Give a short summary of the text.

“Aqua words”

Water is central to all life and life activities. Plants and animals must have water to survive. Water represents about 75 % of a person’s body weight and covers nearly 75% of the earth’s surface. Nearly everything on earth can be directly or indirectly traced to a connection with water. Rocks channel water into streams and rivers carry water across the land. Ponds, lakes, marshes, and swamps often hold water in place. Trees draw water from the soil and transport it up into leaves and out again into the air. Clouds are airborne carriers of water across the sky.

Wildlife water for survival. The water must be clean and free of toxic contamination. Humans use water for many purposes other than drinking. Care must be taken to protect water quality.

Water is a source of beauty and recreation. It is the basis of a massive planetary transportation system. Water grows our food, cools, our cars, and is one of the first things on the list of substances the astronauts take into space. The driest desert take into space. The driest desert has water- and there are 320,000,000 cubic miles of water in the oceans. The tiny plants that live in the earth’s oceans – phytoplankton – produce one-third or more of our oxygen, a gas vital to vertebrate respiration.

TEXT 12 “How A Plant Lives”

I. Read and translate the text:

Trees are woody plants, growing with a single stem. They are the largest members of the plant world, ranging in height from 20 to 300 feet or more, according to species and conditions of growth. Trees may be said to consist of three parts:

- the roots which hold the tree in place and take up from the soil water and certain mineral substances needed for the trees growth;

- the trunk or stem which supports the crown and supplies it with water and food from the roots; and

- the crown. In this part the most important processes are taking place.

The materials upon which a tree feeds are derived from the soil and the air. The roots of a tree absorb water from the soil and with it the necessary nutrition and elements of the soil. The amount of water taken up by the roots is usually much larger than is required in the chemical processes which go on in the leaves. The tree gives away this unused water by a process known as transpiration. Great quantities of water vapor tend to keep the air in the forests humid and favorable to growth.

In the lives the food necessary for the trees’ growth is manufactured. The raw food materials which reach the tree through the roots and the leaves are digested in the leaves. They are then sent to all living parts of the roots, stem and crown where they are either used at once or stored away for later use.

Like all other plants and like animals trees breathe. The breathing is done through the leaves and the bark. Respiration is the factor supplying the energy with the aid of the green matter in the leaves. The energy is supplied by sunlight; the plant takes up carbon dioxide gas of which there is always a small amount in the atmosphere. The carbon is used to elaborate the organic compounds. The carbon assimilation is a most important biochemical process. The air would deteriorate rapidly if plants did not take up carbon dioxide and give off oxygen.

The earlier structure of wood is known as heartwood the outer, later sections as sapwood. The difference is in the moisture content and aging. Heartwood is found in all species of coniferous trees such as pine, fir, spruce, larch and in certain deciduous trees, for example, in oak, ash, elm, poplar, as well as in tropical trees.

Dead or heartwood trees no longer perform a function in the living tree. Hence, if the tree is injured by fire, the heartwood trees are in greater danger; the sapwood trees have greater resistance to fungus attack owing to their nature and content. On the other hand, when a tree has been cut and the timber seasoned the heartwood trees are more resistant to fungi and insect pests. The pores through which a leaf breathes are surrounded with tiny cells which serve to open and close the pores as the weather changes and as moisture and life vary. Trees grow from the top and in diameter; the side growth is also called secondary growth. Wood has layers of growth which appear as circles around the center. They are actually elongated cells and cluster of tubes. This makes it possible to split the wood vertically and prevent splitting across the grain. Wood varies in weight and in specific gravity. Some wood is heavier than water as, for example, the black iron in Florida, which will sink in water. With a few exceptions dry wood is lighter than water, but the moisture content of wood greatly affects its weight.

II.. Work in pairs. Ask questions according to the model:

What do you call the part of a plant coming up from the root? --- We call it a stem.

1. the part of a plant or a tree which is normally in the soil; 2. The part of a tree covered with leaves; 3. The outer covering of the stem and branches; 4. The layer between the outer bark and the wood; 5. The darker part in the center of a tree; 6. a tree which is green in all seasons; 7. a tree that loses leaves every year; 8. Loss of water vapor from the surface of leaves

III. Find in the text words and word combinations close to the following:

Trunk, breathing, with the help of, therefore, due to, specific weight, a dead tree, small cells, growth in diameter, influence, to occur, quantity, broadleaf trees

IV. Using the text A tell about the functions of each part of the tree.

V. Ask questions. The following sentences will be answers:

1. Trees consist of three main parts. 2. Some trees reach the height of 300 feet.3.The trees breathe through the leaves and the bark. 4. One may know the age of a tree by its annual rings.