5.3Find the answers to the following questions in the text 1:

1. What are the main functions of a trunk?

2. What is the role of an outer bark?

3.How does the stem transport water and minerals up from the roots to the leaves?

4. What is a cambium?

5. What function does a cambium perform?

6. Can you find out how much the stem grows larger in diameter each growing season?

5.4 Complete the sentences with the following verbs: connects, transports, supports, protects, acts.

The trunk of a tree, which is protected by a tough outer covering of bark, …the roots to the branches. The trunk … water and minerals from the soil to the rest of the tree. The trunk … the tree and as it grows taller than the plants around it, it is able to reach more sunlight, which is essential for growth. The outer bark on the trunk … the inside of the tree from injury and from drying out. It also … as an insulator against cold and heat.

5.5 Find the sentences with the ing-forms of the verbs in the text 2 and explain their using.

5.6 Choose the correct answer for the questions:

1. What tissue does form heartwood?

Xylem, cambium, phloem

2. What cells can develop into any type of tissue?

Xylem, cambium, phloem

3 What tissue is located just outside of cambium?

Xylem, cambium, phloem

4 What tissues do contain fiber cells which form a tissue that strengthens the stem?

Xylem, cambium, phloem

5. What tissue is a food conducting one?

Xylem, cambium, phloem

5.7 Choose the correct word.

Trees come in various shapes and sizes but all have the (some, same) basic structure. They have a central column (called, is called) the trunk. The bark-covered trunk supports a framework of branches and twigs. This framework is called the crown. Branches in turn bear an outside covering layer of (leaf, leaves). A tree is anchored in the ground using a network of roots, which spread and grow (thicker, thick) in proportion to the growth of the tree above the ground. In a mature tree, most of the cells of the trunk, roots, and branches are dead or (inactive, active). All (grow, growth) of new tissue takes place at only a few points on the tree, by the division of specialized cells. These (active, actively) growing areas are located at the tips of branches and roots and in a thin layer just inside the bark. (Last, Lastly), trees have reproductive structures; either flowers or cones.

5.8 Skim the texts 3and 4. Title them. Write down an annotation of the texts. Text 3

S

Figure 5.2

ap is the fluid carried inside the xylem or phloem of a plant, circulating to distribute food and water to various parts of the plant. Common uses of the word “sap” include any fluid within a plant body, especially various defensive compounds, such as latex, resins and mucilage. Gummosis is the formation of patches of a gummy substance on the surface of certain plants, particularly trees (figure 5.2).

This occurs when “sap” (technically a latex) oozes from wounds or cankers as a reaction to outside stimuli such as adverse weather conditions, infections,insect attacks (figure 5.3), or other mechanical damage.

I

Figure 5.3

n many species, the sticky nature of sap has the effect of plugging wounds and thus deterring attacks by insects, bacteria and fungi.

Maple tree xylem sap is the basic ingredient in maple surup. The sap of the rubber tree is used to make latex, which is vulcanized to make rubber. Spruce gum is another tree sap that was used by Anishinaabe peoples in Canada quick repairs to wood articles. The sap was collected and used in its raw form. Chewed, it makes a good emergency deep woods survival food.

Pine sap collection for the naval stores industry created the wealth that was a substantial part of the agricultural economy of the southeastern United States between the 1860s and 1960s. In some countries (e.g., Latvia) it is usual to collect the sap of birch trees for human consumption; the sap is extracted during spring and can be used fresh or fermented.

Text 4

The tree gets its food from the air and the soil. The rootlets have the power of absorbing the dissilved mineral salts in the soil in which they remify (branch).Organic matter is concerned in the soil thanks to the breaking up of dead leaves by a fungus. So that the fluid that is taken up by the roots is not merely the water. But water plus disolved mineral matter and nitrigen. At the same time as the roots are thus absorbing liquid nutriment, the leaves, pierceds with thousands of little stomata, take in atmospheric air. Stomata or mouths are small openings in the upper tissues of the leaf through which gases (carbon dioxide, oxygen, water vapor) are exchanged.