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Multiple Choice
Nitrogen gas ($N_2$) becomes converted into biologically usable chemical forms by what type of organism?
A
Nitrogen-fixing bacteria
B
Green algae
C
Fungi
D
Protozoa
Verified step by step guidance
1
Understand the process of nitrogen fixation: Nitrogen fixation is the conversion of atmospheric nitrogen gas ($N_2$) into ammonia ($NH_3$) or other biologically usable forms. This process is essential for making nitrogen available to living organisms, as most cannot use $N_2$ directly.
Identify the organisms capable of nitrogen fixation: Nitrogen fixation is primarily carried out by specialized microorganisms known as nitrogen-fixing bacteria. These bacteria possess the enzyme nitrogenase, which facilitates the conversion of $N_2$ into ammonia.
Learn about symbiotic relationships: Some nitrogen-fixing bacteria, such as Rhizobium, form symbiotic relationships with plants (e.g., legumes). They live in root nodules and provide the plant with usable nitrogen in exchange for carbohydrates.
Differentiate nitrogen-fixing bacteria from other organisms: Green algae, fungi, and protozoa do not have the ability to fix atmospheric nitrogen into biologically usable forms. This function is unique to nitrogen-fixing bacteria and certain archaea.
Conclude that nitrogen-fixing bacteria are the correct answer: Based on the biological process and the organisms involved, nitrogen-fixing bacteria are responsible for converting $N_2$ into usable chemical forms.