Cycles in Nature Science 7 Chapter 19 Cycles in Nature Science 7

Section 1: The Cycles of Matter

Matter: Anything that takes up space and has mass. The matter that makes up your body has been on earth for billions of years. All matter is recycled and used over and over again.

The Water Cycle The movement of water among the oceans, atmosphere, land, and living things.

Precipitation Water that moves from the atmosphere to the ground. It includes rain, snow, sleet, and hail. 91% of precipitation falls into the ocean.

Evaporation Water moving back up into the atmosphere. The sun’s heat causes the water to change from liquid to vapor. When this vapor cools, it condenses and then falls back to Earth.

Ground Water Precipitation that seeps into the ground, where it is stored for thousands of years. (Unless we use it.)

Water and Life All organisms contain water. You are made of 70% water. Water carries waste products away from body tissues. It also helps regulate water temperature.

The Carbon Cycle The movement of carbon from the environment into living things and back into the environment again.

Photosynthesis The process by which carbon cycles from the environment into living things.

Respiration The sugar made from photosynthesis is broken down to release energy. Carbon dioxide and water are then released.

Decomposition The breakdown of dead materials into carbon dioxide and water. Fungi and bacteria do this and then it returns carbon to the environment.

Combustion  Carbon in coal, oil, and natural gas returns to the atmosphere as carbon dioxide when they are burned.

The Nitrogen Cycle The movement of nitrogen from the environment to living things and back again.

Nitrogen Fixation As animals we need nitrogen to make proteins and DNA. Our atmosphere is made of about 78% nitrogen. However we cannot use this nitrogen the way it is. So, bacteria in the soil change this nitrogen so that plants can us it. We then get nitrogen by eating plants.

Another type of bacteria that live in the soil, break down dead organisms and waste. This process produces nitrogen gas which is returned to the atmosphere.

Ecological Succession The gradual development of a community over time. Ex. The regrowth of the burned area at Yellowstone National Park.

Primary Succession When the life of a community is completely wiped out from glaciers or volcanoes. Stage 1: The beginning, no life exists. Stage 2: Acid from lichens begin breaking the rocks into small particles. These particles mix with the remains of dead lichens and form soil. Because lichens are the first living organisms, they are called Pioneer species. Stage 3: After many years, the soil gets deep enough to support mosses, which replace the lichens. Stage 4: Eventually the mosses are replaced by ferns, shrubs and small trees grow. Stage 5: After hundreds or thousands of year enough soil has accumulated to support a forest.

Secondary Succession When a community is destroyed by natural disaster, such as fire or flood. Stage 1: Crabgrass begins to grow. Stage 2: By the second year, new weeds appear Stage 3: In 5 to 15 years, small pine trees grow, after about 100 years, a forest may form. Stage 4: As older pines die, they are replaced by hardwoods if the climate can support them.

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