登录
Ⅲ.Read the article and complete the following tasks.
What Is a Tree?
When it comes to trees, America is truly unique. Did you know that America is home to the tallest, oldest and largest trees in the entire world? America not only has a special day, Arbor Day, when it is a tradition each year to plant new trees, but on December 10, 2004, the oak tree officially became a new national symbol for the United States of America.
A tree is the largest type of plant and can live to be thousands of years old. A tree is made of wood and has a long stem called a trunk. The trunk is covered in an outside layer called bark and has roots that grow into the ground to provide support and nutrients. Above ground, the trunk grows upwards, branches grow outwards and leaves grow from the branches.
Types of Trees
There are two main types of trees, deciduous (shedding) trees and conifers (evergreen). Depending on what climate the deciduous tree lives, warm or cold, it will shed and grow new leaves at different times during the year. Conifers shed their needle - like leaves each year but are never completely without them, which makes them forever green!
How Trees Live and Grow
When the roots and leaves of a tree are fully grown, the tree can then produce its own food and also provide oxygen (air) into the atmosphere through a process called photosynthesis.
Each year trees grow upward and outward. Just under the bark of a tree is the phloem, which food travels through to get to the different parts of the tree. The xylem (sapwood) layer that is under the phloem allows water to be carried from the roots up to the top of the tree. New sapwood is produced each year. The neat thing about the old sapwood is that it makes a ring inside the tree each year. You can count these rings to find out the age of the tree.
1. What do people usually do on Arbor Day in America?
.
2. What kind of trees has been a new national symbol for the USA since 2004?
.
3. What are the main parts of a tree?
.
4. What are the two main types of trees?
.
5. How do trees live and grow?
.
6. What can tree rings tell us?
.
What Is a Tree?
When it comes to trees, America is truly unique. Did you know that America is home to the tallest, oldest and largest trees in the entire world? America not only has a special day, Arbor Day, when it is a tradition each year to plant new trees, but on December 10, 2004, the oak tree officially became a new national symbol for the United States of America.
A tree is the largest type of plant and can live to be thousands of years old. A tree is made of wood and has a long stem called a trunk. The trunk is covered in an outside layer called bark and has roots that grow into the ground to provide support and nutrients. Above ground, the trunk grows upwards, branches grow outwards and leaves grow from the branches.
Types of Trees
There are two main types of trees, deciduous (shedding) trees and conifers (evergreen). Depending on what climate the deciduous tree lives, warm or cold, it will shed and grow new leaves at different times during the year. Conifers shed their needle - like leaves each year but are never completely without them, which makes them forever green!
How Trees Live and Grow
When the roots and leaves of a tree are fully grown, the tree can then produce its own food and also provide oxygen (air) into the atmosphere through a process called photosynthesis.
Each year trees grow upward and outward. Just under the bark of a tree is the phloem, which food travels through to get to the different parts of the tree. The xylem (sapwood) layer that is under the phloem allows water to be carried from the roots up to the top of the tree. New sapwood is produced each year. The neat thing about the old sapwood is that it makes a ring inside the tree each year. You can count these rings to find out the age of the tree.
1. What do people usually do on Arbor Day in America?
.
2. What kind of trees has been a new national symbol for the USA since 2004?
.
3. What are the main parts of a tree?
.
4. What are the two main types of trees?
.
5. How do trees live and grow?
.
6. What can tree rings tell us?
.
答案
1. Plant new trees.
2. The oak tree.
3. Trunk, bark, roots, branches and leaves.
4. Deciduous trees and conifers.
5. When the roots and leaves are fully grown, trees produce their own food and provide oxygen through photosynthesis. They grow upward and outward each year, with phloem transporting food and xylem carrying water.
6. The age of the tree.
2. The oak tree.
3. Trunk, bark, roots, branches and leaves.
4. Deciduous trees and conifers.
5. When the roots and leaves are fully grown, trees produce their own food and provide oxygen through photosynthesis. They grow upward and outward each year, with phloem transporting food and xylem carrying water.
6. The age of the tree.
