Page 115 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six
P. 115
Biology for Secondary Schools
Activity 5.16: Observing the external nervous system made up of the
features of fish, chicken, frog, lizard well-developed brain and a spinal
and rat or mouse cord.
Materials: Preserved or fresh Distinctive features of chordates
FOR ONLINE READING ONLY
specimens of fish, frog, chicken, catfish, Chordates have unique features that
lizard, rat, charts showing pictures or differentiate them from other animals.
drawing of fish, frog, chicken, lizard, Chordates have the following features
rat, hand lens, scalpels, notebook, pen at some stages of embryological
and a tray development.
(a) A supporting skeletal structure
Procedure called notochord. In many
1. Place each specimen on a tray. vertebrates, the notochord is
2. Observe each specimen carefully. replaced by the vertebral column
3. Describe the external features during development.
you observed, including the (b) A dorsal hollow tubular nervous
arrangement of scales, presence of tissue known as nerve cord that is
gills, type of fins, and the overall found inside vertebral column.
shape of each specimen.
(c) Gill slits at least during early
developmental stages and may later
Question develop into various structures, such
What features distinguish a fish from
a frog? as gills in fish or component of the
ear and throat in mammals.
General characteristics of chordates (d) Post anal tail. In humans it is only
(a) They occupy both terrestrial and present during embryonic stages.
aquatic habitats.
(b) Most chordates have a complete Advantages of chordates
digestive system with two (a) Chordates, such as fish, chicken,
openings, the mouth and anus. goats, sheep, cattle and buffalo are
(c) Most chordates have a ventral used as source of food to human
heart. beings and other animals.
(d) Most chordates have a closed (b) Their excreta in the form of faeces
circulatory system. or dung are used as organic manure
(e) Most have endoskeletons made up which adds nutrients to the soil,
of bones and cartilages. thus improving soil fertility.
(f) Some chordates have central (c) Products from mammals have
Student’s Book Form One Student’s Book Form One 109
15/10/2024 09:24:35
Biology FORM 1 new.indd 109
Biology FORM 1 new.indd 109 15/10/2024 09:24:35
