Despite an abundance of major nutrients in the surface waters of parts

Question

Despite an abundance of major nutrients in the surface waters of parts of the ocean, extremely low concentrations of dissolved iron are believed to play a crucial role in limiting the biological productivity of these regions. Phytoplankton, the basis of freshwater food chains and the source of most of Earth's atmospheric oxygen, require iron for various biochemical processes. Thus, a lack of iron in surface waters has detrimental effects.
 
In temperate and tropical oceans, iron reaches surface waters via the dissolution of eolian-transported continental dust. Previously, little was known about iron distribution in the surface waters of non-temperate oceans such as the Arctic Ocean. Recent advances, however, have resulted in an analytical methodology capable of determining iron concentrations in ambient surface waters. Studies indicate that concentrations across the Arctic Basin are relatively high and quite variable, ranging from 3.2 nM in the western Arctic to 0.75 nM in the Nansen Basin.
 
The highest values of iron concentration occur in regions with ice floes containing significant quantities of surface sediment. The hypothesis that ice-rafted sediment is the source of high iron values is bolstered by the presence of large amounts of aluminum in the same regions. The entrainment of sediments from the edge of the basin into floes during the winter freezing process along with the subsequent advection and partial melting of the ice at the center of the basin provides a means of transporting reactive trace metals, such as iron, to the center of the basin. The partial melting of floes during the summer appears sufficient to transport high concentrations of iron to both surface and stratified waters. It seems, however, that any change resulting in the diminution of ice-edge freezing in winter might lead to significant changes in the nature and magnitude of primary productivity in the central Arctic.   1 
 1. It can be inferred from the passage that an example of a detrimental effect in the highlighted text would be

(a) a decrease in the supply of Earth's atmospheric oxygen 
(b) a decrease in the significance of phytoplankton in the food chain
(c) an increase in the rate at which phytoplankton perform biochemical processes
(d) an increase in the dissolution of eolian-transported continental dust
(e) an increase in biological productivity in the surface waters of parts of the remote ocean

2 
 2. The passage is chiefly concerned with

(a) arguing against the increased production of surface sediment in order to transport iron through surface waters
(b) presenting possible causes for and effects of variations in iron concentrations in surface waters
(c) advocating stricter regulations governing the preservation of phytoplankton in oceanic surface waters
(d) analyzing methods that can effectively measure the amount of iron in surface waters
(e) recommending ways to ensure that iron is transported throughout oceans based upon recent advances in analytical methodology

3 
 3. The passage suggests which of the following about surface waters of temperate oceans?

(a) They do not display an even distribution of iron.
(b) They did not contain iron before recent advances in the development of analytical methodology.
(c) They would display lower concentrations of iron if eolian activity decreased.
(d) They would display higher concentrations of iron if continental dust rose to the surface.
(e) They would not contain iron if ice-rafted sediment did not melt.

4 
 4. It can be inferred from the passage that which of the following would provide the LEAST support for the idea that surface sediment is responsible for increased concentrations of iron in the Arctic Ocean?

(a) The observation that significant quantities of sediment are present on the surface of ice floes in the western Arctic
(b) The observation that a warmer winter results in decreased concentrations of iron in the western Arctic
(c) Measurements taken in the central Arctic confirming that concentrations of iron increase when ice melts
(d) Measurements taken during the summer in the Nansen Basin displaying the highest concentrations of aluminum
(e) The observation that there are higher concentrations of aluminum in the Nansen Basin than in the western Arctic

5 
 5. The passage mentions each of the following about iron EXCEPT:

(a) The hypothesis that ice-rafted sediment is the source of high iron values is bolstered by the presence of continental dust in surrounding regions.
(b) Researchers believe that very low concentrations of dissolved iron are a major factor in limiting biological productivity in remote ocean surface waters.
(c) Studies show that, within the Arctic Basin, iron concentrations are relatively high but vary significantly.
(d) Phytoplankton, the main source of Earth's atmospheric oxygen, require iron to perform various biochemical processes.
(e) The highest iron concentrations are found in regions that have ice floes containing large amounts of surface sediment.

6 
 6. Based on the information in the passage, it can be inferred that which of the following is critical for human life?

(a) aluminum
(b) ice floes
(c) phytoplankton
(d) surface sediment
(e) continental dust

RC Butler 2022  -  Practice Two RC Passages Everyday.   
Passage # 46 Date: 31-Jan-2022
 This question is a part of RC Butler 2022 .  Click here for Details

Source: Knewton GMAT

MayankSingh · Answer

1. It can be inferred from the passage that an example of a detrimental effect in the highlighted text would be-

If you read these lines "Phytoplankton, the basis of freshwater food chains and the source of most of Earth's atmospheric oxygen, require iron for various biochemical processes. Thus, a lack of iron in surface waters has detrimental effects' you get to now that lack of Phytoplankton has direct effect on Oxygen, hence answer A- ) a decrease in the supply of Earth's atmospheric oxygen would be a correct answer.

2. The passage is chiefly concerned with
 the whole passage talks about Iron at different places and why is that case so simply an answer would be (b) presenting possible causes for and effects of variations in iron concentrations in surface waters.

Akarshkhan86 · Answer

Hello  Sajjad1994  can you share the OE of Ques 4? Thanks.

Sajjad1994 · Answer

Explanation

4. It can be inferred from the passage that which of the following would provide the LEAST support for the idea that surface sediment is responsible for increased concentrations of iron in the Arctic Ocean?

Difficulty Level:   700

Explanation

The question asks for the option that would provide the least support for the idea that surface sediment is responsible for increased concentrations of iron in the Arctic Ocean.

Option (e) states: "The observation that there are higher concentrations of aluminum in the Nansen Basin than in the western Arctic."

If there are higher concentrations of aluminum in the Nansen Basin compared to the western Arctic, it actually supports the idea that surface sediment is responsible for increased iron concentrations. The passage mentions that the presence of large amounts of aluminum in the same regions as high iron values bolsters the hypothesis. Therefore, this observation of higher aluminum concentrations in the Nansen Basin would provide support for the idea, rather than being the least supportive.

Answer: E

Prob2303 · Answer

Hello Sajjad,

Can I get a brief explanation of the passage and the OE for Q1 and Q3?

Sajjad1994 · Answer

Explanation

1. It can be inferred from the passage that an example of a detrimental effect in the highlighted text would be

Explanation

(a)  This is the correct answer. The passage states that phytoplankton is the source of most of Earth's atmospheric oxygen and requires iron for various biochemical processes. Therefore, a lack of iron in surface waters could lead to a decrease in the supply of Earth's atmospheric oxygen.

(b)  This is not the correct answer because the passage doesn't suggest a decrease in the significance of phytoplankton. It highlights the detrimental effects of a lack of iron on phytoplankton, indicating the importance of iron for their biochemical processes.

(c)  This is not supported by the passage. The passage discusses the detrimental effects of low iron concentrations on phytoplankton, suggesting a potential decrease in their ability to perform biochemical processes.

(d)  The passage does not provide information about an increase in the dissolution of eolian-transported continental dust. The focus is on the role of iron and its concentrations in surface waters.

(e)  this is not supported by the passage. The passage emphasizes that extremely low concentrations of dissolved iron limit biological productivity in some ocean regions, suggesting that an increase in iron availability would not lead to an increase in biological productivity.

In summary, the correct answer is  (a)  because the passage explicitly mentions the role of phytoplankton in providing Earth's atmospheric oxygen and the detrimental effects of low iron concentrations on this process.

Answer: A

Sajjad1994 · Answer

Explanation

3. The passage suggests which of the following about surface waters of temperate oceans?

Explanation  (a)  The passage does not provide information about the evenness or unevenness of iron distribution in temperate oceans. Therefore, this statement cannot be inferred from the passage.

(b)  The passage does not suggest that iron was absent from temperate oceans before recent advances in analytical methodology. It mentions the dissolution of eolian-transported continental dust as a source of iron in temperate oceans.

(c)  The passage mentions that in temperate and tropical oceans, iron reaches surface waters via the dissolution of eolian-transported continental dust. Therefore, if eolian activity decreased, it could lead to lower concentrations of iron in surface waters.

(d)  This is not supported by the passage. The passage indicates that iron reaches surface waters through the dissolution of eolian-transported continental dust. It doesn't suggest that the direct rise of continental dust to the surface would increase iron concentrations.

(e)  This is not supported by the passage. The passage discusses the hypothesis that ice-rafted sediment is a source of high iron values in the Arctic Ocean but does not suggest that temperate oceans would not contain iron if ice-rafted sediment did not melt.

Answer: C

DangPham9625 · Answer

I think there is something wrong in your explanation. This observation would be the least support for the idea because: the concentration in Nansen Basin is lower than western Arctic (as stated in para 2), while the idea is: more aluminum ==> higher concentration of iron. Correct me if I'm wrong

Despite an abundance of major nutrients in the surface waters of parts

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Despite an abundance of major nutrients in the surface waters of parts

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