Nitrogen Fixation Quiz and Flashcards: Essential Element of Life

Study Notes

Nitrogen Fixation and Its Importance

Nitrogen is a required component for chlorophyll molecules to form in plants, and without it, plants cannot produce chlorophyll, photosynthesize, or produce their own food.
Nitrogen-fixing bacteria develop a symbiotic connection with plants in a mutually beneficial relationship called mutualism.
The chemical formula for nitrogen fixation is the transformation of atmospheric nitrogen into ammonia.

The Nitrogen Cycle

The nitrogen cycle consists of five steps: biological nitrogen fixation, nitrification, ammonification, assimilation, and denitrification.
Biological nitrogen fixation: Atmospheric nitrogen is transformed into ammonia by free-living prokaryotic organisms in the soil or mutualistic bacteria in the roots of plants.
Nitrification: Prokaryotic nitrifying bacteria in the soil further convert ammonia into nitrates and nitrites.
Ammonification: A natural process that occurs when nitrogen-containing compounds are returned to the soil via animal waste products or from dead, decomposing organisms.
Assimilation: Bioavailable nitrogen is absorbed by eukaryotic organisms in the soil like plants.
Denitrification: Some microorganisms take bioavailable nitrogen and transform it back into nitrogen gas, which is returned to the atmosphere.

Why Nitrogen Fixation is Important

Nitrogen fixation is a vital biochemical step in the nitrogen cycle, without which plants and animals could not grow.
Plants are primary producers, creating food from sunlight by photosynthesis, and are dependent on nitrogen-fixing bacteria and archaea for their metabolic and biological needs.
Nitrogen is used not only for chlorophyll but for many other cellular and reproductive processes that involve proteins and DNA.

Nitrogen Fixation in Ecosystems

Nitrogen fixation is essential for ecosystems, as it moves nitrogen from the air into the soil where it is transformed by prokaryotes into bioavailable forms for plants and animals.
Human beings require nitrogen for the proteins and DNA in their bodies, and obtain it through dietary sources.
Nitrogen fixation is necessary for agricultural systems, as it provides the necessary nitrogen for crop growth.

Nitrogen Fixation Examples

Terrestrial nitrogen fixation examples involve mutualistic bacteria like Rhizobium, which forms nodules on the roots of legumes like beans, lentils, and clover.
Marine nitrogen fixation examples involve free-floating diazotrophic microorganisms, like cyanobacteria, that fix atmospheric nitrogen into bioavailable forms.

Description

Discover the importance of nitrogen fixation, the process by which gaseous nitrogen is converted into a bioavailable form, essential for plants and animals to build proteins and maintain life functions. Learn about the role of microorganisms in this vital process.