Water

Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since virtually every living organism requires oxygen to survive, it is a necessary component of water systems such as streams, lakes and rivers in order to support aquatic life. The dissolved oxygen is measure in units of ppm—or parts per million. Examine the data in Table 2 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from; finally, answer the questions below.

Table 2: Water Quality vs. Fish Population

Dissolved Oxygen (ppm) 0 2 4 6 8 10 12 14 16 18

Number of Fish Observed 0 1 3 10 12 13 15 10 12 13

Questions

1. Develop a hypothesis relating the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water. (10 points)

If you increase the amount of dissolved oxygen in the water sample, then more fish will be observed due to the fish needs of oxygen for cellular respiration.

2. What would your experimental approach be to test this hypothesis? In other words, describe the experiment you would carry out in order to test your hypothesis. (10 points)

I would create a series of aquariums with diverse levels of dissolved oxygen (starting from 0ppm to 10ppm) and maybe one with the conditions that freshwater would have. I would either place 80-100 minnows or mollies in each tank/aquarium. Record data on a daily basis of the number of fish in each tank. I would experiment for a 5-7 days and then remove any dead fish from the tank/aquarium.

3. What are the independent and dependent variables? (10 points)

Independent Variable: Amount of dissolved oxygen

Dependent Variable: Number of fish observed

4. What type of graph would be appropriate for this dataset? Why? (10 points)

A line graph will be appropriate because it supports the hypothesis and provided results.

5. Graph the data from the table...