4) Question: Would more carbon dioxide help a plant grow taller? Hypothesis: If a plant receives more carbon dioxide than normal then it will grow larger than a group receiving normal levels of carbon dioxide.
• Experiment: Rodger is studying the effect of increased carbon dioxide on plant growth. He sets up four tanks (terrariums). Each tank has the same type of plant, same potting soil, same amount of water, same amount of sunlight. The first tank has normal levels of Carbon dioxide. The second tank has 25% more carbon dioxide, the third 50% more and the fourth 100% more. Darren records plant height after each week for a four-week period.
a. What was the independent variable?
b. What was the dependent variable?
c. What was the control?
d. Was there a constant variable?