19. Choose the correct answer:

1. What type are most trees?

A cloned B low C young D wild

2. What do cloned trees have in common?

A identical leaves B identical genes C identical flowers D identical crowns

3. How can trees be divided according to the structure of the vascular system?

A ring-porous or diffuse-porous B deciduous or coniferous C annuals or perennials D creepers and climbers

4. .When are the vessels of a ring-porous tree produced?

A late in the season B in two seasons C in the middle of the season D early in the season

20. Match the parts of the sentences:

1. Some trees are wild, … 2. It's easy to think that all trees of a species … 3. Most trees are … 4. Other trees have been cloned … 5. This distinction is important when … 6. Trees can be divided into … 7. The vascular system of diffuse-porous trees is characterized by … 8. The vessels of a ring-porous tree are generally larger and concentrated … 9. This is significant because it affects …

a) … wild-type trees. b) … treating diseases. c) … vessels spread evenly throughout the sapwood. d) … others are cloned. e) … a tree's susceptibility to vascular wilt diseases. f) … in the outermost layer of sapwood. g) … to produce many trees with identical genes. h) … are alike. i) … ring-porous or diffuse-porous types.

21. Retell the text in Russian.

22. Read and translate Text c in writing using a dictionary: Text c Trees

In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting leaves or branches. In some usages, the definition of a tree may be narrower, including only woody plants, only plants that are usable as timber or only plants above a specified height. At its broadest, trees include the taller palms, the tree ferns, bananas and bamboo.

A tree typically has many secondary branches supported by the trunk. This trunk typically contains woody tissue for strength, and vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark which serves as a protective barrier. Below the ground, the roots branch and spread out widely; they serve to anchor the tree and extract moisture and nutrients from the soil. Above ground, the branches divide into smaller branches and shoots. The shoots typically bear leaves, which capture light energy and convert it into chemical energy by photosynthesis, providing the food needed by the tree for its growth and development.

Flowers and fruit may also be present, but some trees such as conifers instead have pollen cones and seed cones, and others such as tree ferns produce spores.

Trees tend to be long-lived, some reaching several thousand years old. The tallest known specimen on Earth is 115.6 m and they have a theoretical maximum height of 130 m. Trees have been in existence on the Earth for 370 million years. Trees are not a taxonomic group but are a number of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants and make full use of the sunlight.

Trees play a significant role in reducing erosion and moderating the climate. They remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of animals and plants. Tropical rainforests are one of the most bio-diverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, and fruit for food as well as having many other uses.