1. A greenhouse experiment was set up in which a series of pots were placed on a
ID: 141356 • Letter: 1
Question
1. A greenhouse experiment was set up in which a series of pots were placed on a tabletop. Each pot contained a similar soil mixture and three bean seedlings of the same size. A total of 12 pots were set up. Different thicknesses of neutral density shade cloth were placed above each pot to allow different amounts of sunlight to reach plants. These different thicknesses were no cloth, single thickness of cloth, and double thickness of cloth. Each of these levels of shade cloth was assigned randomly to pots until each of the 12 pots was assigned a treatment (assume equal numbers of pots in each treatment). On the 14th day of the experiment, leaf thicknesses and plant heights were measured.
a. What is (are) the independent variable(s) in this experiment?
b. What is (are) the dependent variable(s) in this experiment?
c. What are the controlled variables in this experiment?
d. How many replicates (i.e. trials) were there in this experiment?
e. What is the N for the experiment?
2. Student A hypothesized that plants obtained their energy from light and student B hypothesized that plants obtained their energy from nutrients in the soil. They set up the following experiment: Each of group of 5 bean seedlings received different treatments of light and fertilizer. After all the seedlings grew for 21 days, the energy in each group of plants was measured using an instrument called a bomb calorimeter. The treatments and results of the energy measurements are shown below:
Treatment Group A B C D E
Light Intensity 10 20 30 40 50
Fertilizer (grams) 1 2 3 4 5
Energy Content after 21 days (Kcal) 974 1190 1510 2170 2855
a. Which of the following would be the best statement about the data from the students’ experiments?(1 pt)
A. The data contradict student A’s hypothesis but support student B’s hypothesis.
B. The data contradict student B’s hypothesis but support student A’s hypothesis.
C. The data contradict both hypotheses.
D. The data are consistent with both hypotheses.
E. The data show that energy is obtained from both light and fertilizer.
b. Check all of the controlled variables you would include for this experiment (1 pt each)
____ number of seedlings per pot
_____ the type of soil
_____ amount of water
_____ amount of light
_____ same species of plant
_____ amount of fertilizer
_____energy content after 21 days
Explanation / Answer
1.(a)independent variable is the type of cloth used to cover the plant.
(b)leaf thickness and plant heights are dependent variables.
(c)The soil mixture provided is the controlled variable as it is common to all.
(d)There are three trials that are 4 pots without clothes,4 pots with single cloth and 4 pots with double cloths.
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