Reading Comprehension

PT2 · S1 · P3 · Q18 Water Bugs

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Three basic adaptive responses—regulatory, acclimatory, and developmental—may occur in organisms as they react to changing environmental conditions.

Topic

How organisms—specifically water bugs—adapt to environmental changes, with a focus on reversible and irreversible responses.

Framework

Theme / Example

Main Point

Organisms can adapt to environmental changes through regulatory, acclimatory, and developmental responses; in water bugs, the developmental response determining wing type is an environmentally driven, permanent adjustment rather than a genetic one. *The Most Valuable Sentence appears in the third paragraph: *

P1: Types of Adaptive Responses

This paragraph introduces the three major types of adaptive responses: regulatory (quick, reversible physiological adjustments), acclimatory (slower, reversible structural changes), and developmental (usually permanent, fixed during development).

P2: Developmental Responses in Water Bugs

Here, the passage zooms in on developmental responses—using water bugs as an example—to explain how different generations have different wing types based on their seasonal needs. The summer generation shows two forms (some with normal wings, some with reduced wings), while the overwintering generation always has full wings for dispersing. This dimorphism is a strategy for survival given environmental uncertainties.

P3: Environmental Determination of Wing Type

This paragraph explains that the wing type variation in water bugs is not genetic, but determined by the temperature during egg development—cold temperatures lead to reduced wings, while warm temperatures lead to full wings. All overwintering bugs come from eggs formed in warm temps, ensuring full wings for migration; experimental evidence supports that temperature, not genetics, decides wing form.

18.

It can be inferred from the passage that which one of the following is an example of a regulatory response?

thickening of the plumage of
Weaker Match
It's hard to tell whether this is a rapid increase in plumage (i.e. feathers). Since it's related to autumn, it sounds like it could be relatively slow and seasonal.
6% picked this
Correct
increase in pulse rate during
Why this is right
This answer choice doesn't explicitly say whether the increase in pulse rate (a physiological process) is rapid, but our common sense tells us that vigorous exercise isn't a sustained type of situation. You go do a cardio class and your pulse rate increases? That sounds like a pretty rapid increase (the same hour as the stimulus).
Skill tested: Application · how this choice captures the passage's function is the move to repeat next time.
85% picked this
gradual darkening of the skin
Bad Match
We're explicitly told that this isn't a rapid response; it's gradual.
2% picked this
gradual enlargement of muscles as
Bad Match
We're explicitly told that this isn't a rapid response; it's gradual.
2% picked this
development of a heavy fat
Weaker Match
Like (A), it's not clear whether this is slow or rapid, but like (A) because it's related to a season, it's more likely that it would be gradual. If we think about "reacting to autumn" (A), "prepping for hibernation" (E), or "reacting to vigorous exercise" (B), it seems like vigorous exercise takes place within a day, whereas (A) and (E) might take place over weeks or months.
5% picked this

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