Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
After just 3 months of studying with the TTP GMAT Focus course, Conner scored an incredible 755 (Q89/V90/DI83) on the GMAT Focus. In this live interview, he shares how he achieved his outstanding 755 (100%) GMAT Focus score on test day.
In this conversation with Ankit Mehra, IESE MBA and CEO & Co-Founder, of GyanDhan, we will discuss how prospective MBA students can finance their MBA education with education loans and scholarships.
Grab 20% off any Target Test Prep GMAT Focus plan during our Flash Sale. Just enter the coupon code FLASH20 at checkout to save up to $320. The offer ends on Tuesday, April 30.
Sayali narrates her experience of succeeding on the GMAT after 4 attempts & 2 years of preparations. Sayali achieved 99 percentile score on GMAT Focus edition after significantly improving her performance in verbal section of the GMAT
What do András from Hungary, Pablo from Mexico, Conner from the United States, Giorgio from Italy, Leo from Germany, and Rishab from India have in common? They all earned top scores on the GMAT Focus Edition using the Target Test Prep course!
What do András from Hungary, Conner from the United States, Giorgio from Italy, Leo from Germany, and Saahil from India have in common? They all earned top scores on the GMAT Focus Edition using the Target Test Prep course!
Milankovitch proposed in the early twentieth century that
[#permalink]
17 Nov 2011, 13:57
Milankovitch proposed in the early twentieth century that the ice ages were caused by variations in the Earth’s orbit around the Sun. For some time this theory was considered untestable, largely because there was no sufficiently precise chronology of the ice ages with which the orbital variations could be matched. To establish such a chronology it is necessary to determine the relative amounts of land ice that existed at various times in the Earth’s past. A recent discovery makes such a determination possible: relative land-ice volume for a given period can be deduced from the ratio of two oxygen isotopes, 16 and 18, found in ocean sediments. Almost all the oxygen in water is oxygen 16, but a few molecules out of every thousand incorporate the heavier isotope 18. When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that will eventually return to it. Because heavier isotopes tend to be left behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18. The degree of enrichment can be determined by analyzing ocean sediments of the period, because these sediments are composed of calcium carbonate shells of marine organisms, shells that were constructed with oxygen atoms drawn from the surrounding ocean. The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down. As an indicator of shifts in the Earth’s climate, the isotope record has two advantages. First, it is a global record: there is remarkably little variation in isotope ratios in sedimentary specimens taken from different continental locations. Second, it is a more continuous record than that taken from rocks on land. Because of these advantages, sedimentary evidence can be dated with sufficient accuracy by radiometric methods to establish a precise chronology of the ice ages. The dated isotope record shows that the fluctuations in global ice volume over the past several hundred thousand years have a pattern: an ice age occurs roughly once every 100,000 years. These data have established a strong connection between variations in the Earth’s orbit and the periodicity of the ice ages. However, it is important to note that other factors, such as volcanic particulates or variations in the amount of sunlight received by the Earth, could potentially have affected the climate. The advantage of the Milankovitch theory is that it is testable; changes in the Earth’s orbit can be calculated and dated by applying Newton’s laws of gravity to progressively earlier configurations of the bodies in the solar system. Yet the lack of information about other possible factors affecting global climate does not make them unimportant.
The author of the passage would be most likely to agree with which of the following statements about the Milankovitch theory? (A) It is the only possible explanation for the ice ages. (B) It is too limited to provide a plausible explanation for the ice ages, despite recent research findings. (C) It cannot be tested and confirmed until further research on volcanic activity is done. (D) It is one plausible explanation, though not the only one, for the ice ages. (E) It is not a plausible explanation for the ice ages, although it has opened up promising possibilities for future research.
It can be inferred from the passage that the isotope record taken from ocean sediments would be less useful to researchers if which of the following were true? (A) It indicated that lighter isotopes of oxygen predominated at certain times. (B) It had far more gaps in its sequence than the record taken from rocks on land. (C) It indicated that climate shifts did not occur every 100,000 years. (D) It indicated that the ratios of oxygen 16 and oxygen 18 in ocean water were not consistent with those found in fresh water. (E) It stretched back for only a million years.
According to the passage, which of the following is true of the ratios of oxygen isotopes in ocean sediments? (A) They indicate that sediments found during an ice age contain more calcium carbonate than sediments formed at other times. (B) They are less reliable than the evidence from rocks on land in determining the volume of land ice. (C) They can be used to deduce the relative volume of land ice that was present when the sediment was laid down. (D) They are more unpredictable during an ice age than in other climatic conditions. (E) They can be used to determine atmospheric conditions at various times in the past.
plz explain
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Re: Milankovitch proposed in the early twentieth century that
[#permalink]
17 Nov 2011, 19:34
1, E. This question, I guess :< 2, D "As an indicator of shifts in the Earth’s climate, the isotope record has two advantages. First, it is a global record: there is remarkably little variation in isotope ratios in sedimentary specimens taken from different continental locations" 3, C "The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down."
Re: Milankovitch proposed in the early twentieth century that
[#permalink]
18 Nov 2011, 12:24
1. D 2. B 3. C Could anyone explaine why 3 is not E? My way - They can be used to determine ice age =>ice age is atmospheric condition => They can be used to determine atmospheric conditions. What is wrong with that? Source - OG page 386
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
gmatclubot
Re: Milankovitch proposed in the early twentieth century that [#permalink]