Passage 2
Trees are so common arid quiet that we pay them little mind.
What, for instance, should we answer when asked to name the biggest living thing
Earth has ever seen Dinosaurs Blue whales No, the largest sequoias in
northern California weigh more than six blue whales. The tallest redwoods
and Australian eucalyptus trees tower more than 300 feet high, three times the
length of the greatest dinosaur. (71) Some
bristlecone pine trees in the American West are more than 4, 000 years old,
seedlings at the time the Egyptians were building the Pyramids.
Trees sustain our lives and our planet in a thousand practical ways. This
morning at breakfast—in your wood-framed house, on your wooden kitchen table—you
might have enjoyed orange juice or a grapefruit. Both come to use from trees.
Over your French toast you may have sprinkled cinnamon and nutmeg, the powdered
bark and nuts of tropical trees. That quart of maple syrup on your table was
boiled down from roughly 10 gallons of sap from a sugar-maple tree.
(72) Do you like chocolate, almonds, cola beverages.’ Cocoa
beans, almonds and kola nuts are tree products. Frees do more than
mule life pleasant; they make life possible. Trees get water through their roots
and, primarily through their leaves, they draw carbon dioxide from the air.
Then, with the action of sunlight on cells containing chlorophyll and other
materials, chemical reactions occur, and oxygen is released. (73)
Photosynthesis also produces glucose, a type of sugar.
Trees convert some of the glucose to starch, which they use for energy storage.
The cellulose fiber we call wood is made of thousands of glucose molecules
linked into giant chains that no longer taste sweet. (74)
The ancient Greeks, for example, treated pain with a tea made by
boiling willow leaves and bark, a tea modern scientists now know contains
silicon, a precursor of acetylsalicylic acid—aspirin. (75)
More recently, researchers isolated and synthesized the chemical
ginkgolide from the tree for use in treating asthma, toxic shock and other ills.
A. For centuries, the Chinese have derived medicines from the ginkgo tree.
B. Through photosynthesis, an acre of trees produces enough oxygen to
sustain three humans.
C. As scientists unlock the secrets of trees, they uncover surprising
tacts.
D. Trees have always been green machines, producing substances that humans
learned to use.
E. You think, at 150 or more years, giant tortoises can live a long time
F. And the morning newspaper was printed on the processed wood pulp
we call paper.