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Warm-blooded animals have elaborate physiological controls t
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14 Mar 2018, 14:29
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Warm-blooded animals have elaborate physiological controls to maintain constant body temperature (in humans, 37℃). Why then during sickness should temperature rise, apparently increasing stress on the infected organism? It has long been known that the level of serum iron in animals falls during infection. Garibaldi first suggested a relationship between fever and iron. He found that microbial synthesis of siderophores—substances that bind iron—in bacteria of the genus Salmonella declined at environmental temperatures above 37℃ and stopped at 40.3℃. Thus, fever would make it more difficult for an infecting bacterium to acquire iron and thus to multiply. Cold-blooded animals were used to test this hypothesis because their body temperature can be controlled in the laboratory. Kluger reported that of iguanas infected with the potentially lethal bacterium A. hydrophilia, more survived at temperatures of 42℃ than at 37℃, even though healthy animals prefer the lower temperature. When animals at 42℃ were injected with an iron solution, however, mortality rates increased significantly. Research to determine whether similar phenomena occur in warm-blooded animals is sorely needed.
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63% (02:25) correct
37% (02:20) wrong based on 204 sessions
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The passage is primarily concerned with attempts to determine
(A) the role of siderophores in the synthesis of serum iron (B) new treatments for infections that are caused by A. hydrophilia (C) the function of fever in warm-blooded animals (D) the mechanisms that ensure constant body temperature (E) iron utilization in cold-blooded animals
79% (01:08) correct
21% (01:24) wrong based on 155 sessions
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According to the passage, Garibaldi determined which of the following?
(A) That serum iron is produced through microbial synthesis. (B) That microbial synthesis of siderophores in warm-blooded animals is more efficient at higher temperatures. (C) That only iron bound to other substances can be used by bacteria. (D) That there is a relationship between the synthesis of siderophores in bacteria of the genus Salmonella and environmental temperature. (E) That bacteria of the genus Salmonella require iron as a nutrient.
65% (01:07) correct
35% (01:52) wrong based on 147 sessions
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Which of the following can be inferred about warm-blooded animals solely on the basis of information in the passage?
(A) The body temperatures of warm-blooded animals cannot be easily controlled in the laboratory. (B) Warm-blooded animals require more iron in periods of stress than they do at other times. (C) Warm-blooded animals are more comfortable at an environmental temperature of 37℃ than they are at a temperature of 42℃. (D) In warm-blooded animals, bacteria are responsible for the production of siderophores, which, in turn, make iron available to the animal. (E) In warm-blooded animals, infections that lead to fever are usually traceable to bacteria.
41% (01:21) correct
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If it were to be determined that “similar phenomena occur in warm-blooded animals”, which of the following, assuming each is possible, is likely to be the most effective treatment for warm-blooded animals with bacterial infections?
(A) Administering a medication that lowers the animals’ body temperature (B) Injecting the animals with an iron solution (C) Administering a medication that makes serum iron unavailable to bacteria (D) Providing the animals with reduced-iron diets (E) Keeping the animals in an environment with temperatures higher than 37℃
Re: Warm-blooded animals have elaborate physiological controls t
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20 May 2020, 10:41
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shankar13 wrote:
Carcass wrote:
Quote:
It has long been known that the level of serum iron in animals falls during infection. Garibaldi first suggested a relationship between fever and iron
This is the key relationship that makes C the best answer
The other answers are out of scope or not mentioned in the passage.
Hope now is clear.
Ask if you need further assistance.
if serum iron level falls during infection, why are we administering a medication that makes serum iron "unavailable " to the bacteria
The serum iron levels fall during bacteria because bacteria is utilizing them to reproduce. The passage, and common sense, tells you that fever is not good for the organism ("although healthy animals prefer lower temperatures"). Thus, when the last question asks the most EFFICIENT treatment for warm-blooded, you have to choose between 1) Fever or 2) making iron, bacteria's "food", unavailable. Option 2 avoids the detrimental effects of inducing fever. Plus, the passage also says that when fever-induced iguanas are injected with iron (translated into = more iron available for bacteria), the death rates increase. So, even a fever cannot completely stop the iron-binding properties of bacteria. An increase in available iron, even during fever, compensates for the loss in iron-binding efficiency of bacteria.
Re: Warm-blooded animals have elaborate physiological controls t
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16 Jul 2020, 08:02
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For anyone confused by 27, from what I understand, the body increases its temperature so that it prevents the production of the siderophobes and prevents the bacteria from getting iron; furthermore, the increase in iron causes an increase in mortality so this is evidence that increasing the concentration of iron can counteract the effect of reducing siderophobes/iron binding. So the root of the problem is the bacteria binding (even at high temperatures, it is not completely stopped). Now, I could see either C or D working for 28 but it is much more effective to tackle the root of the problem (bacteria binding to the iron) than to give a low-iron diet, so I put D. E is a tricky choice because we know that the production of Salmonella stops around 40.3 degrees and the experiment on iguanas was done at 42 degrees, so it is not easy to say if any temperature greater than 37 degrees would be okay.
I got 26 wrong too because I was only looking at the first line "Warm-blooded animals have elaborate ... controls to maintain constant body temperature". I was thinking, this does not necessarily mean that warm-blooded animals' temperature cannot be easily controlled! But if we look at lines 13-15, it says that "Cold-blooded animals were used ... because their body can be controlled ...". The word "because" infers that warm-blooded animals may be harder to control.
However, I think C could be a possible answer because it says that "healthy animals prefer the lower temperature". It doesn't specify that warm-blooded or cold-blooded animals prefer it, so I believe it is speaking about both?!
Warm-blooded animals have elaborate physiological controls t
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16 Jul 2020, 11:20
Expert Reply
Q3
Cold-blooded animals were used to test this hypothesis because their body temperature can be controlled in the laboratory.
From this sentence we can easily infer that the warm-blood animal temperature is not easily controlled under testing or laboratory
Which of the following can be inferred about warm-blooded animals solely on the basis of information in the passage?
(A) The body temperatures of warm-blooded animals cannot be easily controlled in the laboratory. (B) Warm-blooded animals require more iron in periods of stress than they do at other times. (C) Warm-blooded animals are more comfortable at an environmental temperature of 37℃ than they are at a temperature of 42℃.
Cold-blooded animals were used to test this hypothesis because their body temperature can be controlled in the laboratory. Kluger reported that of iguanas infected with the potentially lethal bacterium A. hydrophilia, more survived at temperatures of 42℃ than at 37℃, even though healthy animals prefer the lower temperature.
C mentioned that warm-bllod animal were more used to at a temperature of 42C but those animals were the COLD-blood. Those used for the testing.
No where in the passage C is mentioned.
(D) In warm-blooded animals, bacteria are responsible for the production of siderophores, which, in turn, make iron available to the animal. (E) In warm-blooded animals, infections that lead to fever are usually traceable to bacteria.
Q27 I think you overthinking the scenario
The key phrase is the following
Thus, fever would make it more difficult for an infecting bacterium to acquire iron and thus to multiply
Moreover, the passage suggests this
Cold-blooded animals were used to test this hypothesis because their body temperature can be controlled in the laboratory.
Re: Warm-blooded animals have elaborate physiological controls t
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17 Jul 2020, 06:09
For question 26, I was looking here when I got the evidence: Kluger reported that of iguanas infected with the potentially lethal bacterium A. hydrophilia, more survived at temperatures of 42° C than at 37° C, even though healthy animals preferthe lower temperature.
@Carcass, wouldn't you say that "prefer" has the same kind of meaning as "comfortable"?
Re: Warm-blooded animals have elaborate physiological controls t
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21 Jul 2020, 06:28
Regarding problem 27: infecting bacterium (bad guys) need iron to spread. High temperature makes it difficult for infecting bacterium to acquire iron --> this is why temperature rises during sickness (to prevent bacterium from spreading) (A) Administering a medication that lowers the animals' body temperature This is incorrect. We don't want to lower the temperature. This would help bacterium to acquire iron and spread. (C) Administering a medication that makes serum iron unavailable to bacteria This is the correct answer. We don't want bacterium to acquire iron.
Re: Warm-blooded animals have elaborate physiological controls t
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24 Jul 2020, 16:25
Carcass wrote:
To be honest Sir I usually do not infer that much.
prefer= comfortable....it is not properly the same.
I prefer pizza rather than pasta. Am I comfortable ?' mhhhh far-fetched
I prefer to lay on the coach than bed....I am more comfortable on the former. Could be...
It depends.
Bottom line: DO NOT infer too much or try to find a meaning which goes too far. Stay tight to the passage I.E. Do not think too much
Regards
However, in regards to hot vs cold temperatures, if someone prefers cold weather, they are probably comfortable in it. I think context should also matter for those two words?
Re: Warm-blooded animals have elaborate physiological controls t
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16 Jan 2021, 04:45
Truth be told, I was confused by the last question as well, because the idea of producing a medication that makes iron unavailable to bacteria is not hinted at anywhere in the text and seems inherently far-fetched. But since the question assumes all of the following options are possible, then C does seem like the most efficient one.
Re: Warm-blooded animals have elaborate physiological controls t
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17 Jan 2021, 22:44
3
1. A- Role of iron binding agents is not the primary purpose. B- New treatments are never mentioned. Illogical. C- Yes, the function of fever and temperature rises is what is mainly talked about. D- Constant temperature is opposite to what is actually talked about. E- Is just a part, and not the primary purpose.
2. A- Serum iron production is not mentioned in the experiment. B- Warm blooded experiments have not been carried out. Incorrect. C- Totally irrelevant. D- Correct as this is mentioned in the line "microbial synthesis of siderophores—substances that bind iron—in bacteria of the genus Salmonella declined at environmental temperatures above 37℃ and stopped at 40.3℃." E- Trap answer. The bacteria is not of salmonella but attacking it. Also we don't know if the iron is used as a nutrient.
3. A- True because the passage mentions "Cold-blooded animals were used to test this hypothesis because their body temperature can be controlled in the laboratory". From this it can be inferred warm blooded animals' temperatures are harder to control in a lab. B- No info to infer any of this. C- This is true for iguana's, who are cold blooded. D- Just an amalgam of incorrect info. E- No such pattern is mentioned.
4. A- If body temperature is lowered then iron production will increase and this means production of bacteria will also increase. B- This will increase bacteria. Opposite of being treated. C- Correct. If serum iron is unavailable, the bacteria won't be able to bind. D- Reduced iron diets might work but it is not the most effective treatment. E- This only works for iguana's. Not sure if applicable to warm blooded creatures.
gmatclubot
Re: Warm-blooded animals have elaborate physiological controls t [#permalink]