Question

The Fresno Chaffee Zoo is designing a new Hippo River exhibit. They are interested in the possibility of using wetlands areas to provide natural biological filtration (conversion of nitrogenous waste into nitrate and the removeal of nitrate from the system). In this system wetlands grasses would use nitrate from the river water as food, efectively removing it from the river. Research Question: Does sweetgrass or sedge (two wetland grasses) achieve a lower concentration of nitrate in the river water? Classify each of the following variables (a-d) as the dependent, independent, or confounding variables described in this proposed research question.

a) type of grass

b) the amount of grass eaten by the hippos

c) the season

d) the concentration of nitrate in the river

Answer 1

Research Question: Does sweetgrass or sedge (two wetland grasses) achieve a lower concentration of nitrate in the river water? In this question, the researcher wants to investigate the effect of wetland grasses on the concentration variation of nitrate in the river.

Classification of given variables:

a) Type of grass: This is an independent variable. Since the independent variables are those variables that typically have an effect on the dependent variable. In this research, sweetgrass or sedge (two wetland grasses) both may have different capacity to convert the nitrogenous waste into nitrate (natural biological filtration). These wetland grasses would have an effect on lowering the concentration of nitrate in the river, so this is an independent variable.

b) The amount of grass eaten by the hippos: This is also an Independent variable because here the wetland grasses work as natural biological filters and the total amount of grasses has an effect on the concentration variation of nitrate in the river. Therefore, the amount of grass eaten by hippos has an effect on the concentration variation of nitrate and this is an independent variable.

c) The season: This is the confounding variable. A confounding variable is an extra variable that you didn’t account in research. They can ruin an experiment and give you useless results. The confounding variable suggests the correlation but in fact, there is not. Here the season may or may not have an effect on lowering the concentration of nitrate in the river and in this research it is not accounted for.

d) The concentration of nitrate in the river: This is the dependent variable because of the concentration variation of nitrate in the river depends upon the independent variables (for ex- type of grass, total amount of grass)