Reading Comprehension

PT124 · S4 · P4 · Q21 Cyclamen Mites

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Sometimes there is no more effective means of controlling an agricultural pest than giving free rein to its natural predators.

Central Topic

Controlling unwanted crop pests with natural predators vs. pesticides

Framework

Theme / Example

Main Point

Sometimes you'd get better results managing a crop pest population with a natural predator than with a pesticide, as is the case with cyclamen mites and their predator, Typhlodromus.

Passage Map

(P1) General idea. Introduction to specific example -- Sometimes letting natural predator control a crop pest is the best way. A case in point is cyclamen/tyhplo. (P2) Reasons typhlo is an effective way to control cyclamen (P3) Experimental support for effectiveness of typhlo (P4) Practical, in the field, support for effectiveness of typhlo

Other Commentary

On physical science passages that have visually challenging terms (like cyclamen, typhlodromus, parathion), it is very helpful for understanding and retention to re-brand those in much simpler terms.

As we pause to self-summarize, we want to be saying things like,

The second sentence of the passage reveals the purpose / main point of the passage, with the rhetorical phrase a case in point.

Just like when we see "for example", when we see "a case in point" we are becoming aware that the author cares enough about the previous idea to try to support it and flesh it out.

When you find a framing idea that the author wants to support, you should pause and re-read that framing idea until you've self-summarized it in easy language that you can understand and remember.

21.

Based on the passage, the author would probably hold that which one of the following principles is fundamental to long-term predatory control of agricultural pests?

  1. The reproduction of the predator

    Reversal

    In the case of T's and C's, the prey's population surges first, and then T swoops in and eats them.

    23% picked this

  2. The effectiveness of the predatory

    Unsupported

    This is pulling details from the 3rd and 4th paragraphs (greenhouse and field applications), but we can tell that the keywords from the question stem are connecting to the last sentence of the 2nd sentence. We have no textual way to attach the 3rd and 4th paragraph ideas to the concept of "fundamental to long-term control". The textual support for fundamental characteristics of long-term control has to come from the "features" referred to in that end of 2nd paragraph sentence.

    5% picked this

  3. The prey population should be

    Reversal

    In the story of the C's and T's, the predator survives in times of low prey population, when the latter have dwindled during winter.

    6% picked this

  4. Correct

    The predator population's level of

    Why this is right

    This describes the dynamic population levels we heard about in the 2nd paragraph. Middle of that paragraph describes "seasonal synchrony of T reproduction with the growth of C population and ability to survive at low C density".

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

    62% picked this

  5. The predator population should be

    Too Strong: "only" Unsupported

    This idea doesn't make much common sense. The predator and the pesticide have the same goal -- kill the prey. If a farmer wanted to take advantage of both the natural predator and a pesticide, she would want the pesticide to only kill the prey, so that the predator can also kill the prey. The pesticide parathion was an example of a pesticide that only killed the predator population. It was discussed because it was used in an experiment that would see how the prey would fare if we used a pesticide to kill off the predator.

    4% picked this

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