Question

Which statement about nitrogen fixation is false?

(a) it is energetically expensive.
(b) legumes are examples of plants that use nitrogen-fixing bacteria.
(c) it is more common in late succession than in early succession.
(d) it often results in trade-offs in growth and/or reproduction.

Answer 1

The false statement about nitrogen fixation is that nitrification by bacteria converts nitrates to nitrites. Nitrification actually converts ammonia into nitrites and then nitrates, aiding in the nitrogen cycle.

Step-by-step explanation:

The false statement about nitrogen fixation is "c. Nitrification by bacteria converts nitrates (NO3-) to nitrites (NO2)". Nitrification is actually the process in which bacteria convert ammonia (NH4+) into nitrites (NO2-) and then into nitrates (NO3-), not the other way around. This is a key step in the nitrogen cycle that helps make nitrogen available to plants in a form they can use. Moreover, denitrification is the process in which denitrifying bacteria convert nitrates (NO3-) back into nitrogen gas (N2), thus completing the cycle.

Legumes partner with nitrogen-fixing bacteria, such as rhizobia, to obtain nitrogen from the atmosphere, converting it into a form that the plants can use for growth. Through symbiotic nitrogen fixation, both the bacteria and the plant benefit: the bacteria from the carbohydrates produced by the plant through photosynthesis, and the plant from a consistent source of usable nitrogen.