Cycling of Matter


Recall that all matter is constructed from atoms, which take up space and have mass. In nature, matter is not destroyed; it is either transformed into different types of matter or moved from one location to another in processes we call cycles. Think of a piece of gum stuck on a bicycle wheel. It begins at one point, travels to different positions in space, but it eventually returns back to the same point. Something similar to this process happens in nature. The atoms inside your body are billions of years old, having traveled through space, soil, rock, water, air, and other living organisms. In fact, it is likely that some matter inside your body was once found in a dinosaur...or its poop. Just imagine what the world would be like if matter was not recycled by nature: the ground would be littered with dead organisms resting atop their waste. It's not a pretty picture, but more importantly it is not an environment that can continually support life. Thankfully, their are organisms and processes in nature that transform the waste created by some organisms into useful forms of matter. In this section, we will investigate three different cycles: the carbon cycle, the nitrogen cycle, and the water cycle.

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7.5B demonstrate and explain the cycling of matter within living systems such as in the decay of biomass in a compost bin. (Spiraling TEKS)
7.6A identify that organic compounds contain carbon and other elements such as hydrogen, oxygen, phosphorus, nitrogen, or sulfur. (Spiraling TEKS)


Aquifer: An area of rock located underground capable of holding or transporting water.
Bacteria: Single celled organisms that often act as decomposers; bacteria can be either autotrophs or heterotrophs
Coal: a type of rock formed by the decay of organic matter; coal is commonly burnt to generate energy Compost: decayed plant material; people often recycle plant waste in compost bins.
Condensation: a physical change in matter from gasous to liquid state
Decay: the decomposition of organic matter
Denitrification: the production of nitrogen gas (N2) using other nitrogen compounds; in this process nitrogen moves from the soil into the air.
Evaporation: a physcial change in matter from liquid to gaseous state; opposite of condensation
Fertilizer: a substance that provides additinal nutrients for plants; often contains high levels of nitrogen (N).
Gas Exchange: the movement of gases from one area into another; for example, from air to water.
Limestone: a type of rock formed from the hard parts (e.g. bones and shells) of dead organisms
Nitrogen Fixation: the production of nitrogen compounds using nitrogen gas (N2); during this process, nitrogen moves from the air into the soil.
Oil: an organic liquid formed by the decomposition of organic matter.
Organic Compound or Matter: compounds made up of Carbon and at least 1 Hydrogen atom; often includes other atoms like sulfur, phosphorous, nitrogen, and oxygen.
Precipitation: occurs when the product of condensation falls to due to gravity
Transpiration: the loss of water from plants; similar to evaporation