Final answer:
The experiment on gibberellins' effect on tomato plant growth includes a control group treated with water, an independent variable (GA concentration), a dependent variable (apical growth), and controlled variables such as the growth environment. The findings have implications for the commercial use of gibberellins in agriculture.
Step-by-step explanation:
In an experiment attempting to learn the effect of gibberellic acid (GA) on apical growth in tomato plants, several components are essential to understand:
- The control group in this experimental design is Plant 1, which was treated with water. This group serves as the standard for comparison to observe the effect of GA.
- The independent variable is the concentration of GA applied to the plants since this is the factor that the researcher changes purposely.
- The dependent variable is the apical growth of the tomato plants, which is what the researcher measures to see the effect of the independent variable.
- One example of a controlled variable would be the environment in which the plants are grown (25 ℃ under 12:12 light-dark conditions for 7 days), as it is important for these factors to remain constant to isolate the effect of the GA.
The observation that the plant with 1% GA had the greatest increase in height suggests that increasing concentrations of GA can lead to an increase in apical growth of tomato plants. This can help understand the commercial use of gibberellins in agriculture, such as using them to spray grapes for oversized fruit. The reason for this commercial application is that gibberellins promote shoot elongation and increase fruit size, which could potentially make the crops more profitable.