Introduction
Biology is a science and biologists use the scientific method. The scientific method involves observing, making a hypothesis, and testing the hypothesis through experimentation. Most scientific observations must be quantified and recorded as numbers. Numbers provide an objective means by which to analyze the information provided by the observations made.
During this exercise you will organize data, calculate means, and prepare various graphs. Often you will be asked to prepare frequency distributions. A frequency distribution indicates the number of observations in each category observed. Remember there are different ways to graph frequency distributions. A bar graph uses columns proportional to the frequency of observations of each category represented. A histogram is similar to a bar graph but with the sides of the columns touching. A pie chart is organized like a pie with the size of each slice proportional to the frequency in the class represented. Whichever method you use to graph your data, you must be sure to label your graph and indicate the scale of measurement you use.
Example
Red Cross determined the blood type of 151 individuals and want to graph the frequency distribution using a bar graph. The graph representing the data is below.
Remember:
Y-axis is dependent
X- axis is independent
Scenario One
Suppose that a researcher wanted to determine the frequency distribution of blood types in 10 males and 10 females at random using a standard antibody antigen procedure. Below is an example of what the agglutination (clumping) looks like between the blood-antigen interactions.
Compare the results below for each subject with the standards that are shown above so that you can determine the blood types of each subject.
Males: Type: Females: Type:
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- Determine the frequency of each blood type for each sex and organize the data. Tabulate the total number of males and then the number of females with blood types A, B, AB, and O.
| A | B | AB | O | |
| Males | ||||
| Females | ||||
| Total |
- Now, use a histogram below to show the frequency of blood types for each sex. Make sure to label properly.
- Now, use the pie chartbelow to show the percentage of each blood type. Combine the sexes and be sure to label each piece of the pie. Use the following formula to calculate percentage:
Part_
Whole x 100 = _____ %
Show your calculations.
A=
B=
AB=
O=
Scenario Two
Suppose that you perform an experiment that requires the measurement of the movement of a liquid in a tube. You are asked to determine the rate of movement in centimeters per minute and the cumulative movement for the entire time period. Movement per minute is just what it sounds like: how many centimeters the liquid moved during a given minute. Cumulative movement requires keeping track of the total amount of movement from the very beginning to the current minute. The results of the experiment are in the table below.
| Time (min.) | Movement Per Minute (cm) | Cumulative Movement (cm) |
| 0 | 0 | 0 |
| 1 | 2 | 2 |
| 2 | 5 | 7 |
| 3 | 3 | 10 |
| 4 | 8 | |
| 5 | 4 | |
| 6 | 0 | |
| 7 | 1 | |
| 8 | 6 | |
| 9 | 4 | |
| 10 | 1 |
- Complete the table above
Below is an example of a line graph showing the movement/minute data from previous table.
- Prepare a line graph for the same data graphing the cumulative distance moved during the 10 minute period. Make sure to label properly.
Scenario Three
A study was conducted to determine whether or not there is a difference in the flea population found on urban dogs (city) versus rural dogs (country). Random dogs were selected and the number of fleas was determined. The fleas were examined microscopically and the sex of each flea was recorded. The results of the study are given below:
Flea Analysis
| Urban Dogs | Rural Dogs | ||||||
| Dog # | F-fleas | M-fleas | Total fleas | Dog # | F-fleas | M-fleas | Total fleas |
| 1 | 15 | 9 | 1 | 73 | 34 | ||
| 2 | 39 | 29 | 2 | 13 | 6 | ||
| 3 | 12 | 6 | 3 | 66 | 50 | ||
| 4 | 30 | 44 | 4 | 74 | 86 | ||
| 5 | 4 | 2 | 5 | 15 | 14 | ||
| 6 | 40 | 50 | 6 | 55 | 56 | ||
| 7 | 82 | 83 | 7 | 20 | 25 | ||
| 8 | 25 | 9 | 8 | 0 | 3 | ||
| 9 | 15 | 15 | 9 | 65 | 67 | ||
| 10 | 18 | 22 | 10 | 54 | 37 | ||
| Total | Total |
- Complete the above table.
- How many total dogs were used in this study?
- How many total fleas were found on the urban dogs?
- How many total male fleas were found on the rural dogs?
- How many dogs in the total study had more than 70 fleas?
- How many dogs in the total study had 27 fleas or less?
Show your work for questions 19 – 23:
- What is the mean number of fleas per dog in the total study?
- What is the mean number of female fleas per urban dog?
- What is the mean number of female fleas per rural dog?
- What is the mean number of male fleas per urban dog?
- What is the mean number of male fleas per rural dog?
- Graph the above means (answers to questions 19-23) below using a bar graph. Make sure to label properly.
- What are two conclusions you can draw from the data in this study?
a.
b.
Scenario Four
A scientist must not only be able to graph his or her own data but also be able to interpret the graphs of other scientists. In this example you will try interpreting data from the graph below.
- Use the Total deaths line in the graph above to complete the table below:
| Year | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 |
- How many years does this study span? __________
- How many years have more than 600 deaths? __________
- What is the total death count for this study? __________
- Which year has the least amount of deaths? ___________
- Which year has the highest amount of deaths? __________
- Showing your work below, what was the mean amount of deaths for this study?
