Answer:
Option A, Nitrogen is essential for growth in producers.
Explanation:
Nitrogen is one of the critical limiting element which is essential for the plant growth and production.
The major component of chlorophyll is nitrogen and hence is an important pigment for photosynthesis. It is also a building block of protein, biomolecules, such as ATP and nucleic acids
Plants take nitrogen
1) through ammonia or nitrate fertilizer
2) Nitrogen released by the decomposition of organic matter
3) conversion of atmospheric nitrogen into useful organic compounds
4) biological nitrogen fixation
Thus, when a lake gets excess of nitrogen , algal boom occurs (due to their increased productivity)
Biological nitrogen fixation (BNF), discovered by Beijerinck in 1901 (Beijerinck 1901), is carried out by a specialized group of prokaryotes. These organisms utilize the enzyme nitrogenase to catalyze the conversion of atmospheric nitrogen (N2) to ammonia (NH3). Plants can readily assimilate NH3 to produce the aforementioned nitrogenous biomolecules. These prokaryotes include aquatic organisms, such as cyanobacteria, free-living soil bacteria, such as Azotobacter, bacteria that form associative relationships with plants, such as Azospirillum, and most importantly, bacteria, such as Rhizobium and Bradyrhizobium, that form symbioses with legumes and other plants (Postgate 1982). These organisms are summarized in Figure 1
