Page 83 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

Characteristics of Paramecium sp.
(a) They are unicellular and slipper- Advantages of Paramecium sp.
shaped. Paramecium sp. play important
(b) They are eukaryotes. ecological role in the environment as
(c) They are heterotrophic. they help to clean up small particles of
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(d) They live in freshwater. debris in the water as well as feeding
(e) The body is covered with short on small animals.
hairy structures called cilia.
(f) They use cilia to move and to Disadvantages of Paramecium sp.
create a feeding current. (a) Some species of Paramecium
(g) The body of the paramecium cell invade and destroy the lining of
is enclosed by a stiff but elastic the intestine, causing a disease
membrane, called the pellicle.
(h) Food enters the organism through called balantidiasis.
an opening called the oral groove. (b) Paramecium sp. feed on bacteria
(i) They have food vacuoles which which decompose sewage. This
are formed to hold and digest food may delay the decomposition of
particles. sewage.
(j) They have anal pores which are
used for elimination of undigested Phylum Zoomastigina
food. Organisms found in this phylum
(k) Paramecium sp. can reproduce either are unicellular flagellate protoctists.
asexually or sexually, depending
on their environmental conditions. Generally, they are found in the intestine,
Asexual reproduction takes place but can also be found in blood stream
when enough nutrients are available, or in the heart. Trypanosoma sp. is
while sexual reproduction takes an example of members of phylum
place under conditions of starvation. Zoomastigina. Figure 5.12 shows the
(l) Contractile vacuoles regulate the structure of a Trypanosoma sp.
amount of water in the cytoplasm.

Kinetoplast
Flagellum
Pellicle
Food granules

Undulating membrane
Nucleus

Figure 5.12: Structure of a Trypanosoma sp.

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