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Test: Common Core: 4th Grade English Language Arts
Passage and table adapted from "Why Leaves Change Color" on "Northeastern Area," a website by the USDA Forest Service. <https://www.na.fs.fed.us/fhp/pubs/leaves/leaves.shtm>.
There are two main types of trees: coniferous trees and deciduous trees. Coniferous trees have small, needle-like leaves. They keep these leaves all year. One example of a coniferous tree is a pine tree, which has green needles during all seasons. In contrast, deciduous trees lose their leaves every autumn. Before these leaves drop and blow away, they change from green to colors like red, orange, yellow, and brown.
Have you ever wondered why deciduous leaves change color in the fall? This color change is caused by a chemical process in the cells of tree leaves.
Green leaves are green because they contain a green molecule, chlorophyll. This is a very important molecule in the natural world. Leaves use this molecule to turn carbon dioxide, sunlight, and water into sugar and oxygen in a process called “photosynthesis.” So, chlorophyll lets the plant store energy as sugar, which it can use as food. It also lets the plant provide food for anything that eats it, like a cow, a bird, or even a human!
So, what does chlorophyll, a green molecule, have to do with autumn leaf colors? Deciduous leaves also contain molecules of other colors, but the chlorophyll in the leaves covers them up in the summer. In the fall, deciduous trees stop making chlorophyll. Eventually there is no more chlorophyll in their leaves. The colors of the other molecules show through. The colors of these other molecules are the colors we see in autumn leaves. The next time you see colorful leaves in the fall, you’ll know more about the chemistry at work!
| 1. | Which of the following statements best states the main idea of this passage? |
Photosynthesis is a process that is crucial to nature.
Deciduous trees' leaves are green in the summer because of chlorophyll, a green molecule.
Deciduous trees' leaves change color in the fall because a balance of colorful molecules in them changes.
Coniferous trees are very different from deciduous trees.
