My AP Biology Thoughts  

Unit 1 Episode #36

Segment 1: Introduction To The Carbon Cycle

Carbon cycle Def 

• The way nature reuses carbon atoms
• The process in which carbon travels from the atmosphere into organisms and the Earth and back into the atmosphere

Background info about cycle

Carbon in constant state of movement from place to place and stored in reservoirs - moves between these reservoirs through photosynthesis, burning fossil fuels, respiration, etc.

• Cycle = cyclic - if you start at one reservoir, you will get back to that same reservoir
• Earth = closed system - amount of carbon on the planet never changes
• Nature keeps carbon levels balanced - amount of carbon released from reservoirs equal to amount obtained by same reservoirs

Steps

• Carbon moves from atmosphere to plants - carbon first came from frequent volcanic activity and asteroid impacts - carbon attached to oxygen in CO2
• For photosynthesis, CO2 is pulled from the air by plants to help in the process of producing food in the form of glucose which the plants consumes
• Carbon moves from plants to animals through food chains - animals eat these plants that have this carbon that the plants got from atmosphere
• Carbon moves plants and animals to soil - bodies, wood, leaves decay - carbon released as production from decomposition reaction go into ground - buried sometimes and turned in fossil fuels in millions of years
• Fossil fuels burned as human energy resources, carbon is then moved to the atmosphere as carbon dioxide - every year, 5.5 billion tons of carbon is released by burning fossil fuels and around 60% of this amount stays in the atmosphere while remainder becomes dissolved in seawater
• Carbon can get to atmosphere by respiration - release carbon dioxide as animals exhale - producers use energy from sunlight to make bonds between carbon atoms; animals break these bonds to release the energy they contain - turns carbon compounds into single carbon units - released into atmosphere as carbon dioxide
• Carbon could be released back into the atmosphere - volcanoes erupt, fires blaze, solid waste
• Carbon moves from the atmosphere to bodies of water - bodies of water absorb carbon from the atmosphere - dissolved into water
• Oceans release CO2 - carbon dioxide from atmosphere comes into contact with ocean water - reacts with water molecules to form carbonic acid
• When carbonic acid > carbon dioxide amount in the atmosphere, some carbonic acid may be released into the atmosphere as carbon dioxide

Segment 2: Getting Into Specifics: The Carbon Cycle

• Geosphere
• Geological component of the carbon cycle - operates slowly 
• Important determinant of amount of carbon in the atmosphere 
• Of the carbon stored in geosphere, 80% of it is limestone and its derivatives which form from the sedimentation of calcium carbonate stored in the shells of marine organisms; other 20% is stored as kerogen (organic matter in sedimentary rocks) - kerogen formed through the sedimentation and burial of terrestrial organisms under high heat and pressure
• How its released into atmosphere
• Carbon dioxide could be released during the metamorphism of carbonate rock - recycled into the Earth’s mantle at convergent boundaries.
• Through volcanoes and hotspots
• Removed by humans through extraction of kerogens in form of fossil fuels - burned and emit carbon
• Ocean reservoir - biological pump
• Ocean divided into surface layer and mixed layer 300 feet below
• Dissolved inorganic carbon in the surface layer exchanged rapidly with the atmosphere - deep ocean contains more carbon mainly due to its larger volume - exchange of carbon between these two layers of the ocean is extremely slow
• Carbon enters the ocean through the dissolution of atmospheric carbon dioxide - small part of turned into carbonate; can also enter through rivers as dissolved organic carbon
• It is converted by organisms into organic carbon through photosynthesis and can then be either exchanged throughout the aquatic food chain or end up in the deeper carbon rich layers of the ocean as dead soft tissue or in shells as calcium carbonate
• The carbon can stay in deep layer for a while before being deposited as sediment or returned to the surface of the water
• When the aquatic organisms that contain carbon die and decompose, they also release carbon dioxide back into the water
• Terrestrial biosphere
• Most carbon is organic - ⅓ stored in inorganic forms like calcium carbonate
• Carbon uptake in the terrestrial biosphere is dependent on biotic factors - follows a diurnal and seasonal cycle
• Carbon can leave reservoir by being exported into the ocean or rivers by erosion or into the atmosphere through soil respiration (carbon in soil being respires by soil organisms)
• Fast carbon cycle
• Present in biosphere - complete within years
• Moves carbon from atmosphere to biosphere to atmosphere
• Involves short-term biogeochemical processes between the environment and living organisms in the biosphere
• Consists of the movement of carbon between the atmosphere and terrestrial and marine ecosystems, and soils and seafloor sediments
• Involves the annual and seasonal processes of photosynthesis, vegetative growth and decomposition
• Slow carbon cycle
• Can take millions of years to complete
• Moves carbon through the Earth’s crust between rocks, soil, the ocean, and the atmosphere
• Includes longer geochemical processes that involve the rock cycle - weathering of rocks can take millions of years
• Exchange that takes place between the ocean and atmosphere can take centuries 
• Mountain building is what returns this geological carbon to Earth’s surface - takes hundreds of thousands of years
• Deep carbon cycle
• The movement of carbon through the Earth’s mantle and core
• Deep carbon cycle enables carbon to return to Earth - maintains living organisms of Earth

Segment 3: Digging Deeper Into the Carbon Cycle

• Carbon - building block for life and is known as such due to its ability to form complex macromolecules
• The backbones or components for macromolecules is carbon - the carbon atom has properties that enable it to form covalent bonds to as many as 4 different atoms, making this element versatile and ideal to serve as the basic structural component of macromolecules
• Proteins
• Made up of an amino group (has C), a carboxylic group (has C), and a side chain (made up of C) - all connected by and bonded to a carbon atom
• Function - allow metabolic reactions to take place, they provide a source of energy, they assist in cellular and tissue repairs, they form blood cells, they catalyze reactions, etc.
• Lipids
• Made up on hydrocarbon fatty acid tails
• Function: allow for energy storage, insulation, cellular communication and protection
• Carbs
•  Made primarily of a carbon chain and an aldehyde and a ketone, which both also consist of carbons
• Function: enable humans to attain their energy and fuel that they need to function physically and mentally
• Nucleic acids
• Consist of carbon in the sugar phosphates that make them up
• Function: hold the instructions needed for an organism to develop, survive, and reproduce; protein synthesis
• Carbon/CO2 important aspects
• Allow photosynthesis to be possible - assures that all heterotrophs and autotrophs don’t die
• Major part of cellular respiration
• Carbon dioxide and greenhouse gases in general keep our planet livable by holding onto some of Earth’s heat energy so that it doesn’t all escape into space - enables heat to be retained in the atmosphere 
• Human impacts on carbon cycle
• Carbon cycle normally works to ensure the stability of variables such as the Earth’s atmosphere, the acidity of the ocean, and the availability of carbon for use by living things
• Humans, by burning fossil fuels, deforestation, geological and carbon sequestration, and by using limestone to make concrete have caused a drastic increase in the rise of carbon dioxide in the atmosphere
• More and more carbon in the air = more heat energy being absorbed and global temperatures rising and rising and weather is changing all over and becoming more extreme
• Ocean acidification - reducing the amount of carbonate that coral and plankton need and killing off aquatic life not suited for lower pH’s
• No true stability; balance of cycle and amounts of carbon in different reservoirs messed up
• Great amount of carbon in atmosphere (affects ecological aspects) → this carbon dioxide taken in by plants, the ocean, and aquatic organisms → ocean acidification; plants attaining too much CO2 - thicken their leaves and photosynthesis less → heterotrophs could eat plants with excessive amounts of carbon or inhale it from atmosphere → too much carbon dioxide can kill animals since it can decrease the amount of oxygen reaching the body

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

• “Ice Flow” Kevin MacLeod (incompetech.com)
• Licensed under Creative Commons: By Attribution 4.0 License
• http://creativecommons.org/licenses/by/4.0/

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