Cultivation of a single crop on a given tract of land leads eventually

Question

New Project RC Butler 2019  -  Practice 2 RC Passages Everyday   
Passage # 124, Date : 03-APR-2019
 This post is a part of New Project RC Butler 2019 .  Click here for Details

Cultivation of a single crop on a given tract of land leads eventually to decreased yields. One reason for this is that harmful bacterial phytopathogens, organisms parasitic on plant hosts, increase in the soil surrounding plant roots. The problem can be cured by crop rotation, denying the pathogens a suitable host for a period of time. However, even if crops are not rotated, the severity of diseases brought on by such phytopathogens often decreases after a number of years as the microbial population of the soil changes and the soil becomes “suppressive” to those diseases. While there may be many reasons for this phenomenon, it is clear that levels of certain bacteria, such as Pseudomonas fluorescens, a bacterium antagonistic to a number of harmful phytopathogens, are greater in suppressive than in nonsuppressive soil. This suggests that the presence of such bacteria suppresses phytopathogens. There is now considerable experimental support for this view. Wheat yield increases of 27 percent have been obtained in field trials by treatment of wheat seeds with fluorescent pseudomonads. Similar treatment of sugar beets, cotton, and potatoes has had similar results.

These improvements in crop yields through the application of Pseudomonas fluorescens suggest that agriculture could benefit from the use of bacteria genetically altered for specific purposes. For example, a form of phytopathogen altered to remove its harmful properties could be released into the environment in quantities favorable to its competing with and eventually excluding the harmful normal strain. Some experiments suggest that deliberately releasing altered nonpathogenic Pseudomonas syringae could crowd out the nonaltered variety that causes frost damage. Opponents of such research have objected that the deliberate and large-scale release of genetically altered bacteria might have deleterious results. Proponents, on the other hand, argue that this particular strain is altered only by the removal of the gene responsible for the strain’s propensity to cause frost damage, thereby rendering it safer than the phytopathogen from which it was derived.

Some proponents have gone further and suggest that genetic alteration techniques could create organisms with totally new combinations of desirable traits not found in nature. For example, genes responsible for production of insecticidal compounds have been transposed from other bacteria into pseudomonads that colonize corn roots. Experiments of this kind are difficult and require great care: such bacteria are developed in highly artificial environments and may not compete well with natural soil bacteria. Nevertheless, proponents contend that the prospects for improved agriculture through such methods seem excellent. These prospects lead many to hope that current efforts to assess the risks of deliberate release of altered microorganisms will successfully answer the concerns of opponents and create a climate in which such research can go forward without undue impediment.   1 
 1. Which one of the following best summarizes the main idea of the passage?

(A) Recent field experiments with genetically altered Pseudomonas bacteria have shown that releasing genetically altered bacteria into the environment would not involve any significant danger.
(B) Encouraged by current research, advocates of agricultural use of genetically altered bacteria are optimistic that such use will eventually result in improved agriculture, though opponents remain wary.
(C) Current research indicates that adding genetically altered Pseudomonas syringae bacteria to the soil surrounding crop plant roots will have many beneficial effects, such as the prevention of frost damage in certain crops.
(D) Genetic alteration of a number of harmful phytopathogens has been advocated by many researchers who contend that these techniques will eventually replace such outdated methods as crop rotation.
(E) Genetic alteration of bacteria has been successful in highly artificial laboratory conditions, but opponents of such research have argued that these techniques are unlikely to produce organisms that are able to survive in natural environments.

2 
 2. The author discusses naturally occurring Pseudomonas fluorescens bacteria in the first paragraph primarily in order to do which one of the following?

(A) prove that increases in the level of such bacteria in the soil are the sole cause of soil suppressivity
(B) explain why yields increased after wheat fields were sprayed with altered Pseudomonas fluorescens bacteria
(C) detail the chemical processes that such bacteria use to suppress organisms parasitic to crop plants, such as wheat, sugar beets, and potatoes
(D) provide background information to support the argument that research into the agricultural use of genetically altered bacteria would be fruitful
(E) argue that crop rotation is unnecessary, since diseases brought on by phytopathogens diminish in severity and eventually disappear on their own

3 
 3. It can be inferred from the author’s discussion of Pseudomonas fluorescens bacteria that which one of the following would be true of crops impervious to parasitical organisms?

(A) Pseudomonas fluorescens bacteria would be absent from the soil surrounding their roots.
(B) They would crowd out and eventually exclude other crop plants if their growth were not carefully regulated.
(C) Their yield would not be likely to be improved by adding Pseudomonas fluorescens bacteria to the soil.
(D) They would mature more quickly than crop plants that were susceptible to parasitical organisms.
(E) Levels of phytopathogenic bacteria in the soil surrounding their roots would be higher compared with other crop plants.

4 
 4. It can be inferred from the passage that crop rotation can increase yields in part because

(A) moving crop plants around makes them hardier and more resistant to disease
(B) the number of Pseudomonas fluorescens bacteria in the soil usually increases when crops are rotated
(C) the roots of many crop plants produce compounds that are antagonistic to phytopathogens harmful to other crop plants
(D) the presence of phytopathogenic bacteria is responsible for the majority of plant diseases
(E) phytopathogens typically attack some plant species but find other species to be unsuitable hosts

5 
 5. According to the passage, proponents of the use of genetically altered bacteria in agriculture argue that which one of the following is true of the altered bacteria used in the frost-damage experiments?

(A) The altered bacteria had a genetic constitution differing from that of the normal strain only in that the altered variety had one less gene.
(B) Although the altered bacteria competed effectively with the nonaltered strain in the laboratory, they were not as viable in natural environments.
(C) The altered bacteria were much safer and more effective than the naturally occurring Pseudomonas fluorescens bacteria used in earlier experiments.
(D) The altered bacteria were antagonistic to several types of naturally occurring phytopathogens in the soil surrounding the roots of frost-damaged crops.
(E) The altered bacteria were released into the environment in numbers sufficient to guarantee the validity of experimental results.

6 
 6. Which one of the following, if true, would most seriously weaken the proponents’ argument regarding the safety of using altered Pseudomonas syringae bacteria to control frost damage?

(A) Pseudomonas syringae bacteria are primitive and have a simple genetic constitution.
(B) The altered bacteria are derived from a strain that is parasitic to plants and can cause damage to crops.
(C) Current genetic-engineering techniques permit the large-scale commercial production of such bacteria.
(D) Often genes whose presence is responsible for one harmful characteristic must be present in order to prevent other harmful characteristics.
(E) The frost-damage experiments with Pseudomonas syringae bacteria indicate that the altered variety would only replace the normal strain if released in sufficient numbers.

Source:   LSAT Official PrepTest 7   ( February 1993 ) 
 Difficulty Level:   650

nitya34 · Accepted Answer

here you go

19. According to the passage, proponents of the use of genetically altered bacteria in agriculture argue that which one of the following is true of the altered bacteria used in the frost-damage experiments?
(A) The altered bacteria had a genetic constitution differing from that of the normal strain only in that the altered variety had one less gene.
(B) Although the altered bacteria competed effectively with the nonaltered strain in the laboratory, they were not as viable in natural environments.
(C) The altered bacteria were much safer and more effective than the naturally occurring Pseudomonas fluorescens bacteria used in earlier experiments.
(D) The altered bacteria were antagonistic to several types of naturally occurring phytopathogens in the soil surrounding the roots of frost-damaged crops.
(E) The altered bacteria were released into the environment in numbers sufficient to guarantee the validity of experimental results.

19. (A)
 In this one, we’re interested in what proponents of genetic engineering think about the altered bacteria used in the frost-damage experiments, and that’s outlined in lines 41-45.
Line 41, specifically (“Proponents, on the other hand, argue that . . .”), announces that this is where the answer is likely to be found. The proponents assert that genetically altered bacteria used in these experiments differ from the naturally occurring bacteria only in that one gene—the one that causes frost damage—has been removed from the altered bacteria, which brings us to choice (A). 
20. Which one of the following, if true, would most seriously weaken the proponents’ argument regarding the safety of using altered Pseudomonas syringae bacteria to control frost damage?
(A) Pseudomonas syringae bacteria are primitive and have a simple genetic constitution.
(B) The altered bacteria are derived from a strain that is parasitic to plants and can cause damage to crops.
(C) Current genetic-engineering techniques permit the large-scale commercial production of such bacteria.
(D) Often genes whose presence is responsible for one harmful characteristic must be present in order to prevent other harmful characteristics.
(E) The frost-damage experiments with Pseudomonas syringae bacteria indicate that the altered variety would only replace the normal strain if released in sufficient numbers.
20. (D)
 Again we’re concerned with the frost-damage issue, but this time we’re asked what, if true, would weaken the proponents’ argument. We just reviewed their argument for the sake of the previous question, so it should be fresh in our minds: These proponents claim that the new bacteria, which is the old minus the one harmful gene, limits frost damage without causing any harmful effects. Well, if it were true that the deletion of one gene could indeed cause harmful effects, this argument would be weakened. (D) leads us in that direction: If the gene removed from the original pathogenic bacteria may very well be responsible for
protecting the crop in other ways, then removing this gene may thus endanger the crop and therefore warrant the opponents’ fear of “deleterious results.”

Kratul412 · Answer

Can someone explain Question no 4? Asnwer

Posted from my mobile device

Sajjad1994 · Answer

Explanation

4. It can be inferred from the passage that crop rotation can increase yields in part because

Difficulty Level:   650

Explanation

As we know by now, crop rotation is discussed at the beginning of the passage, so let’s look there. In  lines 5-6 , the author says that crop rotation cuts down on the problem posed by phytopathogens by denying them a  “suitable host.”  This is how crop rotation can cure the problem of decreased yield. Working straight from the language, plants that  “deny phytopathogens a suitable host”  must be  “UNsuitable hosts.”  This suggests that not every phytopathogen can attach to every host, which in turn means that specific phytopathogens must attack specific kinds of plants. All of this points directly to  choice (E).

(A)  According to the passage, crop rotation seems to help crops not by making them stronger, but rather by making their environment less harmful.

(B)  If anything,  lines 6-14  seem to suggest that the number of Pseudomonas fluorescens bacteria in the soil increases when crops are not rotated. What happens to their number when crops are rotated is anyone’s guess.

(C)  Compounds produced by the roots of crop plants are beyond the scope of the passage. Nothing allows us to infer what kind of compounds such roots might produce, no less what connection this might have to the benefits of crop rotation.

(D)  Although we know that phytopathogenic bacteria cause crop disease, there’s no information in the passage which would indicate to us that they’re responsible for most crop diseases. More importantly, like  (C) , even if we could agree to this, what connection does this have to the way in which crop rotation increases yield?

Answer: E

This is not Official explanation rather belongs to Kaplan LSAT

mohitasinghal · Answer

In question 1 why is option D incorrect.. i marked d because the passage begins with the introduction of crop rotation but goes on to describe the pros and cons of genetic alteration as an alternative..please explain

Sajjad1994 · Answer

(D)  Crop rotation is never characterized as  “outdated,”  nor is there any suggestion of getting rid of it. It is merely mentioned in the beginning as background information. This passage isn’t about the possible effects of genetic research on crop rotation; it’s about a debate over the efficacy of using genetic engineering to boost agriculture, a different issue.

Hope it helps

Sipun6000 · Answer

Can anyone explain question no. 6?

Posted from my mobile device

Sajjad1994 · Answer

Explanation

6. Which one of the following, if true, would most seriously weaken the proponents’ argument regarding the safety of using altered Pseudomonas syringae bacteria to control frost damage?

Difficulty Level:   700

Explanation

Again we’re concerned with the frost-damage issue, but this time we’re asked what, if true, would weaken the proponents’ argument. We just reviewed their argument for the sake of the previous question, so it should be fresh in our minds: These proponents claim that the new bacteria, which is the old minus the one harmful gene, limits frost damage without causing any harmful effects. Well, if it were true that the deletion of one gene could indeed cause harmful effects, this argument would be weakened. (D) leads us in that direction: If the gene removed from the original pathogenic bacteria may very well be responsible for
protecting the crop in other ways, then removing this gene may thus endanger the crop and therefore warrant the opponents’ fear of “deleterious results.”

(A)  Primitive and simple? So what? This has no bearing on the argument that the altered bacteria is safer because it doesn’t contain the gene that causes frost damage.

(B)  is entirely consistent with the proponents’ argument, so it obviously doesn’t weaken their argument. They never claimed that the altered bacteria derived from anything but a harmful phytopathogen. Indeed, their claim is that they’re turning a harmful bacterium into a beneficial one by altering its genetic structure.

(C)  Commercial production of genetically altered bacteria is irrelevant to the issue of the safety of such bacteria, which is after all the cornerstone of the proponents’ argument.

(E) Like (C) , the info in  (E) —how the altered variety works most efficiently—doesn’t address the safety issue. Instead, it speaks to the effectiveness of the altered bacteria, a different issue entirely.

Answer: D

This is not Official explanation rather belongs to Kaplan LSAT

medhamahrishi31 · Answer

SajjadAhmad  
Please explain Q2 and Q3 of this passage

Sajjad1994 · Answer

Explanation

2. The author discusses naturally occurring Pseudomonas fluorescens bacteria in the first paragraph primarily in order to do which one of the following?

Difficulty Level:   650

Explanation

Next up is another  “function of a detail”  question. Locate the detail and try to understand it in its proper context. The stem directs us to the  first para , where Pseudomonas fluorescens appears in  line 15 . Here we find out that this bacterium seems to suppress harmful phytopathogens, thereby contributing to improved crop yields. In the first sentence of the  second paragraph , the author cites this fact— “These improvements in crop yields. . .” —in support of the belief that putting genetically altered bacteria into the soil might be a good thing for agriculture. In other words, the author uses this example to show how the position advocated by the proponents regarding genetically altered bacteria may have evolved.  Choice (D)  makes this point, employing slightly different language.

(A)  contradicts information in the passage. In  lines 13-14 , the author specifically says that there may be a number of reasons, not just one, for soil suppressivity.

(B)  Even if the  “treatment of wheat seeds”  is the same thing as  “spraying wheat fields,”  there’s still no explanation as to why the yields increased, only that they did increase.

(C)  The passage never details any  “chemical processes.”  Even if it had, that’s not why the author discussed Pseudomonas fluorescens.

(E)  The author never says or implies that crop rotation is unnecessary (see first bullet point below). Moreover, the author never says or implies that phytopathogens  “eventually
disappear on their own” ; this is an exaggeration.

Answer: D

3. It can be inferred from the author’s discussion of Pseudomonas fluorescens bacteria that which one of the following would be true of crops impervious to parasitical organisms?

Difficulty Level:   700

Explanation

According to  line 4, “phytopathogens”  are parasitic. So crops  “impervious”  to parasites cannot be harmed by phytopathogens. Such crops will therefore not be helped by the addition of Pseudomonas fluorescens to the soil around them; after all, the reason for adding this bacterium to the soil in the first place is to protect crops from harmful phytopathogens. This benefit would be absent for crops that are impervious to parasites, which points to  choice (C).

(A)  There’s nothing in the passage which says or suggests that the presence or absence of Pseudomonas fluorescens in the soil around crops is in any way connected to the susceptibility of crops to phytopathogens. In other words, Pseudomonas fluorescens may be present whether or not there are parasites for it to act against.

(B) and (D)  The passage doesn’t provide us with any facts about these crops mentioned in the stem—those which are resistant to phytopathogens—so we can’t infer anything about their growth patterns or their effects on other crops.

(E) ’s out for much the same reason as  (A) : All we know about  “impervious”  crops is that they’re immune to phytopathogenic bacteria. We can’t infer from this how much of such bacteria surrounds these plants in comparison to other crops. There may be a lot, there may be a little; all we know for sure is that no matter how much surrounds the roots of these plants, it has no detrimental effect.

Answer: E

This is not Official explanation rather belongs to Kaplan LSAT

Sajjad1994 · Answer

Explanation

5. According to the passage, proponents of the use of genetically altered bacteria in agriculture argue that which one of the following is true of the altered bacteria used in the frost-damage experiments?

Difficulty Level:   700

Explanation

In this one, we’re interested in what proponents of genetic engineering think about the altered bacteria used in the frost-damage experiments, and that’s outlined in lines 41-45.
Line 41, specifically (“Proponents, on the other hand, argue that . . .”), announces that this is where the answer is likely to be found. The proponents assert that genetically altered bacteria used in these experiments differ from the naturally occurring bacteria only in that one gene—the one that causes frost damage—has been removed from the altered bacteria, which brings us to choice (A).

(B)  distorts a detail brought up in  lines: "Nevertheless, proponents contend that the prospects for improved agriculture through such methods seem excellent"  which, in any case, has nothing to do with the frost-damage experiments.

(C)  Those who favor the use of altered bacteria never make any comparison between the safety and effectiveness of the altered bacteria used in the frost damage experiments and naturally occurring Pseudomonas fluorescens. They merely claim that the altered bacteria in these experiments is safer than the phytopathogenic bacterium from which it was derived, Pseudomonas syringae.

(D)  Proponents claim that the altered bacteria will attack one type of phytopathogen, the one that causes frost damage to crops; nowhere do they say or imply that the altered bacteria fought against  “several types of naturally occurring phytopathogens.”

(E)  This claim is never made by the supporters of genetic engineering; in fact, they never discuss anything regarding the number of bacteria released. If anything, it is the opponents who speak of  “large-scale release”  of genetically altered bacteria, and not in the specific context of the frost-damage experiments at that.

Answer: A

This is not Official explanation rather belongs to Kaplan LSAT

HeatherRMurray · Answer

Are there only 6 questions? I see there is a #19 and #20 at the top of this tread. Where did these questions come from?

bM22 · Answer

Hey  HeatherRMurray ,

19th and 20th Questions are nothing but 5th and 6th Questions of the passage. Since the passage was posted long back, the question numbers were similar to how they were in the official LSAT Prep, but later formatted to 1 to 6 sequence.

Thanks.

JainAnuj · Answer

can someone please explain me, why did we choose Option C for question no 3

Cultivation of a single crop on a given tract of land leads eventually

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GMAT Reading Comprehension (RC) Questions

Cultivation of a single crop on a given tract of land leads eventually

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