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Name: _______________________________________________ Hour: _____ Biology Graphing Practice Introduction: Graphing is an important procedure used by scientists to display the data that is collected during a controlled experiment A graph contains 4 major parts: a. Title b. Independent variable c. Dependent variable d. Scales for each variable (…and a legend/key if needed) The Title: depicts what the graph is about. By reading the title, the reader should get an idea about the graph. It should be a concise statement placed above the graph. The Independent Variable: is the variable that can be controlled by the experimenter. (I KNOW THIS MEASUREMENT AT THE BEGINNING OF THE EXPERIMENT!) It usually includes time (dates, minutes, hours), depth (feet, meters), temperature (Celsius). This variable is placed on the X axis (horizontal axis). The Dependent Variable: is the variable that is directly affected by the independent variable. It is the result of what happens because of the independent variable. (YOU DO NOT KNOW THIS MEASUEMENT AT THE BEGINNING OF THE EXPERIMENT!) Example: How many oxygen bubbles are produced by a plant located five meters below the surface of the water? The oxygen bubbles are dependent on the depth of the water (independent). This variable is placed on the Yaxis or vertical axis. The Scales for each Variable: In constructing a graph one needs to know where to plot the points representing the data. In order to do this a scale must be employed to include all the data points. This must also take up a conservative amount of space. The scales should start with 0 and climb based on intervals such as: multiples of 2, 5, 10, 20, 25, 50, or 100. The scale of numbers will be dictated by your data values. The mean for a group of variables: To determine the mean for a group of variables, divide the sum of the variables by the total number of variables to get an average. The median for a group of variables: To determine median or “middle” for an even number of values, put the values in ascending order and take the average of the two middle values. e.g. 2, 3, 4, 5, 9, 10 Add 4+5 (2 middle values) and divide by 2 to get 4.5 The mode for a group of variables: The mode for a group of values is the number that occurs most frequently. e.g. 2, 5, 8, 2, 6, 11 The number 2 is the mode because it occurred most often (twice). 1 Problem #1: Using the following data, answer the questions below and then construct a line graph. Depth in water in meters Number of Bubbles / minute Plant A Number of Bubbles / minute Plant B 2 29 21 5 36 27 10 45 40 16 32 50 25 20 34 30 10 20 1. What is the dependent variable? 2. What is the independent variable? 3. What title would you give the graph? 4. What are the mean, median, and modes for the following data? a). Depth : Mean____________ Median_________ Mode________ b). Bubbles Plant A.: Mean ____________ Median_________ Mode________ c). Bubbles Plant B: Mean ____________ Median_________ Mode________ 5. Construct a line graph Problem #2: Diabetes is a disease affecting the insulin producing glands of the pancreas. If there is not enough insulin being produced by these cells, the amount of glucose in the blood will remain high. A blood glucose level above 140 for an extended period of time is not considered normal. This disease, if not brought under control, can lead to sever complications. Answer the following questions concerning the data below and then graph it. mL of Glucose / L of Blood mL of Glucose / L of Blood Time After Eating (hours) Person A Person B 0.5 170 180 1 155 195 1.5 140 230 2 135 245 2.5 140 235 3 135 225 4 130 200 2 1. What is the dependent variable? 2. What is the independent variable? 3. What title would you give the graph? 4. Which, if any, of the above individuals (A and/or B) has diabetes? 5. What data do you have to support your hypothesis? 6. Construct a line graph Problem #3: Rabbits Over Time a. The graph shows a _______________ growth curve. b. The carrying capacity for rabbits is ____ rabbits. c. During which month were the rabbits in exponential growth? ***Hint: See pg. 93-94 Problem #4: Average Toe Length a. In 1800, about how many people surveyed had a 3 cm toe? __________ How many in 2000? __________ b. The data shows the ________________ selection has occurred? c. In 2000, what is the average toe length? ________ What is the average toe length in 1800 _________? ***Hint: See pg. 408 3 Problem #5: Mexico and US a. In Mexico, what percentage of the population is between 0-4 years of age? _________ In the US? _________ b. Which population is growing the fastest? ____________ c. Which age group has the smallest number in both countries? _________ ***Hint: See pg. 103 Problem # 6: Amount of ethylene in ml/m2 Wine sap Apples: Days to Maturity Golden Apples: Days to Maturity Gala Apples: Days to Maturity 10 14 14 15 15 12 12 13 20 11 9 10 25 10 7 9 30 8 7 8 35 8 7 7 Ethylene is a plant hormone that causes fruit to mature. The data above concerns the amount of time it takes for fruit to mature from the time of the first application of ethylene by spraying a field of trees. 1. Construct a line graph 2. What is the dependent variable? 3. What is the independent variable? 4 Problem # 7: Age of the tree in years Average thickness of the annual rings in cm. Forest A Average thickness of the annual rings in cm. Forest B 10 2.0 2.2 20 2.2 2.5 30 3.5 3.6 35 3.0 3.8 50 4.5 4.0 60 4.3 4.5 The thicknesses of the annual rings indicate what type of environmental situation was occurring at the time of its development. A thin ring usually indicates a rough period of development: Lack of water, forest fires, or a major insect infestation. On the other hand, a thick ring indicates just the opposite. 1. Construct a line graph of the data. 2. What is the dependent variable? 3. What is the independent variable? 4. What was the average thickness of the annual rings of 40 year old trees in Forest A? 5. Based on this data, what can you conclude about Forest A and Forest B? 5 Problem # 1 Title: _______________________________________________________________________ 6 Problem #2 Title: _____________________________________________________________________________ 7 Problem #6 Title: _____________________________________________________________________________ 8 Problem #7 Title: _____________________________________________________________________________ 9