Short Answer Questions
1. What is biological fixation of nitrogen? How does it differ from chemical fixation of
nitrogen?
2. Write a short note on nutrient cycle in aquatic ecosystem.
4. Write balanced chemical equations involved in chemical fixation of nitrogen.
a. Why does the concentration of toxic substances increase from a lower to a higher trophy
level?
Answers
Answer:
1.Biological nitrogen fixation (BNF) is the term used for a process in which nitrogen gas (N2) from the atmosphere is incorporated into the tissue of certain plants. Only a select group of plants is able to obtain N this way, with the help of soil microorganisms.
2.In nature, however, terrestrial, freshwater, and marine systems are all connected by nutrient flows. Currently, human activities strongly influence nutrient cycles by removing nutrients from the land and discharging them into aquatic environments, leading to eutrophication of water sources.
4.The initial step of this process, known as nitritation, involves a type of bacteria called nitrosomonas. During nitritation, nitrosomonas convert NH3 (ammonia) into NO2 (nitrogen dioxide). The chemical equation for this process is NH3 + 1.5 O2 --> NO2- + H+ + H20.
a.Bioaccumulation is the process by which toxins enter the food web by building up in individual organisms, while biomagnification is the process by which toxins are passed from one trophic level to the next (and thereby increase in concentration) within a food web.
Explanation:
Hope it helps....If it helps, please mark it as the brainliest answer.