x over time.

2. The independent variable is graphed on the x axis (horizontal axis) and the dependent variable on the y axis (vertical axis).

3. The numerical range for each axis should be appropriate for the data being plotted. Then choose your intervals and range to maximize the use of the graph space. Choose intervals that are logically spaced and therefore allow for easy interpretation of the graph. Generally, begin both axes of the graph at zero. To avoid generating graphs with wasted space, you can break an axis by 2 lines ( || ) between zero and your lowest number on one or both axes.

Pick the best scale in order to fill the graph paper. Note the poor scale choice on the abscissa of Figure 1.3. Only a small portion of the graph paper is actually used to illustrate the graph.

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Figure 1.3. Change in plant height over time (a very poor example).

4. Note the regular increase in value of the scale points on, for example, Figure 1.2. Regardless of the data obtained, the y-axis scale increases in units of 2 cm from 0 cm to 30 cm to cover the data values. Occasionally, a student will attempt to produce a scale in which irregular data is sequenced regularly, e.g., values of 4, 10, 20 and 29 are placed at regular intervals of 10 mm along the axis. This is neat but wrong.

5. Label the axes to indicate the variable and the units of measurement. Insert tick marks on both axes at intervals frequent enough to allow the reader to estimate the value of each data point. Include a legend if colours or symbols are used to indicate different aspects of the experiment.

6. Extend your axes only far enough to cover your data. For example, note that in Figure 1.2, the axes stop at values of 30 cm and 24 days.

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7. Choose the type of graph that best presents your data. Line graphs are suitable for continuous data (it is possible to have a data point anywhere along the axis), whereas bar graphs are suitable for discontinuous data (it is not possible to have a data point between two values labeled on an axis). This is discussed further below.

8. Write the title for your figure below your graph. Graphs, diagrams, drawings, and photographs are all called figures and should be numbered consecutively throughout a lab report. After the number, write a title that describes its content, giving enough information to allow the figure to be self-contained. Capitalize only the first word in a figure title and place a period at the end.

TYPE OF GRAPH

Graphing provides a visual illustration of the results rather than a collection of numbers.

There are three types of graphs commonly used in biology: bar graphs; line graphs and scatter graphs. Each graph is used for a specific type of information. All three types of graphs must have

a clear, descriptive title

clearly labelled X and Y axis with the independent and dependent variables appropriately place.

For a more detailed discussion of graphing, please refer to A short guide to writing about Biology 4th Edition, J.A. Pechenik, 2000. Pearson Education. Pages 172 – 198. This book is available on reserve in your library.

1) Bar graphs – Bar graphs are often used when the independent variable (x axis) is not a number. For example, imagine an experiment where different types of plants are grown under the same conditions and heights are measured after two weeks. The independent variable is the type of plant. The dependent variable is the plant height. Each plant type is represented by a single bar (Figure 1.4).

Figure 1.4. Growth rates of four vegetables over a three week period at 20°C.

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A histogram looks very similar to a bar graph, but is used when we are looking at sorting into classes. For example, if we wanted to assess the weight distribution of a population of scallops, we might sort the scallops into weight classes and count how many individuals were in each class. The X axis would have the weight classes (e.g., 28gm, 30gm, 32gm, etc.). The Y axis would measure how many scallops were in each height class (Figure 1.5). Notice how the bars touch one another whereas they do not in Figure 1.4. This is because Figure 1.5 is representing continuous data, whereas Figure 1.4 is representing discontinuous data.

Figure 1.5. Scallop weight distribution of a sample population.

2) Line graphs – Line graphs are used when the independent variable is measured in numbers and is continuous. These types of graphs are useful to illustrate how a group of organisms responds to a variable over time. For example, you were interested in observing the growth rate of salmon fry raised at two different temperatures and measurements were made every 10 days over a 2 month period. A line graph presents a clear picture of the data. For this example, let’s assume the initial fry length was 7 mm (Figure 1.6).

Figure 1.6. Growth of coho salmon fry (Onchorhyncus kisutch) reared at 5°C and 10°C.

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3) Scatter graphs – Scatter graphs or correlation graphs can be used to see if there is a relationship (correlation) between two variables. They are a way of testing a hypothesis. For this type of graph, any value of X may have more than one value of Y associated with it. For example, you are interested in learning if there is a relationship between the number of leaves on a plant and its height (Figure 1.7).

You chose the following hypothesis before starting the experiment: “The number of leaves increases with increasing plant height.”

For each plant, two measurements would be taken: plant height and number of leaves. Note that you might have two or three plants of the same height but they probably wouldn’t have exactly the same number of leaves.

Plant height is the independent variable, and number of leaves is the dependent variable.

For a scatter graph, we DO NOT CONNECT THE DOTS. Rather, we draw what is called the ‘line of best fit’ through the points.

The closer the points are to this line, the more confidence we have in our hypothesis. The more ‘scatter’ we see, the less confidence we have.

Figure 1.7. Correlation of plant height to number of leaves on salmonberry (Rubus spectabilis).


APPENDIX D: FORMAL LABORATORY REPORT

BACKGROUND

Formal laboratory reports, such as those you will write in this course, are modeled after scientific papers that are published in a peer-reviewed scientific journal. Although different journals require different formats, all papers have a similar format, which reflects the scientific method. Recall that the scientific method consists of making observations, asking a question, formulating a research hypothesis, conducting experiments to test the hypothesis, interpreting the results, and re-evaluation of the hypothesis. These elements are included in a formal laboratory report under the following headings:

Introduction – make observations; ask a question; formulate research hypothesis

Methods – conduct experiments to test research hypothesis

Results – report the outcome of the experiment

Discussion – interpret the results; re-evaluate the hypothesis

Each element of a Formal Laboratory Report is discussed in detail below, using an example of a report written on a study of paper towels. Use the information provided to assist you in writing your own formal laboratory report.

It is STRONGLY RECOMMENDED that students read the following publication:

Pechenik, J.A. 2001. A short guide to writing about biology. 4th Edition. New Yort, Addison-Wesley Educational Publishers, Inc.

There are several copies of this publication on reserve in the college library that can be used on-site. Students can also purchase their own, which would be a wise investment.

The remainder of this discussion is a model report written on a study of paper towels. Notice the clear headings.

TITLE

A brief but descriptive sentence. A recipe might be:

"The Effect of (1) on (2) in (3)" where:

(1) is the manipulated variable of your research hypothesis,

(2) is the responding variable of your research hypothesis

(3) is the system of the research hypothesis.

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Good Title Example:

The Effect of Materials on the Water Absorbency of Paper Towels

Poor Title Example:

Paper Towels and Absorbancy

INTRODUCTION

The purpose of the Introduction is to state any prior knowledge, literature, or observations, and to state your research hypothesis. It is important to put the experiment in context with prior knowledge.

Prior Knowledge

Include references to relevant literature and observations to lead the reader to an understanding of why the experiment was carried out. You should justify why you chose to undertake your study, and you should include definitions of terms and processes that are integral to your study.

Research Hypothesis

State your research hypothesis. After reading your introduction, the reader should know precisely why you came to your hypothesis.

Example

This study was designed to test the hypothesis that water absorbency of paper towels varies with their constituent materials. The media constantly confront the public with advertisements claiming that this or that brand absorbs more water, or absorbs quicker, or is of better value. The commercials suggest that the reasons for differences concern paper thickness, texture or ply.

Objective research studies on paper towel absorbencies are relatively few. Early work by Whyte and McIntosh (1990) found that some, but not all, two-ply towels absorbed more than single-ply brands. In a later study, Whyte and McIntosh (1991) concluded that, regardless of number of plies, the thickness of a towel had a significant effect on its absorbency. In both of those studies, the researchers immersed pieces of paper towel in water to determine their absorbencies. Subsequently, using the same technique, Runkle and Bergunder (1994) determined that texture (“pillows” versus “non-pillows”) could also produce a significant increase in the absorbency of a towel.

A more thorough investigation was performed by Consumer Reports (1999). Using every major brand available, it confirmed the previous studies’ findings regarding plies, thickness and texture but did not investigate paper towel materials. Materials are not consistent across the many brands: some use only new pulp; some only recycled; some a mixture of the two. The effect of recycling on wood pulp has been shown to cause a decrease in its water absorbency (Hodgson 1997).

The research hypothesis of a decrease in towel absorbency due to the use of recycled materials led to the prediction that two brands of different towel materials, with the same number of plies and similar textures and thicknesses, taken randomly from those available, would exhibit a difference in

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absorbency in favour of the towel made from new pulp. The brands used for the study were "Abzorb" (new pulp) and "Hi-Suck" (recycled).

Since absorbency refers to the ability of the towels to take up water, the experiment was designed to test the rate of movement of water through the brands of towel. This was a different method from the paper-immersion method of previous researchers. It was predicted that the “new pulp” towel would absorb water more rapidly than the “recycled” towel.

IMPORTANT – How to Cite Literature

Whenever you are writing a paper or a report, you will be using information that comes from other literature sources as well as your own ideas. The reader must be able to identify the source of ideas or information. If they are not yours, you must tell the reader so. If you present a piece of information or an idea that you got from someone or somewhere else and don't identify the source, you are guilty of PLAGIARISM. This is the most serious intellectual and academic crime you can ever commit.

To avoid being found guilty of such a crime when you are writing, protect yourself by providing the reader with the names, dates and places where you obtained information and ideas.

Before describing the citation technique to be used, a further word about plagiarism is in order. Many students think that they only need to give (= cite) sources when using direct quotations. Not true. Not only must sources be cited with quotations, but sources must be cited even if you have completely re-written the material and placed it in a totally different context. If you fail to cite, you are guilty of fraud: the act of portraying the work of someone else as your own. Acts of plagiarism will not be tolerated.

Any fact, idea or piece of information that comes from a source other than your head (REPEAT - ANY FACT or IDEA), must be followed immediately by an indication of its source. This is a citation. For this course, we are using the conventional author-date system. You should have already noticed its use in the manual.

The following quote comes from a journal article about the feeding ecology of woodland spiders in England (Adams 1984, p. 363).

"The technique used in this study is similar to that described by Pickavance and Smith (1970) and Adams (1981a)."

So, the author-date system can be used basically two ways:

1. If the name of the author is part of the sentence, then the date, in parentheses, follows the name immediately.

2. If the name of the author is not used in the sentence, then both author name and date, in parentheses, follow.

Why the letter ‘a’ after the Adams date (1981a)? Because somewhere in the text, the author has referred to another work by Adams, also published in 1981, and that will be given as Adams (1981b).

If you have used a direct quotation, indicate after the date the page number, i.e., Adams (1981b, p. 44).

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Then what? At the end of your paper/report you will list EACH, ALL and ONLY references that are cited in the text. This is discussed in the section on References later in this appendix. This is not a bibliography; you list only the references you cited.

If you copy material directly from a literature source, this information MUST be surrounded by quotation marks, see above. However, you are advised against using quotations except in extraordinary circumstances. Direct quotes, which must be surrounded by quotation marks and contain a reference to the page number in the citation, should only be used when a statement is profound and cannot be stated in any other way. We are interested in YOUR interpretation and analysis of results. When you find information or ideas relevant to your report (and these will be essential in the introduction and discussion especially), re-write them in your own words so that they are directed to the point(s) you are trying to make.

METHODS

This is where you provide a detailed account of what you did, what form of statistical analysis you used to analyze the data, and state all hypotheses derived from your research hypothesis (HR).

Experimental Design

It must be an accurate and precise series of steps describing all the steps that you took in conducting the experiment, with an explanation of why (if not already given in the Introduction).

Science is based on repeatability of tests of hypotheses. The purpose of this section is to guarantee that possibility. Another researcher must be able to pick up your report and do exactly what you did, and know why you did it. You don't need an equipment list, but all equipment, materials and supplies used should be mentioned in your description.

Imagine that someone has to conduct the experiment, and will be following your methods; if you don't state exactly what you did (or identify another source for that information), your research is not repeatable.

If you had to perform a preliminary study to discover what values to set for manipulated and controlled variables, give them here, and identify the criteria you used in selecting the values for the experiment. Identify all variables that were held constant, and how that was done.

There are some common mistakes which students make when writing this section. To avoid these pitfalls, do the following:

1) Write this section in past tense, passive voice. You have already completed the experiment and you want to explain how it was done.

2) Write this section in paragraph form. DO NOT write in a step-by-step fashion.

Hint: Make extensive notes as you design the experiment, and then make further notes as you conduct it. Don't rely on your memory; it will let you down.

Statistical Analysis

Briefly state the statistical test that was used to analyse the experimental data. Refer to Lab 6 of your manual for the various statistical tests that were introduced to you.

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List all Hypotheses

List all possible hypotheses derived from your HR. This includes your null hypothesis (HO), and all alternate hypotheses (HA).

Example

This study was conducted on two brands of paper towel made of different materials, "Abzorb” and "Hi-Suck". “Abzorb” is made from new pulp whereas “Hi-Suck” is made from only recycled materials. Both towels tested were two-ply, “non-pillowed” and very similar in thickness (within 5%). Ten replicates of equal sizes were allowed to stand in water for a constant time period, water movement was recorded as a rate, and these data were then subjected to statistical analysis to test for a difference in absorbency between paper towels.

Before conducting the experiment, it was necessary to determine the values to set for the size of paper towel used and the amount of water. Although the standard measure of paper towel is the single sheet, some towels have different-sized sheets to others. It was decided, therefore, to standardize on a strip of paper 2 cm wide and 10 cm long. A preliminary estimate of the ability of these strips to absorb water revealed that 100 mL would be more than enough for either brand.

The experiment itself consisted of 10 replicates of “Abzorb” and 10 replicates of “Hi-Suck”, each replicate cut to the standard dimension of 2 cm x 10 cm. From one end of each strip, a line was drawn at 1 cm. For each replicate, 100 mL of water was carefully measured in a graduated cylinder and then poured into a 250 mL beaker. The test strip of paper was attached to a ring clamp by a clothes pin, and then lowered into the water lengthwise, the tip dipping 1 cm below the surface. The time was recorded. After 120 seconds, the level of water was marked on the strip of paper. Throughout the experiment, care was taken to ensure that the temperature of the water remained constant since temperature might influence the rate of water movement through the towels.

The first alternate experimental hypothesis (HA1) stated that "Abzorb" would absorb water faster than "Hi-Suck". The second alternate hypothesis (HA2) stated that “Hi-Suck” would absorb more than “Abzorb”. The null hypothesis (HO) stated that there is no difference in the rates of absorbency of "Abzorb" and "Hi-Suck”.

The distance that the water moved up the paper towel was measured as: (distance from the final mark to the bottom of strip) - 1.0 cm. This was transformed into a rate of water movement per minute. The data on distance moved were then subjected to the Rank-Sum Test.

RESULTS

Outline the results of the experiment. Your results should be presented in the form of tables and figures (diagrams, drawings and graphs). Make certain all axes, rows, columns, numbers are labelled, and make sure the title is clear and descriptive. All figures and tables should have its own number and title. Remember to only include figures that help the reader to understand the results of the experiment. Messy, unclear figures are useless.

Each of the tables and figures should be referred to in the text of the results section. There MUST be written text which directs the reader to the tables and graphs and tells the reader what you want him/her to see. Describe the data.

Remember to provide the results of the statistical analysis and what these results say about your experimental alternate and null hypotheses. If the statistical test says NO DIFFERENCE, then there

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is NO DIFFERENCE regardless of means, averages or what the data looks like. Report the means, critical values and important data or statistics. State whether your HR or HO was supported or rejected.

Example

The results of this study are presented in Table 1, which shows the distance moved by water (in cm) after 2 minutes and the means for the two treatments. This table also shows the data ranked (in parentheses), and the summed ranks for each treatment. Figure 1 presents a bar graph showing the average rate of water movement per minute for the two treatments: "Abzorb" and "Hi-Suck".

There appeared to be slightly more water movement in "Abzorb" towels than in "Hi-Suck" towels. The mean movement of water for "Abzorb" was 2.82 cm, while that for "Scott" was 2.38 cm, a difference of nearly half a centimetre. However, the Rank-Sum Test, with a lowest T value of 70 compared to the critical T value when n1 = n2 = 10 of 78, revealed the probability of these results occurring by chance alone was greater than 5%. The treatments are not significantly different, which caused acceptance of the experimental null hypothesis of no difference between "Abzorb" and "Hi-Suck" towels. While the means were different, variability within treatments as opposed to between treatments was too great to conclude there was a difference in absorbency between “Abzorb" and "Hi-Suck" towels.

Table 1: Distance of water movement (in cm) for 10 replicates of “Abzorb” and “Hi-Suck” towels after 2 minutes, with ranking for the Rank-Sum Test in parentheses.

Replicate Treatment A "Abzorb"

Treatment B "Hi-Suck"

1

2

3

4

5

6

7

8

9

10

2.7 (12.5)

3.1 (16.0)

2.9 (14.5)

1.8 (2.5)

3.2 (17.0)

2.7 (12.5)

1.8 (2.5)

3.3 (18.0)

2.9 (14.5)

3.8 (19.0)

mean = 2.82

Rank Sum = 129.0

1.9 (4.5)

3.9 (20.0)

2.2 (6.5)

2.6 (11.0)

1.9 (4.5)

2.5 (9.5)

2.4 (8.0)

2.5 (9.5)

2.2 (6.5)

1.7 (1.0)

mean = 2.38

Rank Sum = 79.0

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Rate of

Water

Movement

(mm/min)

0.5

1.0

1.5

2.5

2.0

3.0

Abzorb Towels Hi-Suck Towels

Figure 1. Average rate of water movement for 10 replicates of “Abzorb” and “Hi-Suck” towels.

DISCUSSION

This is what the report is really all about. You made some observations and consulted the literature. Then you put that together to come up with your understanding of the system. This pattern or regularity, you hoped, would enable you to make predictions about things you haven't seen. Then you came up with a research hypothesis, a prediction and a test of your understanding. You conducted the test.

So, now what do you think? What do your results tell you about the patterns you thought existed, the way you thought the Universe worked, and the reasons you had for thinking that? The discussion is the place where you consider these questions. There are two possible outcomes from your experiment: your experimental results caused you to accept HO or reject HO. In the discussion, you have to relate your results to HR.

What if your results caused you to accept HO? The first thing to do is work your way back through the experiment to ensure it was done correctly. The kinds of questions you might ask yourself are:

Was the data collected accurately and recorded precisely as possible?

Was the statistical analysis of the data appropriate for the type of data collected and was it done correctly?

Was the experimental design appropriate for the type of question being investigated and were all other variables suitably controlled?

Should there have been more replicates?

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Was the prediction a consequence of the HR?

It is not a bad thing to accept HO. There are a few reasons why you might accept HO:

1. HR is wrong. There really is no affect of the independent variable on the dependent variable.

2. The experiment was not controlled properly and some other variable influenced the outcome of the experiment.

3. The experimental design was not appropriate to test HR.

4. More replicates were needed. It is more difficult to determine if there is a difference between two treatments if you have only 3-5 replicates than if you have 30 replicates.

While it is quite possible that this re-evaluation leads you to see serious flaws in the prediction or the design and conduct of the experiment, as scientists we are a little reticent to dismiss the experiment by admitting "we screwed up." If you have to admit it, you won't lose points so long as you learn from the experience. Make certain you state exactly what you would do to correct the problem. And make a commitment to think a little more carefully next time about your prediction and experimental design and conduct.

Even if you must accept HO, remember that there were good reasons for you to develop your HR in the first place. So, rather than throw it out completely, you may want to consider another way in which to test your HR. The results of this experiment become a new observation to be included in our search for a new understanding of the Universe. The discussion, then, is where you can make proposals for a new or modified HR, and explain why you now think that.

What if your results cause you to reject HO? This, of course, is what you thought would happen, providing it is your expected HA1 that is supported.

However, even if HR supported, again you must re-evaluate the experiment and the prediction to make sure there is no other possible explanation for the results you obtained. In designing your experiment you tried hard to make certain you wouldn't get the right result (accept HA1) for the wrong reasons. However, after conducting the experiment, perhaps you can see problems you didn't see before.

If you are convinced that everything checks out, then you review the reasons for the HR in the first place (these are all given in your Introduction). You should state what it is about your understanding of the Universe that seems to be supported by the experiment. You should also incorporate these results as observations leading to a new understanding, maybe as a more precise explanation of the pattern with suggestions for further research into the problem.

Example

The results of this experiment suggest there is no statistical difference in the rates of water absorbance by "Abzorb" and "Hi-Suck" paper towels. This calls into question the research hypothesis that the use of recycled materials reduces paper towel absorbency. Assuming that the measurement of the distance water moves through the towel constitutes a legitimate measure of absorbency, this result requires modification of the research hypothesis. However, the two brands of different materials used in this study may well have not been sufficiently different in terms of materials that they would exhibit a difference in absorbency. Also, although the two brands used

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were of similar thickness, the slightly greater thickness of the “Hi-Suck” towels may have masked a significantly lower absorbency. (Whyte and McIntosh (1991) have already shown thickness to play a major role in towel absorbency.) Additionally, the fact that the towels were both “non-pillowed” did not mean that their structures were identical. The “Abzorb” towel appeared to be slightly more dimpled appearance than the “Hi-Suck” and this difference in structure may have influenced absorbencies too.

In terms of this experiment, it was noticed that “Abzorb” towels seemed to consume more water than "Hi-Suck" paper towels. Unfortunately, the test was designed to measure the distance that water moved through the paper in a given amount of time (rate of movement) rather than the total amount absorbed. It now seems reasonable to argue that a measure of the exact amount of water consumed by different brands would be a better measure of absorbency, the method used by Whyte and McIntosh (1990 and 1991) and Runkle and Bergunder (1994). One problem, then, may have been in the prediction that differences in absorbency would be reflected in differences in distance of water movement. The two brands of paper towel used may have absorbed different amounts of water even when the distance moved by the water was the same.

REFERENCES

This section is short and contains ALL and ONLY those references cited in your report. It is NOT a bibliography.

Although it is a short section, it is very important that it is done correctly. Please be very careful in the format for listing the references. Use the examples below as a guide and consult the Pechenik guide. Book or journal titles may be either italicized (as shown below) or underlined.

Example

Consumer Reports. 1999. A Comprehensive Comparison of the Absorbencies of Major Brands of Paper Towels. Volume 12 (March 14): 80-87.

Hodgson, C. 1997. Absorbencies of Fresh and Recycled Pulp. Journal of Pulp Technologies 44: 23-30.

Runkle, D and J. Bergunder. 1994. Textures and Absorbencies in Paper Towels. Canadian Journal of Towelology 36: 99 - 106.

Whyte, P. S. and B. McIntosh. 1990. The Influence of Ply Number on Paper Towel Absorbency. Towel Review 42: 361 - 370.

Whyte, P. S. and B. McIntosh. 1991. In Towels: Advances and Opportunities, edited by C. Hodgson. Toronto: Springer-Verlag.

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Your Course Materials

The correct format for citing your Campbell text and lab manual is as follows:

Campbell, N.A. and J.B. Reece, 2005. Biology. 7th ed. Benjamin/Cummings, San Francisco, CA.

Hodgson, C.A., 2007. Laboratory Manual for Biology 103: Principles of Modern Biology. 7th ed. pp. 8-1 - 8-5. North Island College, Courtenay, BC.

Internet References

In general, avoid using Web pages as sources of information. Web pages can be altered frequently and you cannot guarantee their accuracy. Unless you are fully confident of the accuracy of the material presented, please do not use a Web page as an information source.

However, please note that the Web is a very valuable tool to access information from recognized scientific authorities, such as government agencies, major research foundations, or universities. These Web sites are generally recognized as ‘reliable’. Furthermore, you can access peer-reviewed electronic journals that are not available in hard-copy in the library.

If you choose to use a Web site as an information source, you must provide a printout of the Web page with your formal laboratory report and indicate the date accessed. (This is NOT necessary for on-line journals.) Often, the content of Web pages can change from day-to-day and so the information you see on a site might not be available on another day.

To cite a Web page, provide the author's last name and initials (if known) followed by the date of publication. Next, list the full title of the work, capitalizing only the first word and any proper nouns; the title of the complete work or site (if applicable) in italics, again capitalizing only the first word and any proper nouns; any version or file numbers, enclosed in parentheses; the protocol and address, including the path or directories necessary to access the document; and finally the date accessed, enclosed in parentheses.

Example

Burka, L. P., 1993. A hypertext history of multi-user dimensions. MUD history. http://www.utopia.com/talent/ lpb/muddex/essay (2 Aug. 1996).

For further details of WWW references, check out the following web site: http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/Style.html

ABSTRACT

When scientific papers are published the abstract of the paper is often published separately. Therefore, it should be written as a ‘stand alone’ document that provides a summary of the experiment. It is very easy to write, AFTER the remainder of the laboratory report has been written. Therefore, the Abstract should always be written last, but it should be located in a paper immediately after the Title and before the Introduction.

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The Abstract should contain about 5-6 sentences, answering the following 5 questions. You will see below where the answers to these questions will be found in your report.

Abstract Questions Report Heading

1. What was your research hypothesis? Introduction

2. Why did you think that - briefly? Introduction

3. How was the experiment carried out? (include number of replicates and type of data analysis)

Methods

4. What was the result? (support or reject HO) Results

5. What did you conclude? Discussion

Don't try to squeeze everything from your Introduction and Discussion into the Abstract, and certainly don't give the detailed method. Avoid citations in the Abstract.

Example

This experiment was designed to test the hypothesis that brands of paper towels of different materials have different absorbencies. The hypothesis was based on research which indicated different towel materials absorb different amounts of water. Two paper towel brands, Adzorb and Hi-Suck, were tested by measuring the rate of movement of water the towelling. Each brand was tested 10 times and the results were subjected to the Rank Sum Test. The results showed no statistical difference between the brands. It is suggested that a better prediction and improved experimental design would have involved measuring the total amount of water absorbed rather than the rate of absorption.

Some Final Comments

Please remember that the whole point of this exercise is to devise HR, have adequate background literature to support the reasoning behind the HR, to carry out a scientific experiment properly, to analyze the data properly using statistical analysis, and draw conclusions from your results.

Below is a checklist of points to consider when writing your formal laboratory report:

The paper is type-written, double-spaced, 12-point font.

The pages of the report are numbered.

The title is succinct and conveys information on the context of the experiment.

There are headings at the beginning of each section of the laboratory report.

The sections are in the correct sequence (Title, Abstract, Introduction, Methods, Results, Discussion, References).

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You have a minimum of 4 references.

You have a printout of any references from the Web.

The following points are regarding the style of writing:

Be sure to write in a manner appropriate for persons not familiar with the area of research. Be sure to provide sufficient background information.

Remember to define all terms the first time you use them, particularly abbreviations.

Write in 3rd person, passive voice. Do not use ‘we’, ‘I’, or ‘me’.

Write in past tense.

Know when to use ‘effect’ and ‘affect’.

Do not dramatize text of use colloquial language. Do not use adjectives that are not quantifiable such as ‘huge’ or ‘tremendous’.

Try to write the text in as clear, concise manner possible. Lots of words do not make a good paper.

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APPENDIX E: FORMAL LAB REPORT MARKING RUBRIC

Headings Unacceptable Incomplete Acceptable Good Excellent Total Introduction -no cover

-Has no introduction & or background.

-incomplete cover -Has vague introduction

-Has an acceptable cover -Has some introduction

-Has sufficient introduction & or background. -cover page

-Has an extensive introduction with citations

Cover / Introduction

Points 10 0-2 3-4 5-6 7-8 9-10 Methods -Material list very

incomplete. -Material list has some items.

-Material list is complete.

-Material list is complete -has sufficient instruction.

-Material list is complete with amounts required. -Includes concise instructions

Methods

Points 5 0-1 2 3 4 5 Results Missing several of

the following or incomplete. -Data –in labeled chart or table, using correct units. -Data summarized.

Missing more than one of the following or incomplete. -Data –in labeled chart or table, using correct units. -Data

summarized.

-Missing one of the following or incomplete. -Data –in labeled chart or table, using correct units. -Data summarized.

- All of the following done well. -Data –in labeled chart or table, using correct units. -Data

summarized.

-All of the following excellent. -Data –in labeled chart or table, using correct units. -Data summarized.

Results

Points 10 0-2 3-4 5-6 7-8 9-10 Discussion and Conclusion

-does not relate or summarize results -no summarization or recommendations

-Contains part of the results, and weak or vague summary.

-Contains partial summary and results -does not relate findings to introduction or background info -summarizes findings -no recommendation -no explanation

-Explains findings -relates them back to the introduction in a meaningful way. -discuss the results completely-summarizes findings -recommendation or explanation missing

-Discuss the results completely. -Discuss the relationship(s) completely between results and the introduction. -Explain the findings -include citations where

appropriate -concise summary of findings -states recommendations - concise explanation

Discussion/ conclusion

Points 15 0-3 4-6 7-10 11-13 14-15 Abstract -missing or nearly

incomplete -missing more than one reference to the following- intro, findings, results, discussion

-missing one reference to the following- intro, methods, results, and discussion

Includes reference to intro, results, discussion and methods but lacks conciseness

Includes concise summary of the introduction, methods, results and discussion

Abstract

Points 5 0-1 2 3 4 5 Lab Report Format

-spelling mistakes -submitted late -diagrams and figures not labeled -poor grammar -improper sequence

No spelling mistakes On time Diagrams and figures labeled Correct grammar Correct sequence

Lab Report Format

Points 5 0 2 3 4 5

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