Nitrogen fixation a. is the process where nitrogen is converted to a usable form b. is accomplished by plants when they break down soil c. occurs as a result of photosynthesis d. none of the above

a. is the process where nitrogen is converted to a usable form

Explanation:

Nitrogen fixation is a process by which the soil bacteria converts the atmospheric forms of nitrogen such as nitrates, nitrites and ammonia so that these forms can be easily absorbed by the plants and utilized for their growth and development. These forms of nitrogen are used by the plants for the synthesis of proteins which are necessary for cellular metabolism and growth.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

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