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Science 1

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What is a cycle? A cycle is a series of repeating events. Examples? The most important cycles for living things involve water, carbon and nitrogen. In all of these cycles, matter moves continuously through the atmosphere, the land, and living things. 2

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The Water Cycle Movement of water through the atmosphere, the ground, and bodies of water, and living things is called the water cycle. 3

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Evaporation Evaporation is the change from a liquid (such as water) to a gas. In the water cycle, evaporation occurs when the suns energy warms the water in oceans, lakes and soil. Question: Where does the water vapor go when it is formed? 4

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Transpiration Transpiration is the process by which living things release water vapor into the atmosphere. Plants and algae release most of the water vapor. 5

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Quick Check What are two processes that allow water to move into the atmosphere? 6

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Condensation Who has seen a sweating glass of ice water before? Condensation is the process by which water vapor changes from a gas to a liquid. This change occurs when the water vapor cools, which creates the liquid again. When have we seen this happen? 7

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Precipitation Precipitation includes rain, snow, sleet, & hail. -water moves from the atmosphere to the land and the ocean as precipitation - this precipitation seeps into the ground, where it is stored in underground caverns or in porous rock -groundwater supplies water to soil, streams, rivers, and oceans 8

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Water Cycle 9 Condensation

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Quick Check Once the vapor goes up into the atmos- phere, how does it come back down? 10

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Carbon Cycle Another cycle that is very important to all organisms on Earth is the carbon cycle. Since all living things are made up of molecules that contain carbon, this cycle is very important. Carbon cycle is the movement of carbon from the nonliving environment into living things and back. 11

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Photosynthesis Photosynthesis is the process by which plants use carbon dioxide from the air to make sugars. Most animals get the carbon they need by eating plants. (Carbon bonds store energy allowing living organisms to move, eat, sleep, breath and repair so important!) 12

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Photosynthesis Equation H 2 O + CO 2 + O 2 + C 6 H 12 O 6 H 2 O - water CO 2 - carbon dioxide - from the sun - with green chlorophyll O 2 - oxygen C 6 H 12 O 6 - glucose sugar LIGHT ENERGY 13

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Photosynthesis Photosynthesis usually occurs in the leaves of plants, specifically in the chloroplasts of each cell. Do root cells have chloroplasts? Only plants, algae, some protists, and some bacteria are photosynthetic producers. Animals, fungi, and other protists and bacteria are consumers. They are not photosynthetic.

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Cell Respiration Respiration Respiration returns the carbon from plants and animals to the atmosphere. 15

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Cell Respiration Equation O 2 + C 6 H 12 O 6 H 2 O + CO 2 ATP ENERGY + Cell respiration occurs in the cells of all living organisms. This process keeps it alive by creating energy in a form that the cells can use. Without this ATP energy, the cell cannot perform any of its vital functions (make/acquire food, break it down, make DNA, reproduce, etc.).

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Decomposition Decomposition is the breakdown of dead organisms and organic wastes, which releases carbon dioxide. Ex. When fungi and certain bacteria decompose organic matter, they return carbon to the soil and air. 17

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Combustion Carbon in coal, oil, and natural gas is returned to the atmosphere as carbon dioxide when these fuels are burned. 18

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The Carbon Cycle 19

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21 Natural Sources of Carbon: Death of plants and animals Animal waste Atmospheric CO2 Weathering Methane gas from cows (and other ruminants) Aerobic respiration from terrestrial and aquatic life Sources of Carbon from Human Activity: Burning wood or forests Cars, trucks, planes Burning fossil fuels such as coal, oil and natural gas to produce heat and energy for our homes and businesses

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Nitrogen Cycle - movement of nitrogen from the nonliving environment into living things and back again 22

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Nitrogen Cycle About 78% of the Earths atmosphere is made up of nitrogen gas (N 2 ). All organisms need nitrogen to build protein and DNA, but cannot use N 2 as it is. Nitrogen fixation- nitrogen is changed into a usable form by certain bacteria in plant roots and soil (usable forms = ammonia, nitrates, nitrites) Then, as animals eat plants they get the usable nitrogen. 23

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Nitrogen Cycle - key points Some bacteria help get usable nitrogen ready for animals. Other types of bacteria help return the nitrogen to the atmosphere. These bacteria break down dead organisms and animal wastes. 24

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Nitrogen cycle 25

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Pollution Pollution is the presence of dangerous levels of substance in the environment. The pollutants might be a solid, chemical, gas, or even energy. When they enter the cycles, they disrupt the normal cycles. 26

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Pollution Over time human activities have altered the cycles. How? Pollution from our busy lives has affected our soil, water, and air quality. We are using resources faster than they can be replaced. 27

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Resource Depletion Humans cause environmental problems by using up or depleting natural resources. renewable resources can be used over and over again or has an unlimited supply nonrenewable resources cannot be replaced (or can be replaced, but over thousands or millions of years) 28

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Check for Understanding What would happen to the water cycle, carbon cycle, and nitrogen cycle if most of the land on Earth were paved? Predict what would happen if scientists would develop a crop with more nitrogen fixing bacteria in their roots. 29

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Modifications of Earth Cycles What are some things that alter the cycles? Do these changes alter just one cycle or can they affect all of the cycles? 30

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Quick Check What is the major reason that the cycles are altered? Give some examples on how humans have changed specifically the nitrogen cycle? 31

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Why is resource depletion bad for the Earths cycles? If soil erosion continues, then the cycles will not continue the same. -water washes away soil, what are the causes? If air continues to be polluted, the cycles will not convert the air as before and C and N levels released will not be the same. 32

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Why is resource depletion bad for the Earths cycles? Habitat destruction is another way humans have modified air quality, soil, and water on Earth. Our pollution is affecting where organisms live. Forests and wetlands have been altered and affected by our pollution. These changes have really affected the cycles of the Earth and will continue to alter the cycles. 33

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Human Modification of Cycles can affect the balance of: Producer-a photosynthetic organism Primary Consumer -an animal that eats grass and other producers in a food chain; an herbivore Secondary Consumer -an animal that feeds on smaller herbivores Tertiary Consumer -an animal that feeds on secondary consumers Decomposer -an organism, often a bacterium or fungus, that feeds on and breaks down dead plant or animal matter, thus making organic nutrients available to the ecosystem 34

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Thought Questions -relate all answers to cycles- What will happen if trees are not being replaced when used? What will happen if soil erosion occurs? What will happen to the nitrogen cycle if there are fewer healthy plants? What will happen if nitrogen fixing bacteria are not present? 35

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Questions for Assessment Describe how human activities have modified soil and water. 36

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Describe how human activities have modified soil and water 37 Predict results of modifying the Earths cycles; water, carbon & nitrogen and show that modification may disrupt the delicate balance of producers, consumers, and decomposers. Modifications: Volcanic eruption Power plant (burning fossil fuels) Fertilizer run-off

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What if: a volcano erupted causing events of catastrophic proportions; draw and explain how this would affect the Earths cycles 38