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BS 105 Plant Experiment Assignment
Use the class average data provided in the table to complete this assignment. There are two parts as follows:
1. Your responses to the questions given below. Your answers to the questions MUST be typed and
double-spaced throughout. Answers that are not typed will receive a grade of zero. Number your answers
to correspond with the number of the questions. You do not have to retype the questions! Include your
name and section number in the upper right-hand corner of your paper.
2. Preparation of two graphs of the data. Suggestions for preparation of the graphs are provided on the back of
this page and will be discussed during lab.
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The first graph should depict the effect of seed number on percent germination of the seeds.
(10 points)

The second graph should depict the effect of plant number on mean biomass per plant.
(10 points)

It is strongly recommended that you complete both graphs before you begin preparation of your answers
to the questions.

This is NOT a group assignment. You MUST work independently in preparation of the graphs and
typed responses.

Please staple your typed answers to your graphs. The correct order should be typed answers
followed by figure 1 (the first graph) and then figure 2 (the second graph).
1. When conducting an experiment a researcher first states the hypothesis about how the experiment will turn
out. The hypothesis is typically stated as two possible outcomes, the null hypothesis (H0) and the alternate
hypothesis (H1). Based upon the data, the researcher will then accept one hypothesis and reject the other.
An example is given below.
 A study was conducted of freshmen students to see if there would be an improvement in individual test
scores when the students were placed in supervised study groups at the start of the semester. Half of
the students were assigned to study groups and half were not.

null hypothesis (H0) = Placement in study groups will result in no improvement in student test scores

alternate hypothesis (H1) = Placement in study groups will result in improvement in student test scores.
QUESTION: For the experiment we conducted with the radish plants, clearly state the null hypothesis (H0) and
the alternate hypothesis (H1), in a format similar to the example provided above. Since we have two dependent
variables in this experiment, you should have two null hypotheses and two alternate hypotheses. (4 points)
2. In a controlled experiment we can describe three types of variables: independent, dependent, and
controlled. Clearly identify the independent variable (only 1), dependent variables (only 2), and controlled
variables (at least 3) in the radish plant experiment. (6 points)
3. On the basis of examination of the graphical data, which hypotheses do you accept and which hypotheses
do you reject? EXPLAIN your answer. (4 points)
4. If you examine the raw data closely you’ll notice some seemingly impossible results. Identify this anomaly
and offer a plausible explanation, and then dentify at least one other sources of potential error during the
experiment. (2 points)
5. The data collected allow us to draw a conclusion regarding intra-specific competition of radish plants.
Describe one "real world" situation where experiments like this could be helpful or informative. In other
words, describe how the results of this experiment could be applicable in the “real world”. (4 points)
GRAPHING DATA
The class performed an experiment concerning intra-specific competition of radish plants. You are to graph
the data collected from that experiment. You should have two graphs; one for the biomass per plant data and
the second for the percent germination data. You must use computer graphing software to assist you. There are
numerous graphing programs available, including Microsoft Excel and Microsoft Word. Graphs that are hand
drawn will receive a grade of zero. Below are several suggestions to help you prepare high quality graphs.
1.
Decide whether you have "continuous" or "categorical" data.
Continuous data can assume an infinite range of numerical values (e.g., temperature, distance,
weight, etc.). Categorical data fall into discrete categories (e.g., sex, blood type, political party, etc.).
Continuous data are best presented by line graphs and categorical data are best presented by bar graphs.
2.
Draw in the axes and label the axes.
The labels should clearly indicate what values are plotted on each axis (e.g., mean weight per plant).
The axis labels should also include the appropriate units (e.g., grams per plant).
3.
Use a good sense of proportionality.
The x axis (abscissa) and y axis (ordinate) should be roughly equal in length. Do not make the
abscissa 5 cm long and the ordinate 50 cm long.
4.
Make good use of space on the sheet of paper.
Each graph should essentially fill the page. Do not make a 5 cm x 5 cm graph in one corner of a
sheet of paper that is 20 cm x 25 cm.
5.
Include a title.
A descriptive title is a vital part of any graph. Tell the reader what data are being presented by the
graph.
6.
Do not "smooth" the curves.
Connect the dots for your true data points. Do not guess or interpolate a hypothetical curve unless
you have done the appropriate statistical calculations to fit the line.
7.
By convention, the dependent variable is plotted on the ordinate and the independent
variable is plotted on the abscissa.
The ordinate is the vertical Y-axis and the abscissa is the horizontal X-axis. The independent
variable is what you manipulate, while the dependent variable is what you measure to determine an
outcome. The dependent variable "depends" on values of the independent variable.
8.
BE NEAT!
A very neat, clean, well-done graph leaves a good impression. A graph that is all crumpled or
covered with coffee stains leaves a bad impression.