The old belief that climatic stability accounts for the high level of

Question

The old belief that climatic stability accounts for the high level of species diversity in the Amazon River basin of South America emerged, strangely enough, from observations of the deep sea. Sanders discovered high diversity among the mud-dwelling animals of the deep ocean. He argued that such diversity could be attributed to the absence of significant fluctuations in climate and physical conditions, without which the extinction of species should be rare. In the course of time new species would continue to evolve, and so the rate of speciation would be greater than the rate of extinction, resulting in the accumulation of great diversity. Sanders argued that the Amazon tropical rain forest is analogous to the deep sea: because the rain forest has a stable climate, extinction should be rare. Evidence that some species of rain-forest trees have persisted for some 30 million years in the Amazon basin, added to the absence of winter and glaciation, supports this view.

Recently however, several observations have cast doubt on the validity of the stability hypothesis and suggest that the climate of the Amazon basin has fluctuated significantly in the past. Haffer noted that different species of birds inhabit different corners of the basin in spite of the fact that essentially unbroken green forest spreads from the western edge to the eastern edge of the region. This pattern presented a puzzle to biologists studying the distributions of plants and animals: why would different species inhabit different parts of the forest if the habitat in which they lived had a stable climate?

Haffer proposed a compelling explanation for the distribution of species. Observing that species found on high ground are different from those on low ground and knowing that in the Amazon lowlands are drier than uplands, he proposed that during the ice ages the Amazon lowlands became a near-desert arid plain; meanwhile, the more elevated regions became islands of moisture and hence served as refuges for the fauna and flora of the rain forest. Populations that were once continuous diverged and became permanently separated. Haffer’s hypothesis appears to explain the distribution of species as well as the unusual species diversity. The ice-age refuges would have protected existing species from extinction. But the periodic geographic isolation of related populations (there have been an estimated 13 ice ages to date) would have facilitated the development of new species as existing species on the lowlands adapted to changing climates.

Although no conclusive  proof  has yet been found to support Haffer’s hypothesis, it has led other researchers to gauge the effects of climatic changes, such as storms and flooding, on species diversity in the Amazon basin. Their research suggests that climatic disturbances help account for the splendid diversity of the Amazon rain forest.   1 
 1. As discussed in the first paragraph of the passage, Sanders’ analogy between the deep sea and the Amazon basin involves which one of the following assumptions?

(A) Both the Amazon basin and the deep sea support an unusually high rate of speciation.
(B) Both the rain-forest trees in the Amazon basin and the mud-dwelling animals in the deep sea have survived for 30 million years.
(C) Both the deep sea and the Amazon basin have not experienced dramatic changes in climate or physical conditions.
(D) A dependable supply of water to the Amazon basin and the deep sea has moderated the rate of extinction in both habitats.
(E) The rate of speciation in the Amazon basin is equivalent to the rate of speciation in the deep sea.

2 
 2. The author of the passage would most likely agree with which one of the following statements about Haffer’s hypothesis?

(A) It provides an intriguing and complete explanation for the high rate of species diversity in the Amazon basin.
(B) It is partially correct in that a number of climatic disturbances account for species diversity in the Amazon basin.
(C) It has not yet been verified, but it has had an influential effect on current research on species diversity in the Amazon basin.
(D) It is better than Sanders’ theory in accounting for the low rate of species extinction in the Amazon basin.
(E) It provides a compelling explanation for the distribution of species in the Amazon basin but does not account for the high species diversity.

3 
 3. According to the passage, lowlands in the Amazon basin currently differ from uplands in which one of the following respects?

(A) Lowlands are desertlike, whereas uplands are lush.
(B) Lowlands are less vulnerable to glaciation during the ice ages than are uplands.
(C) Uplands support a greater diversity of species than do lowlands.
(D) Uplands are wetter than are lowlands.
(E) Uplands are more densely populated than are lowlands.

4 
 4. Which one of the following best describes the organization of the passage?

(A) A hypothesis is discussed, evidence that undercuts that hypothesis is presented and a new hypothesis that may account for the evidence is described.
(B) A recently observed phenomenon is described, an explanation for that phenomenon is discussed, and the explanation is evaluated in light of previous research findings.
(C) Several hypotheses that may account for a puzzling phenomenon are described and discounted, and a more promising hypothesis is presented.
(D) A hypothesis and the assumptions on which it is based are described, and evidence is provided to suggest that the hypothesis is only partially correct.
(E) Two alternative explanations for a phenomenon are presented and compared, and experiments designed to test each theory are described.

5 
 5. The author of the passage mentions the number of ice ages in the third paragraph most probably in order to

(A) provide proof that cooler and drier temperatures are primarily responsible for the distribution of species in the Amazon
(B) explain how populations of species were protected from extinction in the Amazon basin
(C) explain how most existing species were able to survive periodic climatic disturbances in the Amazon basin
(D) suggest that certain kinds of climatic disturbances cause more species diversity than do other kinds of climatic disturbances
(E) suggest that geographic isolation may have occurred often enough to cause high species diversity in the Amazon basin

6 
 6. The passage suggests that which one of the following is true of Sanders’ hypothesis?

(A) He underestimated the effects of winter and glaciation in the Amazon basin on the tropical rain forest.
(B) He failed to recognize the similarity in physical conditions of the Amazon lowlands and the Amazon uplands.
(C) He failed to take into a count the relatively high rate of extinction during the ice ages in the Amazon basin.
(D) He overestimated the length of time that species have survived in the Amazon basin.
(E) He failed to account for the distribution of species in the Amazon basin.

7

7. Which one of the following is evidence that would contribute to the “proof” ( Highlighted ) in the passage?

(A) Accurately dated sediment cores from a freshwater lake in the Amazon indicate that the lake’s water level rose significantly during the last ice age.
(B) Data based on radiocarbon dating of fossils suggest that the Amazon uplands were too cold to support rain forests during the last ice age.
(C) Computer models of climate during global ice ages predict only insignificant reductions of monsoon rains in tropical areas such as the Amazon.
(D) Fossils preserved in the Amazon uplands during the last ice age are found together with minerals that are the products of an arid landscape.
(E) Fossilized pollen from the Amazon lowlands indicates that during the last ice age the Amazon lowlands supported vegetation that needs little water rather than the rain forests they support today.

tapasgupta · Answer

1. As discussed in the first paragraph of the passage, Sanders’ analogy between the deep sea and the Amazon basin involves which one of the following assumptions? we are looking for the similar line "because the rain forest has a stable climate"

(A) Both the Amazon basin and the deep sea support an unusually high rate of speciation  - out of scope
 (B) Both the rain-forest trees in the Amazon basin and the mud-dwelling animals in the deep sea have survived for 30 million years.  - this is not the assumption. it is the proof. Out of scope
 (C) Both the deep sea and the Amazon basin have not experienced dramatic changes in climate or physical conditions.  - similar to our prediction
 (D) A dependable supply of water to the Amazon basin and the deep sea has moderated the rate of extinction in both habitats.  - out of scope
 (E) The rate of speciation in the Amazon basin is equivalent to the rate of speciation in the deep sea.  - out of scope

2. The author of the passage would most likely agree with which one of the following statements about Haffer’s hypothesis?

(A) It provides an intriguing and  complete explanation  for the high rate of species diversity in the Amazon basin. - Inconsistent
(B) It is  partially correct  in that a number of climatic disturbances account for species diversity in the Amazon basin. - author did not said that it is correct. Inconsistent
 (C) It has not yet been verified, but it has had an influential effect on current research on species diversity in the Amazon basin.  - as explained in last para
(D) It is  better than Sanders’ theory  in accounting for the low rate of species extinction in the Amazon basin. - no comparison is done - Inconsistent
(E) It  provides a compelling explanation  for the distribution of species in the Amazon basin but does not account for the high species diversity. - author writes about the compelling explanation. He is not agreeing to it which is asked in the question. Hence Inconsistent.

3. According to the passage, lowlands in the Amazon basin currently differ from uplands in which one of the following respects?

(A) Lowlands are desertlike, whereas uplands are lush.  - Inconsistent
(B) Lowlands are  less vulnerable  to glaciation during the ice ages than are uplands. - Inconsistent
 (C) Uplands support a greater diversity of species than do lowlands.  - out of scope
 (D) Uplands are wetter than are lowlands.  - this is stated in the passage.
 (E) Uplands are more densely populated than are lowlands.  - out of scope

4. Which one of the following best describes the organization of the passage?

(A) A hypothesis is discussed, evidence that undercuts that hypothesis is presented and a new hypothesis that may account for the evidence is described.  - this is the main idea and organization of the passage.
(B) A recently observed  phenomenon  is described, an explanation for that phenomenon is discussed, and the explanation is evaluated in light of previous research findings. - Inconsistent
(C) Several hypotheses that may account for a puzzling phenomenon are described and discounted,  and a more promising hypothesis is presented.  - Inconsistent
(D) A hypothesis and the assumptions on which it is based are described, and evidence is provided to suggest  that the hypothesis is only partially correct.  - Inconsistent
 (E) Two alternative explanations for a phenomenon are presented and compared, and experiments designed to test each theory are described.  - out of scope

5. The author of the passage mentions the number of ice ages in the third paragraph most probably in order to - we are looking for the similar line "But the periodic geographic isolation of related populations (there have been an estimated 13 ice ages to date) would have facilitated the development of new species as existing species on the lowlands adapted to changing climates."

(A)  provide proof that cooler and drier temperatures are primarily responsible  for the distribution of species in the Amazon - Inconsistent
 (B) explain how populations of species were protected from extinction in the Amazon basin  - out of scope
 (C) explain how most existing species were able to survive periodic climatic disturbances in the Amazon basin  - out of scope
 (D) suggest that certain kinds of climatic disturbances cause more species diversity than do other kinds of climatic disturbances  - out of scope
 (E) suggest that geographic isolation may have occurred often enough to cause high species diversity in the Amazon basin  - similar to what we are looking for.

6. The passage suggests that which one of the following is true of Sanders’ hypothesis?

(A) He underestimated the effects of winter and glaciation in the Amazon basin on the tropical rain forest.  - out of scope
 (B) He failed to recognize the similarity in physical conditions of the Amazon lowlands and the Amazon uplands.  - out of scope
 (C) He failed to take into a count the relatively high rate of extinction during the ice ages in the Amazon basin.  - out of scope
 (D) He overestimated the length of time that species have survived in the Amazon basin.  - out of scope
 (E) He failed to account for the distribution of species in the Amazon basin.  - as stated in the 2nd para

7. Which one of the following is evidence that would contribute to the “proof” (Highlighted) in the passage? We are basically looking for the answer choice which provides the evidence for the distribution of species hypothesis by Haffer to be valid

(A) Accurately dated sediment cores from a freshwater lake in the Amazon indicate that the  lake’s water level rose  significantly during the last ice age. - Inconsistent. rise in water level does not account as a evidence for distribution of species 
(B) Data based on radiocarbon dating of fossils suggest that the Amazon uplands  were too cold  to support rain forests during the last ice age. - same as above
 (C) Computer models of climate during global ice ages predict only insignificant reductions of monsoon rains in tropical areas such as the Amazon.  - out of scope
(D) Fossils preserved in the Amazon  uplands  during the last ice age are found together with minerals that are the products of an  arid  landscape. - opposite
(E) Fossilized pollen from the Amazon lowlands indicates that during the last ice age the Amazon  lowlands supported vegetation that needs little water  rather than the rain forests they support today. - this line can be the evidence or proof for the hypothesis to hold valid

Skywalker18 · Answer

All correct in 11 mins 40 seconds, including 3 mins 30 seconds to read.

Para 1- climatic stability leads to high level of species diversity, Sanders compares Amazon to deep sea
Para 2- doubts on the stability hypothesis, Haffer - distributions of plants and animals
Para 3- Haffer's explanation- lowland and upland
Para 4- no conclusive proof but researchers are exploring and concur

1. As discussed in the first paragraph of the passage, Sanders’ analogy between the deep sea and the Amazon basin involves which one of the following assumptions?
(C) Both the deep sea and the Amazon basin have not experienced dramatic changes in climate or physical conditions.

Sanders argued that the Amazon tropical rain forest is analogous to the deep sea: because the rain forest has a stable climate, extinction should be rare

2. The author of the passage would most likely agree with which one of the following statements about Haffer’s hypothesis?
(C) It has not yet been verified, but it has had an influential effect on current research on species diversity in the Amazon basin

Although no conclusive proof has yet been found to support Haffer’s hypothesis, it has led other researchers to gauge the effects of climatic changes, such as storms and flooding, on species diversity in the Amazon basin

3. According to the passage, lowlands in the Amazon basin currently differ from uplands in which one of the following respects?
(D) Uplands are wetter than are lowlands.

Amazon lowlands are drier than uplands

4. Which one of the following best describes the organization of the passage?
(A) A hypothesis is discussed, evidence that undercuts that hypothesis is presented and a new hypothesis that may account for the evidence is described.

5. The author of the passage mentions the number of ice ages in the third paragraph most probably in order to
(E) suggest that geographic isolation may have occurred often enough to cause high species diversity in the Amazon basin

the more elevated regions became islands of moisture and hence served as refuges for the fauna and flora of the rain forest. Populations that were once continuous diverged and became permanently separated. Haffer’s hypothesis appears to explain the distribution of species as well as the unusual species diversity. The ice-age refuges would have protected existing species from extinction. But the periodic geographic isolation of related populations (there have been an estimated 13 ice ages to date) would have facilitated the development of new species as existing species on the lowlands adapted to changing climates.

6. The passage suggests that which one of the following is true of Sanders’ hypothesis?
(E) He failed to account for the distribution of species in the Amazon basin.

Haffer noted that different species of birds inhabit different corners of the basin in spite of the fact that essentially unbroken green forest spreads from the western edge to the eastern edge of the region.

7. Which one of the following is evidence that would contribute to the “proof” (Highlighted) in the passage?
(E) Fossilized pollen from the Amazon lowlands indicates that during the last ice age the Amazon lowlands supported vegetation that needs little water rather than the rain forests they support today.

he proposed that during the ice ages the Amazon lowlands became a near-desert arid plain; meanwhile, the more elevated regions became islands of moisture and hence served as refuges for the fauna and flora of the rain forest.

auradediligodo · Answer

Hi everyone,
Got 6/7 correct in 17 minutes.

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P1

Paragraph one explains an old belief according to which the high number of different species found in the amazon basin has something to do with evidence found in the deep see. Sanders argued that the absence of climatic changes is responsible for such high number because, in the absence of such changes, extinction should be quite rare.
The reason why the deep sea is studied is that also in this environment there is not significant climatic change and the rate of speciation is higher than the rate of extinction.

Brief summary:  An old belief is presented

P2

Paragraph 2 introduces a  contrast . Recent evidence suggested that the climate actually fluctuated significantly in the past. In support of this view, scientists are puzzled about the fact that different species of birds live in different areas of the basin. This wouldn't make sense if the climate were always stable. Haffer conducted the study related to this new view.

Brief summary: The old belief is contrasted by Haffer's study

P3

Paragraph 3 explains more in detail Haffer's study. Haffer studied lowlands and upper lands, noting that there were different species living on the upper lands and lowlands and that upper lands were less dry. Haffer concluded that during the ice ages lowlands became desert like. Such ice ages led to the separation of species and obliged many species to go the less dry upper lands. In addition we are given that Haffer's study not only explains the distribution aspect discussed in P2 but also the species diversity found in the basin. As a matter of fact the species that during the ice ages remained on the lowlands, adapted to the environmental changes and evolved into new species.

Brief summary:  Haffer's study in detail seems to explain species distribution and species diversity

P4

We are given that Haffer study does not give conclusive proof but it has challenged scientists to study how climate change can affect the species diversity in the basin.

Brief summary:  Haffer's study is not conclusive but it prompted more research.

Main point

The main point is to challenge an old belief with recent evidence coming from Haffer's study

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1. As discussed in the first paragraph of the passage, Sanders’ analogy between the deep sea and the Amazon basin involves which one of the following assumptions?

Pre-thinking

Assumption question

From the first paragraph we are given that there are some similarities between the deep sea and the amazon basin that led Sanders think that the rate of speciation is higher than the rate of extinction. Such reasoning is supported by the view according to which in the amazon basin the climate did not significantly change in the past. Hence we would expect that also in the deep see there were not climatic changes in the past.

(A) Both the Amazon basin and the deep sea support an   unusually   high rate of speciation.
 Not in line with pre thinking

(B) Both the rain-forest trees in the Amazon basin and the mud-dwelling animals in the deep sea have survived for 30 million years.
 Too extreme

(C)   Both the deep sea and the Amazon basin have not experienced dramatic changes in climate or physical conditions.
 in line with pre thinking

(D) A dependable supply of water to the Amazon basin and the deep sea has moderated the rate of extinction in both habitats.
 Not in line with pre thinking

(E) The rate of speciation in the Amazon basin is   equivalent   to the rate of speciation in the deep sea.
 Not in line with pre thinking

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2. The author of the passage would most likely agree with which one of the following statements about Haffer’s hypothesis?

Pre-thinking

Inference question

Let's evaluate the answer choices

(A) It provides an intriguing and   complete   explanation for the high rate of species diversity in the Amazon basin.
 Per the last paragraph, Haffer's study is incomplete

(B)  It is partially correct  in that a number of climatic disturbances account for species diversity in the Amazon basin.
 The only drawback of Haffer's theory is that there is no conclusive proof but the author does not dispute the results

(C)   It has not yet been verified, but it has had an influential effect on current research on species diversity in the Amazon basin.
 In line with last paragraph

(D) It is   better   than Sanders’ theory in accounting for the low rate of species extinction in the Amazon basin.
 The two studies are never compared in terms of which one is the best

(E) It provides a compelling explanation for the distribution of species in the Amazon basin  but does not account for the high species diversity. 
 Last part of this option is wrong. Hence inconsistent

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3. According to the passage, lowlands in the Amazon basin currently differ from uplands in which one of the following respects?

Pre-thinking

Detail question

From P3: "  Observing that species found on high ground are different from those on low ground and knowing that in the Amazon lowlands are drier than uplands,  "

(A) Lowlands are desertlike, whereas uplands are lush.
 Not in line with pre-thinking

(B) Lowlands are less vulnerable to glaciation during the ice ages than are uplands.
 Not in line with pre-thinking

(C) Uplands support a greater diversity of species than do lowlands.
 Not in line with pre-thinking

(D)   Uplands are wetter than are lowlands.
 in line with pre-thinking

(E) Uplands are more densely populated than are lowlands.
 Not in line with pre-thinking

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4. Which one of the following best describes the organization of the passage?

Pre-thinking

Structure question

An old belief is presented along with an explanation for it----> new evidence seems to dispute the old belief----> the explanation for the new theory is presented---> Such theory is declared incomplete but challenging for new studies

(A) A hypothesis is discussed, evidence that undercuts that hypothesis is presented and a new hypothesis that may account for the evidence is described.
 This option matches our pre-thought structure even if it lacks of the last part. This option is a good candidate to be the correct answer

(B) A   recently observed   phenomenon is described, an explanation for that phenomenon is discussed, and the explanation is evaluated in light of previous research findings.
 Sanders' view is not recent. Out

(C)   Several   hypotheses that may account for a puzzling phenomenon are described and discounted, and a more promising hypothesis is presented.
 Just one hypothesis. Out

(D) A hypothesis and the assumptions on which it is based are described,  and evidence is provided to suggest that the hypothesis is only partially correct. 
 Not in line with pre-thinking

(E) Two alternative explanations for a phenomenon are presented and compared,  and experiments designed to test each theory are described. 
 No experiment is presented

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5. The author of the passage mentions the number of ice ages in the third paragraph most probably in order to

Pre-thinking

Purpose question

The purpose is to detail the climatic changes that occurred in the past and stress their contribution to species diversity

(A) provide proof that cooler and drier temperatures are primarily responsible for the distribution of species in the Amazon
 Not in line with pre-thinking

(B) explain how populations of species were protected from extinction in the Amazon basin
 Not in line with pre-thinking

(C) explain how most existing species were able to survive periodic climatic disturbances in the Amazon basin
 Not in line with pre-thinking

(D) suggest that certain kinds of climatic disturbances cause more species diversity  than do other kinds of climatic disturbances 
 Not in line with pre-thinking

(E)   suggest that geographic isolation may have occurred often enough to cause high species diversity in the Amazon basin
 in line with pre-thinking

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6. The passage suggests that which one of the following is true of Sanders’ hypothesis?

Pre-thinking

Inference question

Let's evaluate the answer choices

(A) He  underestimated  the effects of winter and glaciation in the Amazon basin on the tropical rain forest.
 Cannot be inferred since Sanders believed there were no winters and no glaciations

(B) He failed to recognize the similarity in physical conditions of the Amazon lowlands and the Amazon uplands.
 We cannot infer such statement

(C) He failed to take into a count the relatively high rate of extinction during the ice ages in the Amazon basin.
 No high rate of extinction is mentioned in the passage

(D) He overestimated the length of time that species have survived in the Amazon basin.
 Cannot be inferred

(E)   He failed to account for the distribution of species in the Amazon basin.
 This aspect is what led haffer to structure the study. hence correct

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7. Which one of the following is evidence that would contribute to the “proof” (Highlighted) in the passage?

Pre-thinking

Strengthen question

From last paragraph: "  The ice-age refuges would have protected existing species from extinction. But the periodic geographic isolation of related populations (there have been an estimated 13 ice ages to date) would have facilitated the development of new species as existing species on the lowlands adapted to changing climates.  
 "

This portion of last paragraph is Haffer's hypothesis and we need to strengthen it

(A) Accurately dated sediment cores from a freshwater lake in the Amazon indicate that the lake’s water level rose significantly during the last ice age.
 Irrelevant

(B) Data based on radiocarbon dating of fossils suggest that the Amazon uplands were too cold to support rain forests during the last ice age.
 This option weakens Haffer's study

(C) Computer models of climate during global ice ages predict only insignificant reductions of monsoon rains in tropical areas such as the Amazon.
 Irrelevant

(D) Fossils preserved in the Amazon uplands during the last ice age are found together with minerals that are the products of an arid landscape.
 Minerals makes this option irrelevant

(E)   Fossilized pollen from the Amazon lowlands indicates that during the last ice age the Amazon lowlands supported vegetation that needs little water rather than the rain forests they support today.
 This option suggests that some species in the lowland were successful in adapting to the ice ages. This option is definitely a strengthener.

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It is a good day to be alive!

Sajjad1994 · Answer

Explanation

7. Which one of the following is evidence that would contribute to the “proof” (Highlighted) in the passage?

Explanation

(E)  is consistent with Haffer’s hypothesis as it’s described in  Paragraph 3 . Haffer proposes that during the ice ages the lowlands saw significant climate changes: They became desert-like, while the uplands were lush refuges. Those changes, Haffer theorizes, would explain species diversity and distribution. If fossilized pollen from desert-loving plants was found in the lowlands, that would jibe with (and thus support) Haffer’s explanation.

(A)  isn’t specific enough. And if the rising lake levels occurred in the lowlands, that would weaken Haffer’s theory.

(B)  would definitely weaken Haffer’s theory: He argues that the uplands became lush refuges, hospitable to existing rain forest species.

(C)  would also tend to weaken Haffer, who argues that the lowlands became very dry.  “Insignificant”  reductions of monsoon rains would not result in desert-like conditions.

(D)  Yet another weakener: Haffer believes that during the last ice age the uplands were lush, not arid.

Answer: E

VerbalBot · Answer

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