Tag: useful and harmful bacteria
Questions Related to useful and harmful bacteria
Nitrogen fixing bacteria converts
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N$ _2$ $\longrightarrow$ NH$ _3$
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NH$ _4^+$ $\longrightarrow$ Nitrates
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NO$ _2$ $\longrightarrow$ NO$ _3$
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NO$ _3$ $\longrightarrow$ N$ _2$
- Conversion of atmospheric inert nitrogen into usable ammonia is termed as nitrogen fixation which is carried out by free-living symbiotic bacteria.
- They have a multisubunit enzyme complex, nitrogenase, which catalyzes the reduction of nitrogen to ammonia. The oxidation of ammonia (NH$ _4$) to nitrite (NO$ _2^-$) and finally to nitrate (NO$ _3^-$) is called as nitrification. It is carried out by nitrifying bacteria.
- Nitrifier bacteria, Nitrobacter and Nitrococcus, convert nitrite into nitrate. Denitrification bacteria carry out the final step in returning nitrogen back to the atmospheric reservoir. They reduce the nitrates into nitrogen.
Free living nitrogen-fixing bacteria are found in
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Air
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Soil
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Root nodules
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None of above
Earth’s atmosphere contains 78% nitrogen but it cannot be used by living organisms due to its inert form. This inert nitrogen is fixed into biologically active ammonia by free living or symbiotic bacteria and other microorganisms. The free living bacteria are present in soil where they perform nitrogen fixation; example: Azotobacter, Azospirillum and Clostridium. This makes option B correct. The finger like projections on roots of legumes, termed as root nodules, carries Rhizobium bacteria which in turn are responsible for nitrogen fixation. Legume get ammonia from Rhizobium and provide carbohydrates as an energy source to them; a symbiotic relation. This makes option C incorrect as root nodules harbour symbiotic bacteria. Nitrogen fixation does not occur in air as none of nitrogen fixing microbes are present in air; option A is incorrect. Thus, the correct answer is option B.
Free-living Nitrogen fixers
(a) Azospirillum (b) Azotobacter (c) Rhizobium
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a, b
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a, c
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b, c
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All of the above
Bacterias like Azotobacter and Azospirillum fix atmospheric Nitrogen while free living in soil, thus enriching Nitrogen content of soil.
Which of the following is free-living aerobic non-photosynthetic nitrogen fixing bacterium?
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Rhizobium
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Azotobacter
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Nostoc
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Azospirillum
Azotobacter is free-living aerobic non-photosynthetic nitrogen fixing bacterium which have wide variety of metabolic abilities, they fix atmospheric nitrogen as they produce nitrogenase enzyme and convert it to ammonia. They are free living in soil and do not associate as symbionts.
The common nitrogen-fixer in paddy fields is
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Frankia
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Rhizobium
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Azospirillum
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Oscillatoria
Mark the incorrect statement
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Bacteria also grow on food particles that may be lodged between our teeth
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Acids produced by these bacteria corrode the tooth enamel and cause cavities
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Many microbes grow in water bodies and increase their oxygen level
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None of these
Many micro - organisms grow water bodies and decrease their oxygen level. This is harmful to the other organisms living in those water bodies.
Thermococcus, Methanococcus and Methanobacterium exemplify
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Bacteria whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria
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Bacteria that contains cytoskeleton and ribosomes
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Archaebacteria, that contain protein homologous to eukaryotic core histones
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Archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled
Thermococcus, Methanococcus, and Methanobacterium are Archaea whose histones are shorter than eukaryotic histones and are assembled in tetramers.
Identify the disease caused by bacteria from the following
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Amoebic dysentery
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Arthritis
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Beri-beri
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Diphtheria
Amoebic dysentery is caused by Entamoeba histolytica, a protozoan parasite. Arthritis is an inflammation of joints. It is caused by attack on immune system, injury or metabolic abnormalities. Beriberi is a disease caused by a vitamin B$ _1$ deficiency. Diphtheria is an infectious disease caused by the bacterium Corynebacterium diphtheriae.
The bacteria which lacks flagella and moves by gliding are
included in
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Spirochaetes
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Rickettsia
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Myxobacteria
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Eubacteria
Cyanobacteria are also called myxobacteria. In which flagella one completely absent but the movement occurs in some genera by special gliding motion. Such movement are connected with the secretion of mucilage.
Identify a bacterial disease from the following.
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Tetanus
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Polio
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Filaria
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Malaria
Tetanus is also called as lockjaw. It is a disease caused by bacterium Clostridium tetani. It affects the nerves that control the muscle movements. Symptoms include difficulty swallowing, difficulty breathing, muscle spasm. Polio is a contagious disease caused by a poliovirus. It attacks the nervous system. It mainly affects the small children. Filaria is a parasitic disease caused by nematode parasites of the order Filariidae. It spreads by mosquitoes and black flies. Malaria is a disease is caused by Plasmodium protozoa. It is transmitted through the bite of the Anopheles mosquito. Symptoms include fever, aches, nausea.