The incorrect statement about the nitrogen cycle is option A: nitrate and nitrite reductases in denitrifying bacteria convert ammonia to nitrogen gas.
The biological nitrogen fixation (BNF) is the process by which atmospheric nitrogen is changed into ammonia, and the nitrogen-fixing bacteria are known as diazotrophs. Fixation, ammonification, nitrification, and denitrification are significant nitrogen cycle processes. Ammonia is converted to nitrites and then to nitrates which are absorbed by plants with the help of their roots. Therefore, option A is incorrect.
Through bacteria that fix nitrogen from the atmosphere, nitrogen enters the living world. Soil bacteria convert this nitrogen and nitrogenous animal waste back into gaseous nitrogen, supplying the organic nitrogen required by terrestrial food webs.
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Answer: Smallpox
Explanation: Small pox is an ancient disease which is caused by the Virus named as Variola virus. Early symptoms are fatigue and high fever.
The virus then after produces rash on faces arms and legs. The spots gets filled with fluid and pus and in later stages it turned into crust.
This crust eventually dried and falls off. It was fatal in almost 30% of the cases.
It eradicated by a collaborative global vaccination program which was led by WHO.
I think it is C because i got this same exact question in my class