AP BIOLOGY

ECOLOGY

CHEMICAL CYCLES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Converting atmospheric nitrogen into a usable form by bacteria or lightning is known as ____
A
nitrogen fixation
B
denitrification
C
ammonification
D
assimilation
Explanation: 

Detailed explanation-1: -Nitrogen is converted from atmospheric nitrogen (N2) into usable forms, such as NO2-, in a process known as fixation. The majority of nitrogen is fixed by bacteria, most of which are symbiotic with plants. Recently fixed ammonia is then converted to biologically useful forms by specialized bacteria.

Detailed explanation-2: -Fixation. Nitrogen in its gaseous form (N2) can’t be used by most living things. (Plants for example, do not have the required enzymes to make use of atmospheric nitrogen.) It has to be converted or ‘fixed’ to a more usable form through a process called fixation.

Detailed explanation-3: -Biological nitrogen fixation or diazotrophy is an important microbe-mediated process that converts dinitrogen (N2) gas to ammonia (NH3) using the nitrogenase protein complex (Nif).

Detailed explanation-4: -Lightning can also fix nitrogen. The high temperature of a lightning bolt can break the bonds of atmospheric nitrogen molecules. Free nitrogen atoms in the air bond with oxygen in the air to create nitrogen oxides, which dissolve in moisture to form nitrates that are carried to Earth’s surface by precipitation.

Detailed explanation-5: -Nitrogen Fixation For nitrogen to be available to make proteins, DNA, and other biologically important compounds, it must first be converted into a different chemical form. The process of converting N2 into biologically available nitrogen is called nitrogen fixation.

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