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Subject Test Biology

Question 9 of 24

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SAT Subject Test

The multiple choice questions have five answer choices — one (and only one) is correct in each case.

The figure presents a graph in the first quadrant of an xy-plane titled The Growth of Bacteria at 37 Degrees Celsius. The horizontal axis is labeled, Time in hours, and is numbered, from left to right, 0 to 16, in increments of 2. The vertical axis is labeled Number of Living Bacteria in Millions, and is numbered, from bottom to top, 0 to 10, in increments of 5. An arrow pointing to the 0 on the horizontal axis is labeled Time of Inoculation. A line is shown on the graph starting at 0 on the horizontal axis and at 0 point 5 on the vertical axis. The line gradually curves up and to the right until it reaches 4 hours on the horizontal axis. The line then curves steeply up and to the right and gradually levels as it approaches a peak at around 8 hours on the horizontal axis. The line then curves down and to the right until it reaches sixteen hours. Some approximate values of the line are as follows: 2 hours, 1 million living bacteria.; 4 hours, 3 million living bacteria.; 6 hours, 9 million living bacteria.; 8 hours, 9 point 5 million living bacteria.; 10 hours, 9 million living bacteria.; 12 hours, 6 million living bacteria.; 14 hours, 2 million living bacteria.; 16 hours, 1 million living bacteria.

In the graph above, the time when the number of living bacteria is increasing at the greatest rate occurs

Select an Answer

during the first 2 hours

Correct Answer: 
No

between the 2nd and the 4th hour

Correct Answer: 
No

between the 4th and the 6th hour

Correct Answer: 
Yes

between the 6th and the 10th hour

Correct Answer: 
No

between the 11th and the 13th hour

Correct Answer: 
No

The greatest rate of bacterial population growth occurs between 4 and 6 hours after inoculation. This question asks when the greatest rate of growth occurred, not when the number of bacteria was greatest. The curve is steepest between 4 and 6 hours after inoculation, making that the time period with the greatest rate of growth.

Question Difficulty: 
medium