Unit 18 Notes and Study Links

Unit 18 Biogeochemical Cycles CONCISE Notes

Unit 18 Flashcards:

-Organisms must have the elements carbon, hydrogen, oxygen, and nitrogen in a form that cells can use. -These elements are found in the biosphere – part of the earth where living things are found – land, air, water. -Biogeochemical cycles - the movement of elements and compounds through ecosystems -The water cycle, carbon cycle, oxygen cycle, and nitrogen cycle move these elements from nonliving to living parts of the ecosystem.
The Water Cycle
Evaporation -water from lakes, streams, rivers, other bodies of water becomes water vapor and enters the atmosphere	Transpiration -Plants release water vapor into the atmosphere through stomata - openings on the bottom of a leaf -Guard cells control the amount of water that leaves the cell	Condensation -Water vapor from evaporation and transpiration cool and become clouds	Precipitation -water moves from atmosphere to ground in the form of rain, sleet, hail, snow	Groundwater -Ground water sinks beneath the earth’s  surface but may eventually reaches lakes and oceans Runoff - water that travels from ground surfaces to lakes, rivers, oceans

The Carbon Cycle -Carbon is the building block of organic molecules, making up fats, proteins, and carbohydrates -Carbon in the atmosphere is in the form of carbon dioxide (CO2) Decomposers break down dead organisms and release carbon dioxide into the air and nitrogen into the soil -Some of the carbon from dead organisms gets trapped in the ground and becomes fossil fuels -Combustion - the process of burning fuels that releases carbon dioxide into the air; -Decomposition - the process of breaking down organic materials into simpler substances into the soil -Burning fossil fuels releases carbon dioxide back into the air -clear-cutting forests reduced the number of trees that can remove carbon dioxide from the air
Photosynthesis (Carbon Fixation) -Photosynthesis takes carbon dioxide out of the air -occurs in the leaves of plants -changes carbon dioxide into carbohydrates -carbohydrates - sugars made by plants -uses water and carbon dioxide to produce glucose and oxygen -carbon fixation - changing carbon dioxide into sugars  -  so that organisms can get energy - changing inorganic carbon into organic carbon - this is what photosynthesis does		Cellular Respiration -Cellular respiration puts carbon dioxide into the air -changes the carbon in simple sugars and carbohydrates back into carbon dioxide in the atmosphere, releasing the energy. -Plants and animals use some of this energy -animals eat plants or other animals to get carbon from the carbohydrates made by photosynthesis

The Oxygen Cycle -Similar to the carbon cycle - it involves photosynthesis and cellular respiration -involves photosynthesis and cellular respiration -most of earth’s oxygen is found in the the earth’s crust as in compounds such as aluminum oxide
Photosynthesis -water molecules are split releasing oxygen into the air as a byproduct -Some oxygen is found as ozone – O3 - 3 oxygen molecules -blocks ultraviolet radiation from the sun		Cellular Respiration -oxygen is used by living organisms during cellular respiration in the mitochondria to make ATP, the energy of the cell -the oxygen is released as part of carbon dioxide and taken in again by producers

The Carbon - Oxygen Cycle -The Carbon - Oxygen Cycle combines the carbon cycle and the oxygen cycles together. -It includes photosynthesis, cellular respiration, combustion, and decomposition. The carbon oxygen cycle is the process by which plants use carbon dioxide for respiration during photosynthesis and produce oxygen. During this process, carbon dioxide becomes part of the plant, and when the plant dies in a carbon-rich state it is possible for it to become a fossil fuel.

The Nitrogen Cycle -Nitrogen is a part of amino acids, which are used to make proteins -78% of atmosphere is nitrogen, but it must be fixed (changed) in order to be used by organisms
Nitrogen Fixation -nitrogen-fixing bacteria that live on nodules of roots of some plants and lightning convert the nitrogen gas (N2 ) of the air into ammonia (NH3 )	Nitrification -Other bacteria change the ammonia into nitrates (NO3) and nitrites (NO2) -Plants can then use the nitrates and nitrites to make proteins	Ammonia is a result of nitrogen fixation and a component of consumer waste Animals eat the plants (along with the nitrogen in the plants) to make proteins in animals.
Nitrogen in the Environment
Eutrophication -Fertilizers add nitrogen to the soil but it may build up in the lakes and streams -This causes algae to grow very quickly and cover the surface of the water (algae bloom) -This blocks sunlight from reaching plants in the water, which kills the plants -Animals eating the plants then die, sink to the bottom, and decompose -This uses up the oxygen in the water killing more fish	Waste products -Waste products produced by organisms contain ammonia, nitrates, and nitrites	Decomposers When organisms die, decomposers break them down and release nitrogen back into the soil -Denitrification - Some bacteria breakdown the nitrates back into nitrogen gas when enters the atmosphere again