Microbiology and Nitrogen Cycle

Green Fluorescent Protein (GFP) was first isolated from the jellyfish Aequorea victoria, found in the Pacific Northwest. This protein revolutionized molecular biology by enabling visualization of cellular processes. The other options are misspelled or incorrect organism names.

E. Coli (Escherichia coli) is a common bacteria found in the intestines of humans and animals, but certain strains can contaminate food like beef and vegetables. These pathogenic strains cause foodborne illness and are a major concern in food safety.

Spontaneous generation (abiogenesis) - the idea that life can arise from non-living matter - is not an attribute of bacteria. Modern biology confirms that bacteria arise only from pre-existing bacteria (biogenesis), not from non-living matter. Growth, reproduction, and respiration are all fundamental bacterial characteristics.

One gram of healthy soil contains approximately 10 million bacteria. Soil is incredibly rich in microbial life, which plays crucial roles in decomposition, nutrient cycling, and plant growth. The correct answer is 10 million (D).

Azotification is also known as 'associative nitrogen fixation' (or composite fixation), where free-living bacteria like Azospirillum fix nitrogen in close association with plant roots without forming nodules. Option A correctly states 'composite fixation'. Option C is incorrect because Rhizobium causes symbiotic fixation in nodules, not free/associative fixation. Option D refers to atmospheric deposition, not biological fixation.

Leguminous plants host nitrogen-fixing bacteria (like Rhizobium, not Nitrosomonas which are nitrifying bacteria) in root nodules that convert atmospheric N2 into ammonia. When legumes are multiple-cropped, they naturally replenish soil nitrogen, significantly reducing the need for synthetic nitrogen fertilizers. Note: the question incorrectly names Nitrosomonas, but the concept remains correct.

Beans and other legumes (like pulses) have a symbiotic relationship with Rhizobia bacteria that live in nodules on their roots. These bacteria convert atmospheric nitrogen into ammonia, which plants can use. This process is called nitrogen fixation. Rice, wheat, and maize are cereals that do not have this nitrogen-fixing ability.

Rhizobium japonicum is the specific nitrogen-fixing bacteria that forms symbiotic nodules on soybean roots. Different Rhizobium species are host-specific: R. leguminosarum infects peas, R. phaseoli infects beans, and R. trifolii infects clover.

Bacteria is the plural of bacterium, and since the subject is doing something (growing), the plural form is correct. 'Bacterium' is singular, 'Bacterias' is incorrect (bacteria is already plural), and possessive 'Bacteria's' would mean something belonging to bacteria, not the bacteria themselves.

Bacteria is the plural form of bacterium. The sentence uses the plural verb were (implied), so the subject must be plural. Bacterium would be singular, while bacteria is the correct plural form.

It is a Gram-positive, rod-shaped bacteria. It can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase.

Azotobacter vinelandii is a free-living N₂ fixer which is capable of producing numerous phytohormones and vitamins in the soil. It is diazotroph. It is used to study nitrogen fixation.

It is a rod-shaped, Gram-positive, endospore forming bacteria. It is generally employed as a soil inoculant in horticulture & agriculture.

It is a Gram-negative bacillus bacterium species, and an obligate anaerobe of the gut.