cycles in nature section 1: the cycles of matter copyright by holt, rinehart and winston. all...

Cycles in Nature

Section 1: The Cycles of Matter

Copyright © by Holt, Rinehart and Winston. All rights reserved.

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The Cycles of MatterSection 1

Bellringer

What are the three different physical states of water that are found on Earth? Name one way that you use water in each of these states in your daily life.



Objectives• Diagram the water cycle, and explain its importance to living things.

• Diagram the carbon cycle, and explain its importance to living things.

• Diagram the nitrogen cycle, and explain its importance to living things.


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The Water Cycle • How Water Moves During evaporation, the sun’s heat causes water to change from liquid to vapor. In the process of condensation, the water vapor cools and returns to a liquid state. The water that falls from the atmosphere to the land and oceans is precipitation.

• Water and Life Without water, there would be no life on Earth. All organisms, from bacteria to animals and plants, are composed mostly of water.


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The Water CycleSection 1




• Photosynthesis and Respiration Photosynthesis is the basis of the carbon cycle. During photo-synthesis, plants use carbon dioxide from air to make sugars. Carbon returns to the environment through respiration.

• Decomposition and Combustions The breakdown of substances into simpler molecules is called decomposition. Combustion is the process of burning a substance, such as wood or fossil fuels. Decomposition and combustion of organic matter releases carbon dioxide into the atmosphere.

The Carbon Cycle

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The Carbon CycleSection 1




• Converting Nitrogen Gas About 78% of the Earth’s atmosphere is nitrogen gas. Most organisms cannot use nitrogen gas directly. However, bacteria in the soil are able to change nitrogen gas into forms that plants can use.

• Passing It On When organisms die, decomposers break down the remains. Decomposition releases a form of nitrogen into the soil that plants can use. Finally, certain types of bacteria in the soil convert nitrogen to a gas, which is returned to the atmosphere.

The Nitrogen Cycle

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The Nitrogen CycleSection 1




• Converting Nitrogen Gas Other forms of matter on Earth also pass through cycles. Many of the minerals that living cells need, such as calcium and phosphorous, are cycled through the environment.

Many Cycles

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Ecological SuccessionSection 2

BellringerImagine that you have been hired to oversee the maintenance of a public forest. Answer the following questions to describe how you would approach the task:• How would you evaluate the health of the forest?• What actions would you take to keep the forest healthy?• What factors might pose a threat to the health of the forest? How would you prevent these factors from causing harm?

Write your answers in your science journal.


Ecological SuccessionSection 2

Objectives• Describe the process of succession.

• Contrast primary and secondary succession.

• Explain how mature communities develop.


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Cycles in NatureChapter 19

Concept Map


Use the following terms to complete the concept map on the next slide: water cycle, precipitation, decomposition, carbon, combustion, condensation, carbon cycle, photosynthesis.

cycles in nature section 1: the cycles of matter copyright by holt, rinehart and winston. all...

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