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wasario
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The gill lining of lobsters in which the disease-causing parasite An. 22 Jan 2025, 23:37
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75% (02:05) correct 25% (02:09) wrong based on 251 sessions

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The gill lining of lobsters in which the disease-causing parasite An. haemophila resides is completely regenerated every 30 days. The An. haemophila parasite typically produces moderate discoloration of the gills of infected lobsters, and can occasionally lead to more chronic symptoms.
However, because these parasites cannot transfer directly from infected gill lining to newly generated gill lining in their host lobster, any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Which of the following, if true, would most weaken the argument above?

(A) Other parasites are found more frequently in lobsters than An. haemophila.
(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
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D
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SwethaReddyL
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The gill lining of lobsters in which the disease-causing parasite An. 19 Feb 2025, 07:31
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@gmatninja could you please provide an explanation for this
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ManifestDreamMBA
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The gill lining of lobsters in which the disease-causing parasite An. 21 Feb 2025, 10:56
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Conclusion: Any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Pre-thinking: Show that An. haemophila. can still infect after 30days

(A) Other parasites are found more frequently in lobsters than An. haemophila.
We don't care about other parasites

(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
We are not concerned about "parasite-rich" water. We are taking about lobsters in parasite-free water

(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
We are not concerned about about affects caused by An. haemophila. We just want to know if An. haemophila. can be the cause of gill discoloration after lobster's transfer to parasite-free water

(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
This makes sense, this gives a way for An. haemophila. to reinfect even after 30days of transfer to parasite-free water (because it is already inside the lobster and not in the gill lining

(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
Goes in the opposite direction
wasario
The gill lining of lobsters in which the disease-causing parasite An. haemophila resides is completely regenerated every 30 days. The An. haemophila parasite typically produces moderate discoloration of the gills of infected lobsters, and can occasionally lead to more chronic symptoms.
However, because these parasites cannot transfer directly from infected gill lining to newly generated gill lining in their host lobster, any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Which of the following, if true, would most weaken the argument above?

(A) Other parasites are found more frequently in lobsters than An. haemophila.
(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
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The gill lining of lobsters in which the disease-causing parasite An. 22 Feb 2025, 07:58
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BUt we we were talking about gills not the stomach of lobsters ? Can we be 100% sure that when parasite migrates to the stomach and reinfects the lobster it also will discolour the gill ? Most probably it does implie that, but I not sure.
ManifestDreamMBA
Conclusion: Any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Pre-thinking: Show that An. haemophila. can still infect after 30days

(A) Other parasites are found more frequently in lobsters than An. haemophila.
We don't care about other parasites

(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
We are not concerned about "parasite-rich" water. We are taking about lobsters in parasite-free water

(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
We are not concerned about about affects caused by An. haemophila. We just want to know if An. haemophila. can be the cause of gill discoloration after lobster's transfer to parasite-free water

(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
This makes sense, this gives a way for An. haemophila. to reinfect even after 30days of transfer to parasite-free water (because it is already inside the lobster and not in the gill lining

(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
Goes in the opposite direction
wasario
The gill lining of lobsters in which the disease-causing parasite An. haemophila resides is completely regenerated every 30 days. The An. haemophila parasite typically produces moderate discoloration of the gills of infected lobsters, and can occasionally lead to more chronic symptoms.
However, because these parasites cannot transfer directly from infected gill lining to newly generated gill lining in their host lobster, any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Which of the following, if true, would most weaken the argument above?

(A) Other parasites are found more frequently in lobsters than An. haemophila.
(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
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The gill lining of lobsters in which the disease-causing parasite An. 22 Feb 2025, 08:34
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The lobster can be infected irrespective of where An. haemophila resides. The passage just mentioned 2 things:
1. An. haemophila resides in the gill lining
2. An. haemophila infected lobsters develop a discolouration in the gills

An. haemophila doesn't have to reside in the gill to infect the lobster, and hence discolour the gills

Think of it this way: A bug usually bite on the legs. Bug bites lead to fever. So, even if the bug bite on the neck, it will cause fever. The bug doesn't have to necessarily bite on the legs
Johny23
BUt we we were talking about gills not the stomach of lobsters ? Can we be 100% sure that when parasite migrates to the stomach and reinfects the lobster it also will discolour the gill ? Most probably it does implie that, but I not sure.
ManifestDreamMBA
Conclusion: Any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Pre-thinking: Show that An. haemophila. can still infect after 30days

(A) Other parasites are found more frequently in lobsters than An. haemophila.
We don't care about other parasites

(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
We are not concerned about "parasite-rich" water. We are taking about lobsters in parasite-free water

(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
We are not concerned about about affects caused by An. haemophila. We just want to know if An. haemophila. can be the cause of gill discoloration after lobster's transfer to parasite-free water

(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
This makes sense, this gives a way for An. haemophila. to reinfect even after 30days of transfer to parasite-free water (because it is already inside the lobster and not in the gill lining

(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
Goes in the opposite direction
wasario
The gill lining of lobsters in which the disease-causing parasite An. haemophila resides is completely regenerated every 30 days. The An. haemophila parasite typically produces moderate discoloration of the gills of infected lobsters, and can occasionally lead to more chronic symptoms.
However, because these parasites cannot transfer directly from infected gill lining to newly generated gill lining in their host lobster, any discoloration appearing on the gills of lobsters more than 30 days after they have been moved to parasite-free water is not due to infection by An. haemophila.

Which of the following, if true, would most weaken the argument above?

(A) Other parasites are found more frequently in lobsters than An. haemophila.
(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
(D) In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
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The gill lining of lobsters in which the disease-causing parasite An. 15 Apr 2025, 04:02
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The argument is built on a key assumption: that An. haemophila cannot move from the old gill lining to the newly regenerated gill lining. Based on this, it concludes that any gill discoloration appearing more than 30 days after being moved to parasite-free water cannot be due to An. haemophila.
So to weaken this argument, we’re looking for an option that challenges the idea that the parasite cannot infect the new gill lining after 30 days — perhaps by showing it can persist in the lobster or re-infect it in some way.


✅ Correct Answer: (D)
Quote:
In some cases An. haemophila migrates from the gill lining to the stomach, where it can then re-infect its original host.
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  • Why it weakens: If the parasite can hide in the stomach and later re-infect the gills, it undermines the claim that discoloration on newly grown gills after 30 days in clean water must be from something else.
  • This means the infection could persist internally and affect new gill tissue, even without external exposure. So the argument’s conclusion becomes unreliable.

❌ Eliminations:
(A) Other parasites are found more frequently in lobsters than An. haemophila.
  • Irrelevant – This talks about other parasites, not An. haemophila.
  • It doesn’t challenge the idea that this specific parasite cannot survive the 30-day gill regeneration cycle.

(B) Lobsters that remain in parasite-rich waters can be re-infected by new An. haemophila parasites once newly generated gill lining has been produced.
  • This doesn’t weaken the argument because it assumes lobsters are still in parasite-rich waters, but the argument is about lobsters that have been moved to parasite-free water.
  • So this tells us nothing about whether discoloration after 30 days in clean water is due to An. haemophila.

(C) An. haemophila can also cause digestive and respiratory distress in infected lobsters.
  • This is about other symptoms, not gill discoloration.
  • It doesn’t touch the assumption or mechanism of reinfection via gill tissue. So it’s off-topic.

(E) Once infected by a particular parasite, lobsters frequently develop a strong immunity to that parasite allowing them to better resist re-infection.
  • This actually supports the argument by making re-infection less likely.
  • It suggests that lobsters are even less likely to get infected again after 30 days, strengthening the conclusion.
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