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 as they facilitate the conversion of atmospheric nitrogen gas into ammonia through a process known as nitrogen fixation. This process makes nitrogen available to plants, which is crucial for their 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 indirectly, as they consume plant material that contains nitrogen compounds. Therefore, while animals contribute to the nitrogen cycle through waste and decomposition, they do not convert nitrogen gas themselves.
B) Lightning
Lightning contributes to nitrogen cycling by converting nitrogen gas in the atmosphere into nitrates through a process called atmospheric fixation. However, this process is relatively minor compared to the role of bacteria. While nitrates produced by lightning can be used by plants, it is not the primary means through which nitrogen gas is converted into usable forms.
C) Bacteria
Bacteria are the primary agents in the nitrogen cycle, specifically through the processes of nitrogen fixation and nitrification. They convert nitrogen gas from the atmosphere into ammonia, which is then further processed into nitrates, making nitrogen accessible to plants. This role is vital for maintaining the ecosystem's nitrogen balance.
D) Fungi
Fungi play a supportive role in the nitrogen cycle, primarily through decomposition and nutrient cycling. They help break down organic matter, releasing nitrogen back into the soil, but they do not convert nitrogen gas into a usable form for plants. Thus, their role is not directly related to the initial conversion of atmospheric nitrogen.
Conclusion
Bacteria are the key players in the nitrogen cycle, particularly in the conversion of nitrogen gas into ammonia and nitrates that plants can utilize. While animals, lightning, and fungi all have roles within the nitrogen cycle, they do not directly perform the critical function of nitrogen fixation as bacteria do. This highlights the essential nature of bacteria in supporting plant life and sustaining the ecosystem.