Microbiology of Soils

Q1: A heterocyst is

A a type of spore

B a terminally differentiated cell that fixes nitrogen

C the progenitor of cyanobacterial vegetative cells

D a cell that carries out oxygenic photosynthesis

ANS:B - a terminally differentiated cell that fixes nitrogen

No answer description is available.

Q2: The diagnostic enzyme for denitrification is

A nitrate reductase

B nitrate oxidase

C nitro oxidoreductase

D none of these

ANS:A - nitrate reductase

No answer description is available.

Q3: Nitrogen fixation

A changes the free nitrogen (N2) to a form usable by plants

B especially changes nitrogen compounds, mostly amines such as NH2

C both (a) and (b)

D fix the free nitrogen (N2) by which it should not be usable by plants

ANS:C - both (a) and (b)

No answer description is available.

Q4: The phenomenon of commensalism refers to a relationship between organisms in which

A one species of a pair benefits

B both the species of a pair benefit

C one species of a pair is more benefited

D none of the above

ANS:A - one species of a pair benefits

No answer description is available.

Q5: Denitrification may be distinguished as

A dissimilative

B assimilative

C both (a) and (b)

D blue baby syndrome

ANS:C - both (a) and (b)

When an inorganic compounds (nitrate, sulfate, carbon dioxide) is reduced for use as a nutrient source, its is said to be assimilated and the reduction process is called assimilative metabolism.

The use of Nitrate, sulfate or CO2 as electron acceptors for energy metabolism in an anaerobic respiration is called dissimilative metabolism.

Q6: Which of the following is capable of oxidizing sulfur to sulfates?

A Thiobacillus thiooxidans

B Desulfotomaculum

C Rhodospirillum

D Rhodomicrobium

ANS:A - Thiobacillus thiooxidans

No answer description is available.

Q7: The crops which are involved in nitrogen fixation are

A alfalfa and clover

B soybean

C bean and lupine

D all of these

ANS:D - all of these

No answer description is available.

Q8: The physical structure of soil is improved by the accumulation of

A mold mycelium

B minerals

C water

D all of these

ANS:A - mold mycelium

No answer description is available.

Q9: Nitrogen fixation refers to the direct conversion of atmospheric nitrogen gas into

A ammonia

B glucose

C ATP

D nitrate

ANS:A - ammonia

Why not nitrate?

Q10: Most soil protozoa are flagellates or amoebas, having their dominant mode of nitrogen as

A ingestion of bacteria

B ingestion of mold

C ingestion of fungi

D all of these

ANS:A - ingestion of bacteria

Give Describtion.

Q11: The diagnostic enzyme for nitrogen-fixing organisms is

A nitrogenase

B nitrate reductase

C nitrate oxidase

D none of these

ANS:A - nitrogenase

No answer description is available.

Q12: Which of the following microorganism use H2S as the electron donor to reduce carbon dioxide?

A Chromaticum

B Chlorobium

C Both (a) and (b)

D Rhodomicrobium

ANS:C - Both (a) and (b)

No answer description is available.

Q13: Nitrogen oxidation (nitrification)refers to the

A conversion of ammonium ions into nitrates through the activities of certain bacteria.

B changing of atmospheric nitrogen (N2) to nitrogen compounds

C sulfur is oxidized to the sulfate form through Thiobacillus bacteria

D none of the above

ANS:A - conversion of ammonium ions into nitrates through the activities of certain bacteria.

No answer description is available.

Q14: An example of a symbiotic nitrogen fixer is

A Azotobacter

B Beijerinckia

C Clostridium

D Rhizobium

ANS:D - Rhizobium

No answer description is available.

Q15: Which of the following statement is not true about composition of biogas?

A It is composed almost exclusively of methane and carbon dioxide

B It also contains with traces of H2S, N2, H2and CO

C It also contains with traces of O2 and Cl2

D Both (a) and (b)

ANS:C - It also contains with traces of O2 and Cl2

No answer description is available.

Q16: Which are the main source of biofertilisers?

A Cyanobacteria

B Bacillus

C Streptococcus

D None of these

ANS:A - Cyanobacteria

No answer description is available.

Q17: Denitrification is carried out

A usually by facultative anaerobes

B predominantly by Pseudomonas spp

C predominantly by Bacillus spp

D all of the above

ANS:D - all of the above

No answer description is available.

Q18: Nitrogen fixation by the microorganisms can be detected by adopting the approach of

A demonstrating growth in a nitrogen free medium

B cultivating the microorganisms in the presence of nitrogen labeled with isotropic nitrogen

C measuring15N2 by mass spectrometer

D all of the above

ANS:D - all of the above

No answer description is available.

Q19: Some microorganisms have the ability to increase the nitrogen content of soils, are called as

A nitrogen fixation

B denitrification

C nitrification

D all of these

ANS:A - nitrogen fixation

No answer description is available.

Q20: Nitrifying bacteria can not be isolated directly by the usual techniques employed to isolate hetrotrophic bacteria. The reasons may be due to

A slow growth

B medium growth

C fast growth

D none of these

ANS:A - slow growth

No answer description is available.

Q21: The nonsymbiotic bacteria which fix nitrogen live in the soil independently are

A Azotobacter

B Clostridium

C considerably less important in comparison to the symbiotic bacteria

D all of the above

ANS:D - all of the above

What is Azatobactor? Please explain in detail.

Q22: The breakdown of cattle manure in biogas is accomplished by which of the following type of bacteria?

A Hydrolytic

B Transitional

C methanogenic

D All of these

ANS:D - All of these

No answer description is available.

Q23: Which of the following fungi on infecting crop roots can improve their uptake of phosphorus and other nutrients?

A Saccharomyces cerevisiae

B VA Mycorrhiza

C Candida torulopsis

D Aspergillus niger

ANS:B - VA Mycorrhiza

No answer description is available.

Q24: Assimilative denitrification is done by

A plants

B fungi

C prokaryotes

D all of these

ANS:D - all of these

No answer description is available.

Q25: Syntrophism involves

A exchange of nutrients between two species

B exchange of nutrients among species

C no exchange of nutrients between two species

D no exchange of nutrients among species

ANS:A - exchange of nutrients between two species

No answer description is available.

Q26: The transformation of nitrates to gaseous nitrogen is accomplished by microorganisms in a series of biochemical reactions. The process is known as

A nitrification

B denitrification

C nitrogen fixation

D ammonification

ANS:B - denitrification

What is the difference between compound fertilizers and blends or mixed fertilizers? Please explain me.

Q27: Denitrification is

A reduction of nitrate (NO3-) to nitrogen gas

B reduction of nitrate to organic nitrogen compounds

C both (a) and (b)

D changing of atmospheric nitrogen (N2) to nitrogen compounds

ANS:C - both (a) and (b)

Reduction of nitrate to organic compounds (proteins, amino acids) is called assimilation. Then why it is putting into denitrification category.

Q28: The microbial ecosystem of soil includes

A biotic components of soil

B abiotic components of soil

C biotic and abiotic components of soil

D none of the above

ANS:C - biotic and abiotic components of soil

No answer description is available.

Q29: The energy value of biogas is typically

A 400-700 BTU/ft3

B 1,000 BTU/ft3

C 1500 BTU/ft3

D more than 5000 BTU/ft3

ANS:A - 400-700 BTU/ft3

No answer description is available.

Q30: __________ play a key role in the transformation of rock to soil.

A Cyanobacteia

B Pectin decomposing bacteria

C Nitrifying bacteria

D De-nitrifying bacteria

ANS:A - Cyanobacteia

No answer description is available.

Q31: The nitrogenase consists of

A dinitrogenase

B dinitrogenase reductase

C both (a) and (b)

D none of these

ANS:C - both (a) and (b)

No answer description is available.

Q32: For rapid decomposition by microbes, the substrate should have a C/N ratio of

A 10-20

B 20-30

C 30-40

D 60-80

ANS:C - 30-40

No answer description is available.

Q33: Which of the following is not the biofertilisers producing bacteria?

A Nostoc

B Anabaena

C Both (a) and (b)

D Clostridium

ANS:D - Clostridium

Clostridium is a bacteria.

Q34: Which of the following soil microorganism is involved in the reduction of sulfates to H2S?

A Thiobacillus thiooxidans

B Desulfotomaculum

C Rhodospirillum

D Rhodomicrobium

ANS:B - Desulfotomaculum

No answer description is available.

Q35: The groups of symbiotic bacteria, which have the ability to fix nitrogen

A derive their food and minerals from the legume, and in turn they supply the legume with some or all of its nitrogen

B grow together for a mutual benefit is called symbiosis and so these bacteria are called symbiotic nitrogen-fixing bacteria

C these bacteria are from the genus, Rhizobium

D all of the above

ANS:D - all of the above

No answer description is available.

Q36: The population of algae in soil is __________ that of either bacteria or fungi.

A generally smaller than

B generally greater than

C equal to

D none of these

ANS:A - generally smaller than

No answer description is available.

Q37: In the process of nitrogen fixation, which of the following microorganism is involved?

A Non symbiotic microorganisms only

B Symbiotic microorganisms only

C Non symbiotic and symbiotic microorganisms only

D None of the above

ANS:C - Non symbiotic and symbiotic microorganisms only

No answer description is available.

Q38: The groups of bacteria which have the ability to fix nitrogen from air to soil are

A symbiotic

B nonsymbiotic

C both (a) and (b)

D none of these

ANS:C - both (a) and (b)

No answer description is available.

Q39: Bacteria, as a group, are responsible for

A nitrogen oxidation

B sulfur oxidation

C nitrogen fixation

D all of these

ANS:D - all of these

No answer description is available.

Q40: The conversion of molecular nitrogen into ammonia is known as

A nitrification

B denitrification

C nitrogen fixation

D ammonification

ANS:C - nitrogen fixation

No answer description is available.

Q41: Which of the following is correct?

A Mycorrhizae are fungi that form a mutually beneficial (symbiotic) relationship with plant roots

B The fungi aid in transmitting nutrients and water to the plant roots

C The increased nutrient availability from mycorrhizae is thought to be due to the additional absorbing surface provided by the fungi

D All of the above

ANS:D - All of the above

No answer description is available.

Q42: The organisms responsible for the characteristic musty or earth odor of a freshly plowed field is/are

A Nocardia

B Streptomyces

C Micromonospora

D all of these

ANS:D - all of these

No answer description is available.

Q43: Degree of compost maturity can be assesed by

A infrared technique

B germination test

C both (a) and (b)

D none of the above

ANS:C - both (a) and (b)

No answer description is available.

Q44: Which of the following species of different genera of bacteria are not capable of transforming nitrate to nitrogen?

A Achromobacter

B Agrobacterium

C Alcaligenes

D None of these

ANS:D - None of these

No answer description is available.



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