Question

To see patterns in the data from a time-course experiment like this, it is helpful to graph the data. First, determine which set of data goes on each axis. (a) What did the researchers intentionally vary in the experiment? This is the independent variable, which goes on the x-axis. (b) What are the units (abbreviated) for the independent variable? Explain in words what the abbreviation stands for. (c) What was measured by the researchers? This is the dependent variable, which goes on the y-axis. (d) What does the units abbreviation stand for? Label each axis, including the units.

Short answer

The graph for the time-course experiment is plotted between the independent variable (time) on the x-axis and the dependent variable (phosphate ion concentration) on the y-axis.

1. The researchers varied the time in the experiment. Thus time is the independent variable.
2. The unit for time (independent variable) is min (minute).
3. The researchers measured the concentration of Pi ion in the experiment; thus, Pi concentration is the dependent variable.
4. The unit for Pi concentration is µmol/mL (micro-mol per milliliter).

Step-by-step solution

Explanation for “a”

In the time-course experiment, the researchers varied the time to check the enzyme's activity concerning time. They measured the activity of the enzyme at an interval of 5 minutes.

A variable that can be varied to measure its impact on another variable is called an independent variable.Thus, time is the independent variable that is plotted on the x-axis of the graph.

Explanation for “b”

Time is the independent variable in the graph. The unit of time is minute, and it is abbreviated as min. Thus, time is plotted on the x-axis in min with an interval of 5 minutes.

Explanation for “c”

In the time-course experiment, the researchers measured the concentration of phosphate ions in the buffer at an interval of 5 minutes. This is because the phosphate ion concentration depends on the enzyme activity of the liver cells.

A variable that is measured in the experiment is a dependent variable. Thus, the phosphate ion concentration is the dependent variable plotted on the y-axis of the graph.

Explanation for “d”

The unit of phosphate ion concentration is µmol/mL. µmol/mL is an abbreviation of micromoles per milliliters. µmol/mL means 10^-6 moles per microliter of the buffer.