The cell. Кулагина Ж.Д. - 15 стр.

                                          15
1. The work was neither difficult nor easy. 2. His answers were both simple
and honest. 3. I like both of these plants. 4. Neither of the words "science" and
"life" can be simply defined. 5. Most organisms may readily be identified as
either plants or animals. 6. I like both the flowers and the leaves of this plant. 7.
We shall either work here or go to the library. 8. Either of the vegetable crops
mentioned is very rich in vitamins. 9. Both functions of this organ are important.
10. Both water and air are necessary for living organisms. 11. This fruit may be
used for food either in fresh or in frozen state. 12. We shall work neither today
nor tomorrow. 13. I shall not come tomorrow either. 14. General properties of
protoplasm are the same both in plants and animals. 15. All acids whose
strength is even a little either greater or less than carbonic acid lack this
property.

                                       Step 2
      Ex. 9. Read and translate text А.

                                     TEXT A
            THE CELL MEMBRANE AMD THE СЕLL WALL.
       Animal cells are bounded by a thin, delicate, semi-permeable membrane
that can only be seen under the electron microscope. The membrane consists of
two or three layers, 60 to 70 Ängströms thick, and is permeated by openings.
Through these openings the cytoplasm of the cell communicates with that of
neighbouring cells and with the channels of the endoplasmic reticulum. The
protoplasmic body of plant cells is always encased in addition to the thin cell
membrane by a cell wall consisting of a polysaccharide and cellulose, which is
seen distinctly under a microscope even at low magnification. The presence of
this cellulose wall is the main and principal feature distinguishing the cells of
plants from those of animals.
       The cell membrane and the cell wall play an important part in protecting
the cell against injury and harmful influences of the environment as well as in
controlling the composition of the cell contents. All the nutritive substances that
enter the cell have to pass through the membrane; all the metabolic waste and
excretory products of the cell move across it in the opposite direction when
ejected. The cell wall is perforated by many small openings through which the
cytoplasms of neighbouring cells communicate, but the protoplasm of one cell
never enters another cell. The cell is the true anatomical unit of living matter.

      Ex. 10. Put questions to the missing parts of the sentences in writing.

       1. Animal cells are bounded by... 2. It consists of ... layers. 3. The cell
membrane has... 4. These openings are for... 5. The protoplasmic body of plant
cells is encased by ....6. The cell wall is composed of ... 7. ... distinguishes the
cells of plants from those of animals. 8. The cell wall and cell membrane protect