Difficulty: Hard

Average Score: 33%

A turning leaf stays green at first, then reveals splotches of yellow and red as chlorophyll gradually breaks down. Dark green seems to stay longest in the veins, outlining and defining them. During the summer, chlorophyll breaks down in the heat and light, but it is also being steadily replaced. In the fall, on the other hand, no new pigment is produced, and so we notice the other colors that were always there, although chlorophyll's shocking green hid them from view. With their camouflage gone, we see these colors for the first time all year, and marvel, but they were always there, hidden like a vivid secret beneath the hot glowing greens of summer.

According to the passage, which of the following most directly causes leaves to change their color in the fall?

Rationale

New chlorophyll no longer being produced.

The passage explains that the change in leaf color during the fall is primarily due to the cessation of chlorophyll production, which allows other pigments to become visible. When chlorophyll fades, the greens of leaves diminish, revealing the yellows, oranges, and reds that were previously masked.

A (Chlorophyll in the leaves beginning to break down then) YOUR ANSWER

While chlorophyll breakdown is part of the color change process, it is not the direct cause. The critical factor leading to the change in color is not merely the breakdown of chlorophyll but rather the lack of its production, which prevents fresh green chlorophyll from masking the other pigments.

B (Heat and light causing new pigments to be produced) YOUR ANSWER

This option suggests that environmental factors like heat and light are responsible for producing new pigments. However, the passage does not indicate that new pigments are created; rather, it highlights that the existing pigments become visible due to the absence of chlorophyll.

C (Existing pigments becoming more uniform) YOUR ANSWER

The concept of pigments becoming more uniform is not supported in the passage. The change in color is due to the relative visibility of existing pigments rather than any uniformity among them. As chlorophyll fades, the diversity of colors from other pigments becomes more pronounced.

D (New chlorophyll no longer being produced) CORRECT

The cessation of new chlorophyll production is the direct cause of the change in leaf color. As chlorophyll levels drop, the vibrant greens fade, making way for the other pigments that were always present but hidden.

Conclusion

The passage illustrates that the leaves' color change in the fall is directly linked to the lack of new chlorophyll production. This leads to the visibility of other pigments, marking a significant transformation in leaf appearance. Understanding this process emphasizes the importance of chlorophyll in maintaining the green color and highlights how changes in its production can drastically affect the visual landscape of autumn foliage.

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