Question

scientific method practice problems
many significant problems in science have been solved through the use of the scientific method. read the following scenarios and answer the following questions.
scenario 1
mary investigated the effect of different concentrations of miracle - grow on the growth of tomato plants. mary hypothesized that if higher concentrations of miracle - grow were added, the plants would exhibit poorer growth. she grew four groups of tomato plants (10 plants/group) for 30 days. she then applied miracle - grow as follows:
group a, 0% miracle - grow;
group b, 10% miracle - grow;
group c, 20% miracle - grow; and
group d, 30% miracle - grow.
the plants received the same amount of sunlight and water each day. at the end of 30 days, mary recorded the height of the plants (in centimeters) and the color of the leaves (green, yellow - green, yellow, or brown.)
basic experimental terms: use these terms to answer the following questions
*an independent variable is the variable which is purposefully changed by the experimenter.
*a dependent variable is the variable which responds to the changed variable.
*controlled variables are variables that are not changed during the experiment (constants).
*a control group is the group in the experiment which allows the experimenter to assess the effect of any unforeseen variable. it usually represents
ormal\ conditions.
*an experimental group is any group in an experiment that is different than the control group and has one changed variable.

1. in this scenario, what is the independent variable?
2. what is the dependent variable?
3. in this scenario, what are the controlled variables? (identify at least three.)

Explanation:

1. The independent variable is what the experimenter changes. Here, Mary changes the concentration of Miracle - Grow, so that's the independent variable.
2. The dependent variable responds to the change. The height of the plants and the color of the leaves are affected by the Miracle - Grow concentration, so they are the dependent variables.
3. Controlled variables are kept constant. The amount of sunlight, water, and the number of plants per group are kept the same, so they are controlled variables.

Answer:

1. Concentration of Miracle - Grow
2. Height of the plants and color of the leaves
3. Amount of sunlight, amount of water, number of plants per group