All organisms need a source of nitrogen and other matter. Explain how the nitrogen and other matter in your body came from other living things and the environment.

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.

b. to discover aspects of the natural world.

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