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28 Feb 2024, 05:18
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A: Species X is susceptible to unusually cold weather whereas Species Y is not.
B: The number of Species Y frogs decreased from the previous spring census.
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
29% (02:16) correct
71%
(02:21)
wrong
based on 1847
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In comparing the results of a recent annual spring census to those of the previous year, biologists observed dramatic changes in the numbers of frogs of two species—Species X and Species Y—and an overall decrease in the combined number of frogs of these species. The biologists hypothesized that this decrease was caused by the unusually cold weather between the two censuses.
Select for A and for B the statements such that the biologists' hypothesis would have the most support if A is true and B is false. Make only two selections, one in each column.
Select for A and for B the statements such that the biologists' hypothesis would have the most support if A is true and B is false. Make only two selections, one in each column.
ID: 700203
| A | B | |
| Species X is susceptible to unusually cold weather whereas Species Y is not. | ||
| Species X has a later mating season than does Species Y. | ||
| Both Species X and Species Y are susceptible to similar contaminants. | ||
| The number of Species X frogs decreased from the previous spring census. | ||
| The number of Species Y frogs decreased from the previous spring census. |
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Official Answer
A: Species X is susceptible to unusually cold weather whereas Species Y is not.
B: The number of Species Y frogs decreased from the previous spring census.
28 Feb 2024, 11:05
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In comparing the results of a recent annual spring census to those of the previous year, biologists observed dramatic changes in the numbers of frogs of two species—Species X and Species Y—and an overall decrease in the combined number of frogs of these species. The biologists hypothesized that this decrease was caused by the unusually cold weather between the two censuses.
The biologists have hypothesized the following:
this decrease was caused by the unusually cold weather between the two censuses
The only information we have about the frogs is the following:
From one spring census to the next there were
- dramatic changes in the numbers of frogs of two species—Species X and Species Y
- an overall decrease in the combined number of frogs of these species
So, we don't know whether the "dramatic changes" involved an increase or decrease in the case of each species, and there's no clear connection between the "unusually cold weather" and the "decrease."
In other words, so far, we have only a correlation between unsually cold weather and an overall decrease, and we know that the biologists have hypothesized that the first caused the second.
Select for A and for B the statements such that the biologists' hypothesis would have the most support if A is true and B is false. Make only two selections, one in each column.
The correct answers can work in a couple of ways.
- A and the negation of B may each on its own confirm the hypothesis.
- Alternatively, A and the negation of B may work together to confirm the hypothesis.
Reviewing the choices, we see the following:
Species X is susceptible to unusually cold weather whereas Species Y is not.
This choice is interesting since it mentions cold weather and provides some confirmation that cold weather could have caused a decrease in the number of frogs of species X.
Species X has a later mating season than does Species Y.
This choice seems irrelevant to the case that the decrease was caused by cold weather.
Both Species X and Species Y are susceptible to similar contaminants.
This choice could possibly weaken the case for believing that the cold weather caused the decrease by indicating that there may have been an alternative cause, "contaminants."
So, negating this choice might strengthen the argument a little.
The number of Species X frogs decreased from the previous spring census.
This choice doesn't make any difference on its own because we already know that there was a decrease, and this choice doesn't indicate what caused the decrease.
The number of Species Y frogs decreased from the previous spring census.
This choice doesn't make any diifference on its own because we already know that there was a decrease, and this choice doesn't indicate what caused the decrease.
So, none of the choices on its own confirms that cold weather caused the decrease. We might get a little confirmation by negating "Both Species X and Species Y are susceptible to similar contaminants," to eliminate an alternative cause, but we don't even know that there were decreases in the number of frogs of both species.
Also, if we choose "Both Species X and Species Y are susceptible to similar contaminants," as the choice to negate, then no other choice would do much to confirm that the decrease was caused by cold weather. After all, the only choice that mentions cold weather is "Species X is susceptible to unusually cold weather whereas Species Y is not," and that choice is not a very good strengthener since it indicates that one species might possibly have been affected by cold weather while the other would not have been.
So, let's see whether there's a better set of choices since those two aren't a very good set.
Considering the choices carefully, we see the following:
If "Species X is susceptible to unusually cold weather whereas Species Y is not," then cold weather would presumably have caused the number of frogs of species X to decrease but not the number of frogs of species Y.
So, if we negate "The number of Species Y frogs decreased from the previous spring census," to create "The number of Species Y frogs DID NOT decrease from the previous spring census," we have great support for the hypothesis.
After all, in that case, since there was an overall decrease in the number of frogs of the two species, we know for sure that the number of frogs of species X DID decrease.
So, what we have then is the following:
- There was cold weather and an overall decrease in the number of frogs of two species.
- The number of frogs of Species X, which is affected by cold weather, decreased.
- The number of frogs of Species Y, which is not affected by cold weather, did not decrease.
Accordingly, we have some solid confirmation that the cold weather is what caused the decrease because the decrease in the number of frogs occurred only in the case of the species affect by cold weather.
For A, select Species X is susceptible to unusually cold weather whereas Species Y is not.
For B, select The number of Species Y frogs decreased from the previous spring census.
The biologists have hypothesized the following:
this decrease was caused by the unusually cold weather between the two censuses
The only information we have about the frogs is the following:
From one spring census to the next there were
- dramatic changes in the numbers of frogs of two species—Species X and Species Y
- an overall decrease in the combined number of frogs of these species
So, we don't know whether the "dramatic changes" involved an increase or decrease in the case of each species, and there's no clear connection between the "unusually cold weather" and the "decrease."
In other words, so far, we have only a correlation between unsually cold weather and an overall decrease, and we know that the biologists have hypothesized that the first caused the second.
Select for A and for B the statements such that the biologists' hypothesis would have the most support if A is true and B is false. Make only two selections, one in each column.
The correct answers can work in a couple of ways.
- A and the negation of B may each on its own confirm the hypothesis.
- Alternatively, A and the negation of B may work together to confirm the hypothesis.
Reviewing the choices, we see the following:
Species X is susceptible to unusually cold weather whereas Species Y is not.
This choice is interesting since it mentions cold weather and provides some confirmation that cold weather could have caused a decrease in the number of frogs of species X.
Species X has a later mating season than does Species Y.
This choice seems irrelevant to the case that the decrease was caused by cold weather.
Both Species X and Species Y are susceptible to similar contaminants.
This choice could possibly weaken the case for believing that the cold weather caused the decrease by indicating that there may have been an alternative cause, "contaminants."
So, negating this choice might strengthen the argument a little.
The number of Species X frogs decreased from the previous spring census.
This choice doesn't make any difference on its own because we already know that there was a decrease, and this choice doesn't indicate what caused the decrease.
The number of Species Y frogs decreased from the previous spring census.
This choice doesn't make any diifference on its own because we already know that there was a decrease, and this choice doesn't indicate what caused the decrease.
So, none of the choices on its own confirms that cold weather caused the decrease. We might get a little confirmation by negating "Both Species X and Species Y are susceptible to similar contaminants," to eliminate an alternative cause, but we don't even know that there were decreases in the number of frogs of both species.
Also, if we choose "Both Species X and Species Y are susceptible to similar contaminants," as the choice to negate, then no other choice would do much to confirm that the decrease was caused by cold weather. After all, the only choice that mentions cold weather is "Species X is susceptible to unusually cold weather whereas Species Y is not," and that choice is not a very good strengthener since it indicates that one species might possibly have been affected by cold weather while the other would not have been.
So, let's see whether there's a better set of choices since those two aren't a very good set.
Considering the choices carefully, we see the following:
If "Species X is susceptible to unusually cold weather whereas Species Y is not," then cold weather would presumably have caused the number of frogs of species X to decrease but not the number of frogs of species Y.
So, if we negate "The number of Species Y frogs decreased from the previous spring census," to create "The number of Species Y frogs DID NOT decrease from the previous spring census," we have great support for the hypothesis.
After all, in that case, since there was an overall decrease in the number of frogs of the two species, we know for sure that the number of frogs of species X DID decrease.
So, what we have then is the following:
- There was cold weather and an overall decrease in the number of frogs of two species.
- The number of frogs of Species X, which is affected by cold weather, decreased.
- The number of frogs of Species Y, which is not affected by cold weather, did not decrease.
Accordingly, we have some solid confirmation that the cold weather is what caused the decrease because the decrease in the number of frogs occurred only in the case of the species affect by cold weather.
For A, select Species X is susceptible to unusually cold weather whereas Species Y is not.
For B, select The number of Species Y frogs decreased from the previous spring census.
28 Feb 2024, 23:52
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Iwillget770
This is how I would evaluate it:
- biologists observed dramatic changes in the numbers of frogs of two species—Species X and Species Y—and an overall decrease in the combined number of frogs of these species.
Given that overall number decreased but not given whether both X and Y decreased or one decreased etc.
Hypothesis: unusually cold weather between the two censuses
I need to provide support to the hypothesis by giving two statements - 'Statement A' and 'Inverse of Statement B.'
Reading the 5 statements stand alone, I am not sure what to pick. So I come back to statement 1 thinking that perhaps two statements together will make sense. Species X is susceptible to unusually cold weather whereas Species Y is not.
It does talk about X being susceptible to cold and hence does support that cold weather could be the culprit. It wil make more sense if we find out that Y did not decrease. Then we know that X decreased a lot and is responsible for most of the reduction in number. We have another statement:The number of Species Y frogs decreased from the previous spring census.
Inverse of this would be 'number of Y did not decrease'.
Now if we put all this info together, does the hypothesis make more sense?
- Overall number of frogs decreased.
- Speices Y did not decrease (which means that X plunged)
- X is susceptible to cold but Y is not.
It does seem that the unusually cold weather could be the reason for the decrease.
Hence these two statements are the answer.
