WHAT WOULD BE THE INDEPENDENT AND DEPENDENT VARIABLES?

29 Jul WHAT WOULD BE THE INDEPENDENT AND DEPENDENT VARIABLES?

Dissolved oxygen is oxygen that is trapped in a fluid,
such as water. Since many 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 measured in units of ppm
(parts per million). Examine the data in Table 4 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.

Post-Lab Questions

1. What
patterns do you observe based on the information in Table 4?

2. Develop
a hypothesis relating to the amount of dissolved oxygen measured in the water
sample and the number of fish observed in the body of water.

3. What
would your experimental approach be to test this hypothesis?

4. What
would be the independent and dependent variables?

5. What
would be your control?

6. What
type of graph would be appropriate for this data set? Why?

7. Graph
the data from Table 4: Water Quality vs. Fish Population (found at the
beginning of this exercise).

8. Interpret
the data from the graph made in Question 7.

Exercise 2: Experimental
Variables

Determine the variables tested in the each of
the following experiments. If applicable, determine and identify any positive
or negative controls.

Observations

1. A
study is being done to test the effects of habitat space on the size of fish
populations. Different sized aquariums are set up with six goldfish in each
one. Over a period of six months, the fish are fed the same type and amount of
food. The aquariums are equally maintained and cleaned throughout the
experiment. The temperature of the water is kept constant. At the end of the
experiment the number of surviving fish is surveyed.

A. Independent
Variable:

B. Dependent
Variable:

C. Controlled
Variables/Constants:

D. Experimental
Controls/Control Groups:

2. To
determine if the type of agar affects bacterial growth, a scientist cultures E.
colion four different types of agar. Five petri dishes are set up to
collect results:

§ One
with nutrient agar and E. coli

§ One
with mannitol-salt agar and E. coli

§ One
with MacConkey agar and E. coli

§ One
with LB agar and E. coli

§ One
with nutrient agar but NO E. coli

All of the petri dishes received the same
volume of agar, and were the same shape and size. During the experiment, the
temperature at which the petri dishes were stored, and at the air quality
remained the same. After one week the amount of bacterial growth was measured.

A. Independent
Variable:

B. Dependent
Variable:

C. Controlled
Variables/Constants:

D. Experimental
Controls/Control Groups:

Exercise 3: Testable Observations

Determine which of the following
observations (1-6) are testable. For those that are testable answer the
following questions:

Determine if the observation is
qualitative or quantitative

Write a hypothesis and null hypothesis

What would be your experimental
approach?

What are the dependent and independent
variables?

What are your controls – both positive
and negative?

How will you collect your data?

How will you present your data (charts,
graphs, types)?

How will you analyze your data?

Observations

1. A
plant grows three inches faster per day when placed on a window sill than it
does when placed on a on a coffee table in the middle of the living room.

2. The
teller at the bank with brown hair and brown eyes is taller than the other
tellers.

3. When
Sally eats healthy foods, her blood pressure is 10 points lower than when she
eats fatty foods.

4. The
Italian restaurant across the street closes at 9 pm but the one two blocks away
closes at 10 pm.

5. For
the past two days, the clouds have come out at 3 pm and it has started raining
at 3:15 pm.

6. George did not sleep at all the night following the
start of daylight savings.

Exercise 4: