Dolphins

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Dolphins

by maihuna » Mon Dec 14, 2009 6:41 am
In polluted environments, dolphins gradually accumulated toxins in their body fat,
and the larger the dolphin the more accumulated toxin it can tolerate. Nearly 80
percent of the toxins a female dolphin has accumulated pass into the fat-rich milk her
nursing calf ingests. Therefore, the unusually high mortality rate among dolphin
calves in the industrially contaminated waters along Florida's Gulf Coast is probably
the result of their being poisoned by their mother's milk.
Which of the following, if true, most strengthens the argument?
A. The survival rate of firstborn dolphin calves in the area along Florida's Gulf
Coast is highest for those whose mothers were killed before they were
weaned.
B. The rate at which adult dolphins living in the waters along Florida's Gulf
Coast accumulate toxins is no higher than that of adult dolphins in comparably
polluted waters elsewhere.
C. Among dolphin calves born in the area along Florida's Gulf Coast, the
mortality rate is highest among those with living siblings.
D. As dolphins age, they accumulate toxins from the environment more slowly
than when they were young.
E. Dolphins, like other marine mammals, have a higher proportion of body fat
than do most land mammals.
[spoiler]Answer:A[/spoiler]
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by gmatv09 » Mon Dec 14, 2009 7:57 am
[spoiler]A ==> since the cause (mothers' milk) is eliminated the effect (infant mortality) is also eliminated[/spoiler]

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by arora007 » Tue Jul 27, 2010 3:49 am
I selected A eventhough I did not understand the meaning of "weaned" just on the basis of
survival rate of firstborn dolphin calves
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by reply2spg » Tue Jul 27, 2010 6:20 am
weaning means feeding milk
arora007 wrote:I selected A eventhough I did not understand the meaning of "weaned" just on the basis of
survival rate of firstborn dolphin calves
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by outreach » Tue Jul 27, 2010 6:55 am
A
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by ashforgmat » Wed Jan 26, 2011 3:01 am
Its A since the survival rate is higher for calves who are not being fed their mother's milk ....

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by maddy2u » Tue Feb 15, 2011 1:01 pm
A shouldn't be the answer as weaning doesn't mean Feeding Mother's milk. It actually means the opposite.

weaning - the act of substituting other food for the mother's milk in the diet of a child or young mammal

Answer should be B.

The reason for that is that if other places with the same pollution affect bear the same mortality rate, then it reinforces the argument which says that Pollution is the reason for the higher mortality rate.

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by chendawg » Tue Feb 15, 2011 2:05 pm
maddy2u wrote:A shouldn't be the answer as weaning doesn't mean Feeding Mother's milk. It actually means the opposite.

weaning - the act of substituting other food for the mother's milk in the diet of a child or young mammal

Answer should be B.

The reason for that is that if other places with the same pollution affect bear the same mortality rate, then it reinforces the argument which says that Pollution is the reason for the higher mortality rate.
I agree with you that weaned actually means to be taken off nursing, however, B is not the correct answer. A is still the answer, the author just misused the meaning of wean incorrectly. A is the answer here because if weaned were used correctly, the answer tells us the survival rate for dolphin calves who were not nursed is higher than that for dolphin calves who were nursed. This gives the best support for the author who believes that the dolphin calves are dying because of the nursing.

If B were true, it doesn't affect the conclusion any, as the conclusion states, the unusually high mortality rate among dolphin calves in the industrially contaminated waters along Florida's Gulf Coast is probably the result of their being poisoned by their mother's milk. It's not just about the pollution in the water that affects the argument, but rather how the dophin calves are receiving the contaminants, in this case through the mother's milk.

B states, the rate at which adult dolphins living in the waters along Florida's Gulf Coast accumulate toxins is no higher than that of adult dolphins in comparably polluted waters elsewhere. This basically just says adult dophins living in FL's gulf coast absorbs toxins at a rate no higher than that of adult dolphins elsewhere with the same amount of pollution. This doesn't say anything about having the same mortality rate of other places. We can't assume that without having been told that. Knowing that adult dolphins aborb at the same rate in other places doesn't affect the author's argument that it's the method of being poisoned that's what's killing the dolphin calves.

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by maddy2u » Wed Feb 16, 2011 2:05 am
A. The survival rate of firstborn dolphin calves in the area along Florida's Gulf Coast is highest for those whose mothers were killed before they were weaned.

A doesn't strengthen the argument. According to A ,the dolphins could have already fed on mother's milk and not yet adjusted to the new pattern . If they tend to survive better, then the high mortality rate could not be attributed to the contaminated Mother's milk.

My Two cents

and ya, I accept B is also not that great. but by POE , it seemed better compared to other options.

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by maddy2u » Wed Feb 16, 2011 2:11 am
@chendawg : you mean to tell me the QUESTION Itself is wrong ! thats a big waste then .. :((

Whats the source for this question ?

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by fitzgerald23 » Wed Feb 16, 2011 5:50 am
maddy2u wrote:A. The survival rate of firstborn dolphin calves in the area along Florida's Gulf Coast is highest for those whose mothers were killed before they were weaned.

A doesn't strengthen the argument. According to A ,the dolphins could have already fed on mother's milk and not yet adjusted to the new pattern . If they tend to survive better, then the high mortality rate could not be attributed to the contaminated Mother's milk.

My Two cents

and ya, I accept B is also not that great. but by POE , it seemed better compared to other options.
There is some confusion here over what A is actually saying. I think what A is saying is that the mother died before the calvess were naturally going to be taken off the milk. As an example imagine that the normal dolphin drinks milk for 6 months before the weaning process begins. They are then weaned for 3 months. That means the normal dolphin gets 6 months of poisoned milk and 3 months of a partial diet of toxic milk. If the mother dies before weaning it means those dolphins received less bad milk. It means at least 3 less months of toxic milk and perhaps more depending on how early the mother passes away. So this gives you the direct correlation between toxins and the death rate.

B gives you no relevant information. The question deals specifically with calves. B just talks about adult dolphins.

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by chendawg » Wed Feb 16, 2011 11:11 am
fitzgerald23 wrote: There is some confusion here over what A is actually saying. I think what A is saying is that the mother died before the calvess were naturally going to be taken off the milk. As an example imagine that the normal dolphin drinks milk for 6 months before the weaning process begins. They are then weaned for 3 months. That means the normal dolphin gets 6 months of poisoned milk and 3 months of a partial diet of toxic milk. If the mother dies before weaning it means those dolphins received less bad milk. It means at least 3 less months of toxic milk and perhaps more depending on how early the mother passes away. So this gives you the direct correlation between toxins and the death rate.

B gives you no relevant information. The question deals specifically with calves. B just talks about adult dolphins.
I completely didn't even think about this scenario. This definitely throws out my idea the author using weaning incorrectly. With this scenario A definitely strengthens the argument.

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by maddy2u » Wed Feb 16, 2011 11:24 am
fitzgerald23 : Your explanation is good. Thanks,

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by badpoem » Wed Apr 13, 2011 9:44 am
IMO (A)

(A) The survival rate of firstborn dolphin calves in the area along Florida's Gulf Coast is highest for those whose mothers were killed before they were weaned.--> on Hold. --> now if the mother is killed before the baby has her milk, the indications are that the poisonous milk is what is responsible for the deaths.

(B) The rate at which adult dolphins living in the waters along Florida's Gulf Coast accumulate toxins is no higher than that of adult dolphins in comparably polluted waters elsewhere.
--> comparison of rates out of scope.

(C) Among dolphin calves born in the area along Florida's Gulf Coast, the mortality rate is highest among those with living siblings. ---> doesn't really strengthen. --> On second thoughts, highest among siblings - Nope, does not strengthen.

(D) As dolphins age, they accumulate toxins from the environment more slowly than when they were young. --> out of scope. Not interested in how the toxins are accumulated.

(E) Dolphins, like other marine mammals, have a higher proportion of body fat than do most land mammals. ---> Out of scope again. Land animals?

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by tgou008 » Tue May 10, 2011 12:43 pm
I think this is clearly A

The conclusion of the passage is --> high mortality rate of dolphin babies on florida's gulf coast due to toxins passed through mother's milk

A) strengthens this conclusion by stating that the survival rate is greatest among dolphin babies whose mother's were killed before they were weaned. What this essentially means is that they babies didn't have as much poisonous / toxin filled milk as other babies - therefore less likely to die. This supports the conclusion that I laid out above.

TG