ВУЗ:
Составители:
Рубрика:
Text 5
I. Read the text and say what it is about.
AMOEBA
Amoebae are tiny pond-living animals visible to the naked eye. They are
vary difficult to find among mud and other debris at the bottom of ponds. Before
we can understand the methods of reproduction in amoeba we must learn about
its structure.
The body of amoeba is bounded by a protoplasmic membrane and the thin
layer of protoplasm immediately inside it is devoid of granules and is called
plasmagel. The main part of the body is made of a more fluid type of protoplasm
called plasmagel and it contains granules of stored food. If you examine an
amoeba in a drip of water under a microscope you will see the plasmasol
flowing, often in more than one direction, producing a change in shape of the
animal as pseudopodia.
It. is usually easy to distinguish the posterior end of the body by the
numerous very short pseudopodia there, and in the plasmasol at this end is a
spherical vacuole which gradually fills with water and then contracts so
expelling its contents to the exterior before filling once more. This contractile
vacuole keeps the water content of the body at a steady level by counteracting
the entry of water from outside. Also in the plasmasol are a transparent nucleus
and several food vacuoles which contain the food undergoing digestion after it
has been engulfed by pseudopodia and so taken into the body.
II. Remember the following words, consult a dictionary about the way they
are pronounced:
amoeba (pl. amoebae) амеба
tiny крошечный
pond-living живущие в прудах
mud грязь
bottom дно
plasmagel плазмагель
plasmasol плазмазоль
shape форма
pseudopodiapl.(sing. seudopodium) ложноножки
posterior end задний конец
contract сжимать(ся), сокращать(ся)
contents содержимое
10
Страницы
- « первая
- ‹ предыдущая
- …
- 9
- 10
- 11
- 12
- 13
- …
- следующая ›
- последняя »
