The multiple choice questions have five answer choices — one (and only one) is correct in each case.
Three students added equal volumes of pond water to each of four beakers (I–IV) and placed each in a different constant temperature bath, maintained at , , , and , respectively. The students then added water fleas, Daphnia pulex, to each of the four beakers and recorded the time in each case. After hour, the students removed Daphnia pulex from each beaker and each student immediately observed one Daphnia pulex under low-power magnification of a light microscope. (The transparent body of the Daphnia pulex can be seen easily under a light microscope.)
Heart rates were recorded as beats per minute. The results of the experiment are summarized in the chart below.
|Beaker||Temperature||Time Daphnia Added||Time Daphnia Removed||Heartbeats Per Minute
(average of 3 Daphnia)
|I||2:00 p.m.||3:00 p.m.||41|
|II||2:10 p.m.||3:10 p.m.||119|
|III||2:20 p.m.||3:20 p.m.||202|
|IV||2:30 p.m.||3:30 p.m.||281|
If a graph is constructed using the data given in the table, it will most closely resemble which of the following?
Select an Answer
In a graph, the independent variable is usually plotted on the x-axis and the dependent variable on the y-axis. The data in the table show the heartbeat per minute increasing with increased temperature, with the average heartbeat per minute increased by about 80 heartbeats per every increase in temperature. The graph in choice (B), which shows a steady increase in average heartbeat with rise in temperature, accurately reflects the data given in the table.