2What 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.
3The Water CycleMovement of water through the atmosphere, the ground, and bodies of water, and living things is called the water cycle.
4EvaporationEvaporation is the change from a liquid (such as water) to a gas.In the water cycle, evaporation occurs when the sun’s energy warms the water in oceans, lakes and soil.Question: Where does the water vapor go when it is formed?
5TranspirationTranspiration is the process by which living things release water vapor into the atmosphere.Plants and algae release most of the water vapor.
6Quick CheckWhat are two processes that allow water to move into the atmosphere?
7CondensationWho 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?
8PrecipitationPrecipitation 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
10Quick CheckOnce the vapor goes up into the atmos-phere, how does it come back down?
11Carbon CycleAnother 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.
12PhotosynthesisPhotosynthesis 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!)
13Photosynthesis Equation H2O + CO O2 + C6H12O6H2O - waterCO2 - carbon dioxide- from the sun- with green chlorophyllO2 - oxygenC6H12O6 - glucose sugarLIGHT ENERGYLIGHT ENERGY
14PhotosynthesisPhotosynthesis 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.
15Cell Respiration Respiration Respiration returns the carbon from plants and animals to the atmosphere.
16Cell Respiration Equation O2 + C6H12O6ATP ENERGYH2O + CO2+º Cell respiration occurs in the cells of all livingorganisms.º This process keeps it alive by creating energy in aform that the cells can use.º Without this ATP energy, the cell cannot performany of its vital functions (make/acquire food, breakit down, make DNA, reproduce, etc.).
17DecompositionDecomposition 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.
18CombustionCarbon in coal, oil, and natural gas is returned to the atmosphere as carbon dioxide when these fuels are burned.
21Sources of Carbon fromHuman Activity:• Burning wood or forests• Cars, trucks, planes• Burning fossil fuels suchas coal, oil and naturalgas to produce heat andenergy for our homes andbusinessesNatural Sourcesof Carbon:• Death of plants andanimals• Animal waste• Atmospheric CO2• Weathering• Methane gas from cows(and other ruminants)• Aerobic respiration fromterrestrial and aquatic life
22Nitrogen Cycle- movement of nitrogen from the nonliving environment into living things and back again
23Nitrogen CycleAbout 78% of the Earth’s atmosphere is made up of nitrogen gas (N2).All organisms need nitrogen to build protein and DNA , but cannot use N2 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.
24Nitrogen 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.
26PollutionPollution 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.
27Pollution 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.
28Resource DepletionHumans cause environmental problems by using up or depleting natural resources.renewable resources can be used over and over again or has an unlimited supplynonrenewable resources cannot be replaced (or can be replaced, but over thousands or millions of years)
29Check 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.
30Modifications 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?
31Quick Check What is the major reason that the cycles are altered? Give some examples on how humans have changed specifically the nitrogen cycle?
32Why is resource depletion bad for the Earth’s 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.
33Why is resource depletion bad for the Earth’s 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.
34Human Modification of Cycles can affect the balance of: Producer-a photosynthetic organismPrimary Consumer -an animal that eats grass and other producers in a food chain; an herbivoreSecondary Consumer -an animal that feeds on smaller herbivoresTertiary Consumer -an animal that feeds on secondary consumersDecomposer -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 ecosystemAn animal that feeds on secondary consumers in a food chain
35Thought 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?
36Questions for Assessment Describe how human activities have modified soil and water.
37Describe how human activities have modified soil and water Predict results of modifying the Earth’s cycles; water, carbon & nitrogen and show that modification may disrupt the delicate balance of producers, consumers, and decomposers.Modifications:Volcanic eruptionPower plant(burning fossil fuels)Fertilizer run-off
38What if:a volcano erupted causing events of catastrophic proportions; draw and explain how this would affect the Earth’s cycles