65. What plays multiple roles in the cycling of nitrogen, including converting nitrogen gas into a form of nitrogen usable by plants?
Answer: C
Bacteria play multiple roles in the cycling of nitrogen, including converting nitrogen gas into a form of nitrogen usable by plants.
Bacteria are essential in the nitrogen cycle, particularly in the process of nitrogen fixation, where they convert atmospheric nitrogen gas (N₂) into ammonia (NH₃), which plants can utilize. This function is crucial for maintaining soil fertility and supporting plant growth.
A) Animals
Animals do not play a direct role in the conversion of nitrogen gas into a usable form for plants. Instead, they rely on plants for nitrogen, primarily through consuming plant matter. While animals contribute to the nitrogen cycle through processes such as excretion, they do not perform nitrogen fixation.
B) Lightning
Lightning does facilitate the conversion of nitrogen gas into nitrates through the intense heat and energy it generates during storms. However, this is a less significant process compared to biological nitrogen fixation carried out by bacteria, which directly provides usable nitrogen to plants in the soil.
C) Bacteria
Bacteria are the primary agents in the nitrogen cycle, especially in nitrogen fixation. Certain types of bacteria, such as Rhizobium, form symbiotic relationships with leguminous plants and convert atmospheric nitrogen into ammonia, making it accessible for plant uptake and growth. This role is fundamental to the nitrogen cycle.
D) Fungi
Fungi are important decomposers in ecosystems and contribute to nutrient cycling, but they do not convert nitrogen gas into a usable form for plants. Their role is more related to breaking down organic matter to release nitrogen in forms that can be utilized by plants, rather than fixing atmospheric nitrogen.
Conclusion
Bacteria are the key players in nitrogen fixation, converting nitrogen gas into ammonia, which plants can absorb and use. While animals, lightning, and fungi have their respective roles in the nitrogen cycle, they do not fulfill the specific function of converting atmospheric nitrogen into a biologically usable form, making bacteria the definitive answer.