Page 77 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

Non-pathogenic bacteria (e) Some bacteria produce lactic
These are bacteria that are harmless acid as a result of fermentation of
even when they are in a plants or carbohydrates. This is important in
animal’s body. For example, Rhizobium the production of cheese, yoghurt,
sp. that are found in the root nodules vinegar, and alcohol.
FOR ONLINE READING ONLY
of leguminous plants, help to convert (f) Some bacteria are used to produce
atmospheric nitrogen into nitrates in antibiotics, which are used to treat
the soil. Bacteria in the human gut bacterial infections.
synthesize vitamins K and B12.
(g) Bacteria are used in genetic
engineering to produce hormones,
Advantages of bacteria
(a) Some non-pathogenic bacteria feed such as insulin and human growth
on substances that are harmful to hormone.
the environment, and in the process (h) Bacteria such as Escherichia coli in
neutralize them. For example, they the human gut synthesize vitamins
neutralize petroleum waste from K and B12.
petroleum industries, dyes and
pesticides, thereby making the Disadvantages of bacteria
environment clean. (a) Many bacteria cause infections

(b) Bacteria in the stomach of ruminant and diseases in animals. Some of
animals, such as goats and cattle the common bacterial diseases of
secrete cellulase enzyme. Cellulase animals are typhoid fever caused
enzyme helps in the digestion of by Salmonella typhi, Tuberculosis
cellulose which forms a large part (TB) caused by Mycobacterium
of the diet of ruminants. tuberculosis and gonorrhoea caused
by Neisseria gonorrhoeae.
(c) Nitrogen-fixing bacteria live in the
root nodules of leguminous plants. (b) Some bacteria cause crops diseases.
They convert free nitrogen in the Examples of these diseases are fire
air into nitrates in soil which can blight on pea and apple, and leaf
be used by plants to make proteins. spot in cotton.
(c) Some bacteria cause food spoilage by
(d) Many bacteria are decomposers.
They break down the dead bodies decaying stored food and making it
of plants and animals to release unsuitable for human consumption.
important elements, such as nitrogen, (d) Sulphur bacteria produce sulphuric
carbon, and phosphorus which can acid, which causes damage to buried
be recycled. metal pipes.

Student’s Book Form One Student’s Book Form One 71

15/10/2024 09:24:29
Biology FORM 1 new.indd 71 15/10/2024 09:24:29
Biology FORM 1 new.indd 71