Page 116 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

commercial value as they are used (g) Their excreta are used for production
in making different products used of biogas which is used as a source
by human beings. For example, of energy.
cattle, sheep and goats provide skin (h) Chordate derived products such as
which is used for making leather in fish oil and shark collagen are used
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tannery industries. Leather is used to to treat diseases in human beings and
make belts, bags, shoes and clothes. livestock. Snake skin, tortoise shell
Many mammals provide horns and and shark fins are used in traditional
hooves which are used for making medicine.
buttons and ornaments. The bones
of mammals are ingredients used in Disadvantages of chordates
making chicken feed. Sheep provide (a) Some chordates are dangerous
wool that is used for production of because they can attack humans,
various products, including clothes. causing injury or death. Examples
(d) Some chordates, such as rats (rodents) of such chordates include
are used in scientific research. They crocodiles, sharks, lions, leopards,
are trained to detect narcotics at the buffalo, elephants and hyenas.
airports and landmines. They are (b) Some chordates are vectors of
also used to detect explosives buried diseases. For example, birds can
underground during the war. They transmit viruses that cause bird
are also used to diagnose diseases flu. Cats and rats can spread fleas
such as, tuberculosis. Police dogs which transmit bacteria and other
are used to track down criminals. pathogens that cause diseases,
(e) Some domestic mammals, such such as plague. Infected dogs can
as cattle and donkeys are trained also transmit rabies, which is a
to perform different duties, viral disease of dogs and can also
such as cultivation of crops and infect humans.
transportation of goods. (c) Some chordates are crop pests,
(f) Some chordates are source of destroying crops in storage or
income. Live animals and animal in the field. Examples of such
product such as meat and milk are chordates include birds, rats,
sold in domestic and foreign markets; monkeys, and pigs.
hence, they are an important source (d) Some snakes, frogs, toads and
of local and foreign currency. Some newts produce toxins which cause
animals are kept in zoos, national skin irritation and even death to
parks and game reserves to attract human beings.
tourists.

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