SEARCH
You are in browse mode. You must login to use MEMORY

   Log in to start


From course:

Oceanography L6-10

» Start this Course
(Practice similar questions for free)
Question:

Nitrogen fixation in the sea

Author: Alex Rapai



Answer:

N cycle includes a gaseous phase (N2) which is fixed into biologically available ammonium by nitrogen fixation. The atmosphere provides a large potential reservoir of N. Generally N2 fixation rates are low and there are few N2 fixing organisms. In cyanobacteria nitrogenase is usually found in heterocysts (specialised cells, lacking PSII activity & hence anaerobic); or temporal separation of N2-fixation & photosynthesis. N2 -fixation genes are dispersed throughout the prokaryotic kingdom. Factors that might limit the genetic potential & expression of N2-fixation in the marine environment : i) the large energy & reductant requirement, ii) sensitivity of nitrogenase to inactivation by O2, iii) repression of nitrogenase activity by fixed nitrogen e.g nitrate, ammonia iv) the requirement for micronutrients such as molybdenum, vanadium & iron


0 / 5  (0 ratings)

1 answer(s) in total