Page 108 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

(a) They cause diseases, such as hence drains photosynthetic
elephantiasis or bancroftian products.
filariasis which affects the human
lymphatic system. This results in Phylum Annelida
accumulation of the lymph in legs, The word Annelid is derived from a
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hands, mammary glands or scrotal latin word “annelus” which means little
sacs. ring. Thus, members of this phylum are
(b) They cause ascariasis in humans known as ringed or segmented worms.
and pigs. This may lead to Annelida is a large phylum comprising
obstruction of the gut and may ragworms, peacock worms, leeches,
also cause anaemia. and earthworms. Examples of annelids
(c) Some species of roundworms are shown in Figure 5.30.
cause root knot galls in plants,

(a) (b) (c) (d)

Figure 5.30: Examples of annelids (a) marine ragworm (b) peacock worm (c) blood-
sucking leech (d) earthworm

General characteristics of annelids first segment above the mouth called
(a) They have elongated, cylindrical prostomium.
bodies that are divided into distinct (g) They are commonly found in soil,

segments. freshwater, and marine environment
(b) They have bilateral symmetrical while some species are parasitic.
bodies.
(c) They reproduce both asexually and Distinctive features of annelids
sexually. (a) Most annelids have hair-like
(d) They have a moist outer covering structures called chaetae made
called cuticle. up of chitin. These are used for
(e) They have closed circulatory system locomotion.
whereby the blood flows within the (b) They have a segmented body.
blood vessels.
(f) They have a lip-like extension on the

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