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Difficulty: EasyPrimary Purpose of the Whole Text

During the spring and summer, leaves appear green due to the high concentration of chlorophyll, the pigment responsible for photosynthesis. As autumn approaches and daylight hours decrease, trees begin to shut down their food-making process. The chlorophyll breaks down, causing the green color to fade from the leaves. This breakdown reveals other pigments, such as carotenoids, which produce yellow, orange, and brown hues and have been present in the leaves all along. While chlorophyll dominates the warm months, these underlying pigments finally become visible in the fall, transforming the forest canopy.

Which choice best states the main purpose of the text?

  1. To describe the biological process that leads to the appearance of yellow and orange colors in autumn leaves.Answer
  2. B
    To explain the chemical structure and function of chlorophyll in photosynthesis during the spring and summer.
  3. C
    To argue that carotenoids are newly synthesized by trees as a protective response to decreasing autumn temperatures.
  4. D
    To discuss the overall seasonal lifecycle and survival strategies of temperate forest trees throughout the year.

Answer

To describe the biological process that leads to the appearance of yellow and orange colors in autumn leaves.
The correct option accurately states the primary purpose of the text, which is to explain the biological mechanism behind the change in leaf color during autumn. The passage describes how the breakdown of chlorophyll, triggered by decreasing daylight hours, reveals underlying pigments like carotenoids that produce yellow and orange hues.

Step-by-Step Solution

1
Identify the main topic introduced at the start of the passage and trace how it is developed.
The passage starts by describing green leaves containing chlorophyll in spring and summer, then explains how a decrease in daylight hours during autumn triggers chlorophyll breakdown, revealing other pigments.
Understanding the transition from summer green to autumn colors helps pinpoint the primary focus of the passage.
2
Summarize the overarching goal of the passage.
The text explains the mechanism behind the changing of leaf colors in the fall.
This summary can be compared against the choices to identify the option that encompasses this primary objective.
3
Evaluate the choices to select the one that matches the summary of the whole text and eliminate incorrect choices.
The option stating the purpose is to describe the biological process that leads to the appearance of yellow and orange colors in autumn leaves matches the summary. The other choices are too narrow, too broad, or factually incorrect.
This step verifies the correct choice while confirming why the distractors are wrong.

Key Concept

Identifying the primary purpose of the whole text requires selecting an option that summarizes the author's primary objective across the entire passage rather than focusing on secondary details or overly broad generalizations.
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Topics

Primary Purpose of the Whole Text

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