About the Laboratory Manual Interpreting and Recording Data Laboratory Drawings Exercise #1

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1 Name: Date: Period: About the Laboratory Manual As you begin working in the biology laboratory, you will engage in a great variety of activities. You will perform many types of experiments and investigations. In doing these experiments and investigations, you will observe, compare, record, and interpret data and conduct library research. You will also form hypotheses and draw conclusions based on these activities. The Laboratory Investigations in this manual provide you with the opportunity to investigate biological problems by using the same techniques and approaches that scientists might use in their laboratories. Interpreting and Recording Data All observations you make during a laboratory investigation must be recorded. These recorded observations are your biological data. It is important to record and organize your data clearly, logically, and completely so that the data can be used to formulate conclusions. Data can be recorded in different ways. The following sections and exercises explain some of the operations that you will use to record data. Laboratory Drawings Laboratory drawings can be made using several methods, depending on a particular Laboratory Investigation. Some drawings are made in circles that represent the viewing field of a microscope or other type of magnifier. When completing these drawings, be sure to include the magnification at which you viewed the object. Other laboratory drawings are representative of entire organisms or parts of organisms. These drawings show the relative size, shape, and location of anatomical structures. When completing representative drawings, make the structures clear and as accurate as possible. Most laboratory drawings are labeled. Use the following guidelines to help make your laboratory drawings clear and legible. Use a ruler to draw and label lines Label lines should point to the center of the structure being labeled. Do not write on the label lines Print all labels horizontally Label the right-hand side of the drawing, if possible Do not cross label lines Exercise #1 The following laboratory drawing was completed without the guidelines for laboratory drawings. Circle those parts of the drawing that do not follow the guidelines. Then, explain how these parts should be done properly. Explanations:

2 Data Tables Data tables record information in an organized manner. Each data table should have a title. Within the table, the columns and rows should have appropriate headings. The headings given to the rows and columns indicate where particular data are to be placed. Therefore, the data table can be understood and interpreted easily by reading the title of the data table and the column and row headings. Exercise #2 Given the following information, organize the data into a table. Use the blank table provided in Figure 2 to draw in the necessary columns and rows. Then, interpret the data and answer the questions that follow. Information: On an expedition around the world, several scientists collected the venom of various snakes. One of the tests that the scientists conducted determined the toxicity of the venom of each snake. Other data obtained by the scientists included the mortality percentage, or relative death rate, from the bites of various snakes. The snakes observed were (1) the southern United States copperhead, (2) the western diamondback rattlesnake, (3) the eastern coral snake, (4) the king cobra, (5) the Indian krait, (6) the European viper, (7) the bushmaster, (8) the ferde-lance, (9) the black necked cobra, and (10) the puff adder. The mortality percentages of people bitten by the snakes varied from 100% to less than 1%. The scientists noted the mortality percentage for each of the snakes was (1) less than 1%, (2) 5-15%, (3) 5-20%, (4) greater than 40%, (5) 77%, (6) 1-5%, (7) usually 100%, (8) 10-20%, (9) 11-40%, and (10) 11-40%. Interpretations 1. Which snake(s) venom has the highest mortality rate? 2. Which snake(s) venom has the lowest mortality rate? 3. From the information recorded, can you determine the snake whose venom works the most rapidly? The least rapidly? 4. Which two snakes venom has the same mortality rate? 5. How many snakes were observed? Graphs Recorded data can be plotted on a graph. Graphs show a comparison or relationship between 2 or more different factors. In several of the Laboratory Investigations, you will need to draw and then interpret a line graph and a bar graph. Figure 3 contains examples of these 2 types of graphs. Figure 2

3 Figure 3: Examples of a line graph and a bar graph Use the following guidelines for organizing and drawing graphs. On both line and bar graphs you must draw two lines, a horizontal and a vertical line. The horizontal line is the x-axis and the vertical line is the y-axis. Each axis must be labeled to indicate what it represents. Use graph paper or a grid containing equally spaced squares Provide a title for the graph that clearly explains what the graph depicts. The x-axis and y-axis usually have a numerical scale with appropriate units. However, on some graphs the x-axis or y-axis may be labeled rather than having a numerical scale. Exercise# 3 Use Graphs 1 and 2 in Figure 4 to answer the following questions. INTERPRETATIONS FOR GRAPH 1 1. When no potassium is added to the soil, approximately what is the potato yield?

4 2. What happens to the potato yield per hectare as more potassium is added to the soil? 3. Approximately, what is the potato yield when 200 kg/ha of potassium has been added to the soil? INTERPREATIONS FOR GRAPH 2 1. At birth, what is the average number of RBC per mm³ of blood? 2. What appears to happen to the number of RBCs between birth and death? 3. What happens to the number of RBCs between the ages of six and eight? 4. After 14 years of age, do males or females have a higher RBC count? Determining Averages Occasionally, an average of data recorded during an experiment is needed. To find an average, add the number of items in a group, and then divide the total by the number of items. For example, in a garden the heights of six sunflowers are 135 cm, cm, 180 cm, 235 cm, 185 cm, and cm. To find the average height of the sunflowers, add the heights of the sunflowers and divide by the total number of sunflowers. What is the average height of the sunflowers? Your answer should be cm. Exercise# 4 Find the average for the following group of data. Then use the results to answer the questions that follow. In an experiment on plant growth and overcrowding, plants of the following heights are in three equal-sized containers. Flower Pot 1: 20 cm and 18 cm Flower Pot 2: 12 cm, 10.8 cm, 11.2 cm, 12.4 cm Flower Pot 3: 7.5 cm, 8 cm, 6 cm, 6.2 cm, 5.8 cm, 7.3 cm INTERPRETATIONS 1. What is the average height of the plants in each flower pot? 2. In which flower pot did the plants grow the tallest? Explain. Exercise 5 Find the average for the following group of data. Express your answers to the nearest tenth. In a sample group of students, the number of breaths per minute was taken at rest and after exercise. The results were as follows. At Rest Males: 10.1, 13, 12.5, 10.2, 13.1, 11.8 Females: 10.4, 13, 12.1, 11.9, 10.5, 12.8 After Exercise: Males: 18.9, 23.7, 22.6, 21.3, 19.2, 20.6 Females: 25, 26.7, 29, 35.3, 33.1, 31.7 INTERPRETATIONS 1. What is the average number of breaths per minute for males at rest? Females at rest? 2. What is the average number of breaths per minute for males after exercise? Females after exercise? 3. How many students make up the sample group? 4. What is the average number of breaths per minute for the entire group at rest? After exercise? 5. Do males or females take more breaths per minute at rest? After exercise?

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