Question

Oxygen is harmful for
(a) Nitrogen-fixing bacteria
(b) Ferns
(c) Chara
(d) Mango tree

Answer 1

Oxygen disables the nitrogen fixation enzymes such as nitrogen reductase, thereby impeding the nitrogen fixation method. In anaerobic environments, some of the nitrogen fixers work to minimize the oxygen level or to allow the oxygen to mix with leghemoglobin.

Complete Answer:
Topic bacteria fixing nitrogen (inorganic compounds used by plants) are microorganisms that are likely to turn airborne nitrogen into fixed nitrogen. These species, which thus play an important part in the nitrogen cycle, perform over 90 percent of all nitrogen fixation.
Oxygen degrades nitrogenases easily. Therefore, in the presence of oxygen, several bacteria avoid producing the enzyme.: Oxygen is this harmful for Nitrogen-fixing bacteria.

Additional Information:
Two types of bacteria fix nitrogen. Cyanobacteria (or blue-green algae) Anabaena and Nostoc and genera like Azotobacter, Beijerinckia, and Clostridium are the first kinds to be free-living (nonsymbiotic) bacteria. The second group is composed of reciprocal (symbiosis) bacteria; Rhizobium, for example, with herbal herbs (e.g. separate pea families), Frankia, with unique dicotyledonous (actinorhizal) species, and certain azospirillum, with cereal herbs.
Symbiotic nitrogen bacteria enter the hair of host plants where root nodules, plant cells, and bacteria are multiplied and stimulated intimately. The bacteria convert free nitrogen to ammonia inside the nodules which the host plant uses to grow. Seeds are normally inoculated with commercial crops of the appropriate rhizobium species, particularly in soils poor or lacking in the necessary bacterial to ensure adequate nodule formation and optimum legume growth (e.g. alfalfa, beans, clovers, peas, soybeans).

So, the correct answer is, “Nitrogen-fixing bacteria”

Note: Bacterium conversion from nitrogen to ammonia is highly costly and oxygen-dependent. The presence of oxygen irreversibly denatured both proteins which constitute nitrogenase. All nitrogenase supporting systems have developed mechanisms to create an atmosphere with low oxygen in nitrogen fixation. By different metabolic processes, oxygen is eliminated from the body.