May 25, 2013

Senior Inter Botany Long Answer Type Questions

Long answer type questions (8 marks)

“Bacteria are friends and foes of man”. Discuss.

Bacteria are called “friends and foes of man” as they are both beneficial
and sometimes causing harm to human beings.
Many bacteria cause diseases to human beings like Tetanus – Clostridium
tetani, Cholera – Vibrio cholera, Typhoid – Salmonella typhi, Diphtheria –
Corynebacterium diphtheria, Tuberculosis – Mycobacterium tuberculosis
Pneumonia – Diplococcus pneumoniae, Leprosy – Mycobacterium leprae
Gonorrhoea – Neisseria gonorrhea and Syphilis – Treponema pallidum.
Clostridium botulinum caused spoilage of food called Botulism. Some of
the bacteria cause plant diseases like Blight of rice – Xanthomonas oryzae,
Citrus canker – Xanthomonas axonopodis pv. citri and Crown gall of apple
and pear – Agrobacterium tumefaciens.

At the same time a large number of bacteria are useful to man in many
ways. Saprophytic bacteria cause decomposition of organic wastes and help
in the process of humification and mineralization which are important to
the nutrient cycles. Many bacteria are used for production of antibiotics,
alcohols, enzymes and hormones on industrial scale. Bacterial plasmids are
used as tools in genetic engineering and bio technology. LAB is used for
conversion of milk into curds. Bacteria are also used in sewage treatment.

Some bacteria like Methano coccus and Methano bacillus are useful in
production of bio gas. Bacteria are also used as bio control agents in pest
and diseases control in agriculture. Bacteria like Rhizobium, Azospirillum,
Azotobater are used as bio fertilizers.

Thus it is rightly said that Bacteria are both friends and foes of man.

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