BIOGEOCHEMICAL CYCLES WORKSHEET Objectives: 1. Explain how certain biogeochemical cycles work. 2. Identify how humans are impacting the biogeochemical cycles. 3. Recognize the parts of each cycle. A BIOGEOCHEMICAL CYCLE is a circuit, or ______________________, by which an element or molecule moves through both _______________ and _________________ components of an ecosystem. We will study the following biogeochemical cycles: Water Carbon Nitrogen Phosphorous Water Cycle Water is the basic building block of ______________________ on Earth. Water regulates the ___________________ of the planet and cycles essential _____________________ through the biosphere and all living things. The flow of water through the biosphere is called the ____________________. Important Vocabulary: Condensation Precipitation Evaporation Transpiration Condensation: The transformation of water ______________ to ______________ water droplets in the air, producing clouds and fog is known as ____________________________. Precipitation: ________________ water vapor that falls to the Earth's surface is __________________. Most precipitation occurs as rain, but also includes snow, hail, and sleet. Evaporation: ____________________ is the process by which liquid water is _____________ by the ___________________ and rises into the atmosphere as __________ ______________. Transpiration: ______________________ is the ___________________ of water from the ______________________ of plants. Remember This!!! Water enters the atmosphere through evaporation and transpiration. Transpiration is the evaporation of water from plants. Water returns to the Earth through precipitation. Interesting Scientific Fact Changing the solid form of water (ice) to the liquid state of water requires heat. Changing water back into ice gives off heat. Knowing this, orange farmers in southern states spray their orange trees with water to prevent them from freezing during sudden cold snaps. The way it works is simple. As the water begins to freeze on the orange trees, it gives off heat which then prevents the fruit from freezing. The crop is saved. Question #1. How does water return to the Earth? Question #2. What is transpiration? Question #3. How does water enter the Earth's atmosphere? Carbon Cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the ___________________________ and ______________________________. Carbon is an essential component of ______________________, _______________, and __________________________ which make up all living organisms. Important Vocabulary: Cellular Respiration Photosynthesis Decomposition Combustion Fossil Fuels 1. 2. 3. Carbon exists in the Earth's atmosphere primarily as the gas ______________ _________________________. (_______) Carbon is taken _______________ the _______________________ and returned to the Earth by the process ______________________________. Carbon can be released back into the atmosphere in many different ways, including: - Remember Photosynthesis? Plants take ______________________ from the _____________________, combine it with light energy and water to produce glucose and oxygen. CO2 + H2O + light energy -----------> C6H12O6 + O2 (_______________) + (_____________) -----> (______________) + (________) Remember Cellular Respiration? Cellular Respiration, performed by ______________ plants and animals, involves the breaking down of __________________ into _______________________ and water. C6H12O6 + O2 -----> CO2 + H2O (________________) + (_____________) ------> (__________________) + (_________) • The ____________________________ is then released back into the atmosphere. Decomposition: _____________________ is returned to the Earth and released into the atmosphere through the ______________________ of plants and animals. _____________________, such as fungi and bacteria, break down the carbon compounds in dead animals and plants and convert the carbon into _______________ • ________________________ in the presence of oxygen, or methane if oxygen is not present. Combustion: ____________________________ is the burning of _____________________ such as coal, oil, and natural gas. Combustion ________________________ carbon that has been stored in the Earth’s crust for millions of years into the atmosphere as ___________ _____________________________. Interesting Scientific Fact!!! When some prehistoric plants died, they became buried over time by layers of the Earth. During that time, they were changed into fossil fuels such as coal and oil. The carbon contained in those once living organisms is burned as a fuel for cars. That same carbon is then released into the atmosphere. The carbon went from being a part of a plant to being released into the atmosphere as carbon dioxide. How Humans Affect the Carbon Cycle: ____________________ (burning fossil fuels) - Driving their cars a lot. Deforestation (destroying vegetation that _______________ carbon dioxide) Remember This!!! Carbon enters the atmosphere through cellular respiration. Carbon is absorbed from the atmosphere through photosynthesis. Humans have GREATLY impacted the carbon cycle by putting more carbon dioxide into the atmosphere through combustion than what is removed by photosynthesis. Question #4. How does carbon enter the atmosphere? Question #5. How is carbon removed from the atmosphere? Question #6. How does carbon enter living organisms? Question #7. How are humans impacting the carbon cycle and what is one of the results from human impact? Nitrogen Cycle The nitrogen cycle is the _________________________________ by which nitrogen is exchanged between the biosphere and living organisms. The Earth’s atmosphere is about _________________; however, it is in the form of nitrogen gas and is ___________________ by most living organisms. ● Nitrogen fixing bacteria “fix” or change the nitrogen ________ from the atmosphere into a usable from for living organisms. Nitrogen Cycle Important Vocabulary: Legumes ________ __________ Nitrogen Fixing Bacteria Nitrogen Cycle ● Nitrogen in the _____________________ is unusable to plants and ________. ● In order for nitrogen gas to be usable, it needs to be “_________________” Nitrogen-fixing bacteria creates usable forms. __________________ also “fixes” atmospheric ___________. Nitrogen-Fixing Bacteria: ________________________ Nitrogen-fixing bacteria, there would __________ be enough usable nitrogen available to living organisms. - ___________________________ “fix” or ________________________ the nitrogen _______ from the atmosphere into a _______________ form for living organisms. Nitrogen-fixing bacteria __________ on the ______________ of ________________. - Legume plants include: The legumes provide ______________ for the bacteria while the bacteria provide _____________________ to the plant. Human Impacts on the Nitrogen Cycle: ______________________ global concentrations of nitrous oxide (N2O) creates ________________________________. Increased use of ____________________ increases the nitrogen runoff into our waterways and contributes to ____________________________. Remember This!!! Atmospheric nitrogen (gas) is unusable by most living organisms. Nitrogen-fixing bacteria provide most of the usable nitrogen. Nitrogen-fixing bacteria are found on the root nodules of legumes. Question #8. Where is most nitrogen found? Question #9. Where does usable nitrogen come from? Question #10. What type of relationship exists between nitrogen-fixing bacteria and legumes? Phosphorous Cycle The phosphorous cycle may also be referred to as the _____________ cycle. The phosphorous cycle is the movement of phosphorous from the _____________ to _____________________ and then back to the ______________________. Phosphorous is mainly found in _______________, ____________. and _________. Phosphorous is essential for life. - Component of _________________ - Building block of our __________________ and ____________________. Unlike the other cycles, phosphorous ________ be found in________ in the gaseous state. The phosphorous cycle is the ______________________ cycle. Phosphorous is most commonly found in ____________ formations and ocean sediments as phosphate salts. Phosphate salts that are released from the rocks through __________________ usually dissolve in soil water and will be absorbed by plants. ______________ absorb phosphates by ______________ plants or plant-eating animals. When animals and plants die, phosphates will return to the soils or ocean again during ___________________________. After that, phosphorous will end up in sediments or rock formations again, remaining there for millions of years. Eventually, phosphorous is released again through weathering and the cycle starts over. Human Impact on the Phosphorous Cycle: Like nitrogen, increased use of ______________________ increases phosphorous runoff into our waterways and contributes to ____________________________. Remember This!!! Most phosphorous is found in rocks and soil. The phosphorous cycle is the slowest cycle. Excess phosphorous contributes to eutrophication. Question #11. Where is most phosphorous found? Question #12. What is phosphorous used for in humans?
