Reading ComprehensionDifficulty: Easy

PT124 S4 P4 Q20 Explanation

Cyclamen Mites

A free, expert breakdown of this official LSAT Reading Comprehension question.

TopicsMain PointScience

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Passage

Sometimes there is no more effective means of controlling an agricultural pest than giving free rein to its natural predators. A case in point is the cyclamen mite, a pest whose population can be effectively controlled by a predatory mite of the genus Typhlodromus. Cyclamen mites infest strawberry plants; they typically establish year, rapidly subdue the cyclamen mite populations, and keep them from reaching significantly damaging levels.

Typhlodromus owes its effectiveness as a predator to several factors in addition to its voracious appetite. Its population can increase as rapidly as that of its prey. Both species reproduce by parthenogenesis—a mode of reproduction in which unfertilized eggs develop into fertile females. Cyclamen mites lay three eggs per day over the the seasonal rises and falls of its prey, are common among predators that control prey populations.

Greenhouse experiments have verified the importance of Typhlodromus predation for keeping cyclamen mites in check. One group of strawberry plants was stocked with both predator and prey mites; a second group was kept predator-free by regular application of parathion, an insecticide that kills the predatory species but does not affect the cyclamen with Typhlodromus, but their infestation attained significantly damaging proportions on predator-free plants.

Applying parathion in this instance is a clear case in which using a pesticide would do far more harm than good to an agricultural enterprise. The results were similar in field plantings of strawberries, where cyclamen mites also reached damaging levels when predators were eliminated by parathion, but they did not attain were about 25 times more abundant in the absence of predators than in their presence.

What this question is testing

Main Point

Your task

Capture the passage's overall primary point — the claim everything else supports.

Common trap

Answers that are true but too narrow (a single paragraph) or too broad (beyond the passage's scope).

Winning move

Summarize the whole passage in one sentence first, then match it to a choice.

Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.

The question
20.

Which one of the following most accurately expresses the main point of

Answer choices

  1. Too Strong: "most effectively"5% picked this

    Control of agricultural pests is most effectively and safely accomplished without the use of pesticides, because these pesticides can kill predators

    This is in the right direction, but the extreme language is a giveaway that it's wrong. Our most valuable sentences are the first two sentences, which say "Sometimes the natural predator is better than pesticides".

  2. Too Strong: "essential" Too Narrow / Assumption1% picked this

    Experimental verification is essential in demonstrating the effectiveness of natural controls

    The extreme word essential is a quick reason to consider this unlikely. Its emphasis on experimental verification is definitely not the main point. This just sounds an assumption the author may have in presenting the 3rd and 4th paragraphs. The main point should sound like the general claim in the first sentence or like the application-of-the-general claim in the second sentence.

  3. Correct89% picked this

    The relationship between Typhlodromus and cyclamen mites demonstrates how natural predation can keep a population of

    Why this is right

    This nicely synthesizes the Example (cycla / typhlo) with the General (natural predation can be best way to control pest).

    Skill tested: Main Point · how this choice captures the passage's function is the move to repeat next time.

  4. Too Strong: "essential"4% picked this

    Predation by Typhlodromus is essential for the control of cyclamen mite populations

    The author is never making such an extreme case that Typhlodromus is necessary, just that it's super effective and probably better to rely on this natural predator when it comes to getting cyclamen off strawberry plants.

  5. Too Narrow1% picked this

    Similarity in mode and timing of reproduction is what enables Typhlodromus effectively to control populations of cyclamen mites

    Yes, this is established in the 2nd paragraph, but "the reason T is an effective way to control C" is not the main point. The main point is a more general point about how natural predators can sometimes be are best form of crop control.

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