Fall leaves

USDA Forest Service

We almost always think of trees as being green, but there is one time of year when their leaves turn a myriad orange, red, yellow and brown: the beautiful and chilly days of fall. Those living in the Eastern or Northern United States come to anticipate the change in color starting in September or October every single year. But what causes the leaves to change color, and why?

Just like many animals that hibernate for the winter, trees experience a unique change during the winter months. During summer, for instance, plants use the process of photosynthesis to transform carbon dioxide found in the air into organic compounds like sugars using energy from the sun. During the winter, however, there is less light to go around, and their ability to create food from the photosynthesis process is limited.

What does that have to do with a leaf’s color? The substance that allows trees to turn carbon dioxide into food (chlorophyll) is also the cause for the leaf’s green sheen. As the photosynthesis process wanes in the colder months due to the lack of sun, so does its greenish hue, allowing other elements present in the leaf to show through. Believe it or not, the yellows and oranges that appear in fall have actually been there all year in the form of nutrients like carotene (also found in carrots). The intense green color of the chlorophyll had simply overshadowed them.

But what about the reds and browns? And what causes the leaves to fall away after they change color?
The bright reds and purples in each leaf come from a strong antioxidant that many trees create on their own because of their protective qualities. The antioxidant helps protect the trees from the sun, lower their freezing levels, and protect them from frost. As winter comes, so does the need for the antioxidant (similar to the way a dog gets more fur during winter to stay warmer).

As for the leaves falling, that is another story. At the base of each leaf, there is a layer of cells that carry food and water from the leaf to the tree during the summer months to keep it fed. In the fall, that layer actually starts to harden, preventing the passage of nutrients. Because of this, the nutrients and waste that previously passed from the leaf into the tree become trapped in the leaf with no fresh water to clean it. Not only does this cause the leaf to turn brown, eventually it causes the cells within it to harden so much that the leaf tears and blows away. Thus the pile of leaves you enjoyed jumping in as a child.

Because each tree, and each leaf, contains a unique amount of nutrients depending on how well-nourished it was over the spring and summer, the way each leaf breaks down during the winter months is also quite different. The result is the unique and complex facet of colors we see in each neighborhood or forest each fall.

Which is the best paraphrase of the last paragraph of this selection?

Fall leaves

USDA Forest Service

We almost always think of trees as being green, but there is one time of year when their leaves turn a myriad orange, red, yellow and brown: the beautiful and chilly days of fall. Those living in the Eastern or Northern United States come to anticipate the change in color starting in September or October every single year. But what causes the leaves to change color, and why?

Just like many animals that hibernate for the winter, trees experience a unique change during the winter months. During summer, for instance, plants use the process of photosynthesis to transform carbon dioxide found in the air into organic compounds like sugars using energy from the sun. During the winter, however, there is less light to go around, and their ability to create food from the photosynthesis process is limited.

What does that have to do with a leaf’s color? The substance that allows trees to turn carbon dioxide into food (chlorophyll) is also the cause for the leaf’s green sheen. As the photosynthesis process wanes in the colder months due to the lack of sun, so does its greenish hue, allowing other elements present in the leaf to show through. Believe it or not, the yellows and oranges that appear in fall have actually been there all year in the form of nutrients like carotene (also found in carrots). The intense green color of the chlorophyll had simply overshadowed them.

But what about the reds and browns? And what causes the leaves to fall away after they change color?
The bright reds and purples in each leaf come from a strong antioxidant that many trees create on their own because of their protective qualities. The antioxidant helps protect the trees from the sun, lower their freezing levels, and protect them from frost. As winter comes, so does the need for the antioxidant (similar to the way a dog gets more fur during winter to stay warmer).

As for the leaves falling, that is another story. At the base of each leaf, there is a layer of cells that carry food and water from the leaf to the tree during the summer months to keep it fed. In the fall, that layer actually starts to harden, preventing the passage of nutrients. Because of this, the nutrients and waste that previously passed from the leaf into the tree become trapped in the leaf with no fresh water to clean it. Not only does this cause the leaf to turn brown, eventually it causes the cells within it to harden so much that the leaf tears and blows away. Thus the pile of leaves you enjoyed jumping in as a child.

Because each tree, and each leaf, contains a unique amount of nutrients depending on how well-nourished it was over the spring and summer, the way each leaf breaks down during the winter months is also quite different. The result is the unique and complex facet of colors we see in each neighborhood or forest each fall.

If a student wanted to use a direct quote from this article in an essay, he would NOT need to ...

Bushmen

With so much technology around us each day, it is hard to imagine that anyone in the world would live without television, let alone a cell phone or radio. Still, there are a few cultures that maintain an extremely primitive lifestyle, nearly untouched by the modern world. One of those is commonly known as the Bushmen of Kalahari.

The Bushmen, also known as the “Basarwa” or “San” are found throughout southern Africa in regions of the Kalahari Desert. Nomadic hunters and gatherers by nature, they roam the region living in small kinship groups and, relatively isolated from the rest of society, have developed an extremely unique culture not otherwise seen or understood by modern man.

Unlike English, which is built on a complex system of sounds and letters, the Bushmen speak an extremely unique language made exclusively of clicking sounds. The sounds are created with a sucking action from the tongue, and even the click language itself can vary widely from tribe to tribe, making it extremely difficult to communicate with non-Bush people.

In addition to language, the Bushmen have a very different way of living. Similar to Eskimos, groups of Bushmen will live in “kinship” societies. Led by their elders, they travel together, with women in the group gathering food while men hunt for it. Children, on the other hand, have no duties other than playing. In fact, leisure is an extremely important part of the Bushmen society. Dance, music and humor are essential, with a focus on family rather than technology or development. Because of this, some people associate the Bush culture with a backward kind of living or low status.

Because of the increased speed of advancement and urban development, the Bushmen culture is in danger. Some have already been forced to switch from hunting to farming due to modernization programs in their countries. Others have been forced to move to certain areas of their countries so that modernization can continue to occur there. With so much development, it’s clear that though the Bushmen culture is very rich, it is also in danger of extinction. It is unclear how long the Bush culture will continue.

What sentence best paraphrases the fourth paragraph of this selection?