Page 78 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

(e) Denitrifying bacteria convert soil (c) Most of them live in or near water,
nitrates into atmospheric nitrogen; or in moist places.
therefore, they reduce soil fertility. (d) Some protoctists are autotrophs

(manufacture their own food) while
Exercise 5.2
FOR ONLINE READING ONLY
others are heterotrophs (obtain
1. Your friend has disposed a fruit nutrients from other organisms).
to a dump site. Explain what may (e) They include mobile and sessile
happen to a fruit overtime and species.
provide reasons why the process (f) Some protoctists reproduce sexually
is important for environmental
conservation. and others asexually while others
2. Students are advised to wash their reproduce both sexually and
hands after handling samples of asexually.
bacteria. What is the reason for (g) Many protoctists have locomotory
this advice? structures, such as cilia, flagella or
3. Describe a generalised structure pseudopodia.
of a bacterium.

Phyla of kingdom Protoctista
Kingdom Protoctista Protoctista is subdivided into several
Members of this kingdom phyla. Only five phyla of this kingdom
include Amoeba sp., Euglena sp., will be described in this section. These

Plasmodium sp., Paramecium sp., and phyla are Rhizopoda, Apicomplexa,
Trypanosoma sp. Euglenophyta, Ciliophora, and

Zoomastigina.
Task 5.4
Phylum Rhizopoda
From the library and reliable internet Organisms included in phylum Rhizopoda
sources, search information about move and feed using structures known as
protoctists (characteristics, advantages, pseudopodia (singular is pseudopodium).
and disadvantages). An example of organisms found in this
phylum is Amoeba sp. Parasitic amoeba
Characteristics of protoctists includes Entamoeba histolytica, which
(a) They are eukaryotic as they have feeds on cells of the human colon and
nucleus and other membrane cause amoebic dysentery. Free living

bound organelles. amoeba are found in sea water,
(b) Most of them are unicellular freshwater, and in the soil. They can
organisms. also be found in muddy ponds and slow

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