Question 36

[Guest]

I don't know what "into the test" means. Does it mean the first 5 minutes, the last 5, or just any time of 5 minutes during the course.

Please clarify.

[admin]

5 minutes into the test = at the 5 minute mark = 5 minutes after the test started

[jgeng03]

Isn't there growth before the 5 min mark and why is A wrong?

[admin]

[obert823775]

Why couldn't the bacteria lie dormant for 5 minutes, then resume dividing/growing?

[mmcginl7986]

I suppose that realistically speaking, nothing lies dormant for only 5 minutes, particularly bacteria, which will grow exponentially under favorable conditions.

I, however, chose A as incorrect because I don't think that the shape of the graph corresponds to the scenario of having two different food sources. The shape of the graph indicates that one source was used up, then the horizontal plateau indicates no growth, which implies that little or no food was used, followed by growth again as if the colonies' scouts discovered and brought back the second source to their populations. Even if one source is better than another, in a petri dish BOTH sources would have been used from the beginning, so we should have seen a smoother curve and gradual decline into a plateau unless the second source was introduced later.

[enachbe18198]

I too don't see how this graph shows a difference in two types of nutrients...

[dnpgr16513]

I agree with the people above me. Why is A considered correct? If the medium contantained 2 different types of carbohydrates, one which serves as a more OPTIMAL growth source, then wouldn't we see 2 lines and not one? Please clarify..

Thanks!