Biogeochemical Cycles

1. Watch these Videos

1.a. Biogeochemical Cycles

1a. Carbon Cycle Song

2. Study this Summary: Biogeochemical Cycles — Key Concepts

Overview

A biogeochemical cycle tracks the movement of elements or compounds between the biotic (living) and abiotic (non-living) parts of an ecosystem
Key components: reservoirs (where elements accumulate) and fluxes (processes that move elements between reservoirs)

Carbon Cycle

Carbon is the backbone of all major biological molecules: carbohydrates, lipids, proteins, and nucleic acids
Into the biosphere: CO₂ is fixed from the atmosphere into organic compounds during photosynthesis (Calvin cycle)
Back to atmosphere: returned via cellular respiration (plants and animals), decomposition by fungi and bacteria, and fossil fuel combustion
Fossil fuels form when ancient plant matter is compressed faster than it can decompose; burning them releases CO₂ at a rate that disrupts the climate system

Nitrogen Cycle

Nitrogen makes up 78% of the atmosphere, but atmospheric N₂ is held by a triple bond and cannot be used directly by most organisms
Biologically essential: found in amino acids (proteins), nitrogenous bases (DNA/RNA), and chitin (insect exoskeletons)
Soil bacteria are the key drivers of the nitrogen cycle — they carry out all four of its major processes:
- Nitrogen fixation converts N₂ → ammonia (NH₃) — carried out by symbiotic bacteria in legume root nodules and free-living soil bacteria/archaea; plants cannot do this themselves
- Nitrification converts ammonia → nitrites → nitrates, carried out by nitrifying bacteria
- Assimilation is the uptake of nitrates and nitrites by non-legume plant roots
- Ammonification by decomposers breaks down organic nitrogen (from dead organisms) back into ammonia compounds
- Denitrification by specialized bacteria uses nitrates in anaerobic respiration, converting them back to N₂ gas — this removes nitrogen from the cycle and returns it to the atmosphere

Water Cycle

The hydrosphere is all water on, under, and above Earth’s surface — oceans, rivers, lakes, groundwater, glaciers, and water vapor
Unlike carbon and nitrogen, water doesn’t change its chemical form — it’s always H₂O, but changes state (liquid, solid, gas)
Water reservoirs ranked from largest to smallest: oceans → surface water (lakes/rivers) → atmosphere → living organisms
Key fluxes:
- Evaporation — liquid water becomes water vapor, mainly from oceans and other surface water
- Transpiration — water moves through plants and exits as vapor through leaves; reduced transpiration (e.g., during drought) means less water vapor enters the atmosphere
- Condensation — water vapor cools and forms clouds (which are liquid water droplets, not gas)
- Precipitation — water falls as rain, snow, or hail when droplets become too heavy to stay suspended
- Runoff — water flows over land into streams, rivers, lakes, and oceans; this also transports phosphate, linking the water cycle to the phosphorus cycle
- Groundwater flow — water infiltrates soil and percolates into underground reservoirs, eventually returning to oceans

Phosphorus Cycle

Phosphorus cycles as the phosphate ion (PO₄³⁻) and is critical for ATP, DNA/RNA backbones, phospholipids, and bone (hydroxyapatite)
Unlike carbon and nitrogen, phosphorus has no gaseous phase — it does not cycle through the atmosphere; the cycle runs through soil, water, and organisms
Weathering releases phosphate from rocks into the soil — this is how new phosphate enters the cycle; after weathering, phosphate is first taken up by producers (plants)
Terrestrial cycle: weathering → assimilation by plants → consumption by animals → returned to soil via decomposition and animal waste; phosphate mining is an artificial input
Aquatic cycle: phosphate enters water via natural and agricultural runoff (the water cycle is the transport mechanism here) → absorbed by algae → passed to fish → when organisms die, phosphate sinks in sedimentation, locking it away for tens of millions of years
Decomposition is critical because it returns phosphate from dead organic matter back to the soil and water, where producers can use it again
Phosphate is only returned from sediments through geological uplift, tectonic activity, or volcanic activity
Phosphate is a non-renewable resource — it is being mined and lost to sedimentation far faster than it can be replenished, posing a serious future challenge

3. Flashcards

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4. Multiple Choice Quiz 1: Biogeochemical Cycles

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5. Multiple Choice Quiz 2: More about the Carbon Cycle

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[h]Carbon Cycle

[i]

[q]In an ecosystem, an example of an abiotic factor would be

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[q]In an ecosystem, an example of a biotic factor would be

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[q]Carbon fixation changes

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[q ]Of the processes below, the one that’s most related to carbon fixation is

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[q]Photosynthesis

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[q]Cellular respiration

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[q]Decomposition

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[q]Combustion

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[q]In the diagram below, ecological producers are shown at

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[q]In the diagram below, ecological consumers are shown at

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[q]In the diagram below, decomposers are shown at

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[f]IE5vLiBMZXR0ZXIgQiByZWZlcnMgdG8gcHJvZHVjZXJzLCB0aGUgb3JnYW5pc21zLiB0aGF0IHB1bGwgYWJpb3RpYyBjYXJib24gZGlveGlkZSBvdXQgb2YgdGhlIGFpciBhbmQgdXNlIGl0IHRvIHByb2R1Y2UgZm9vZCAoY2FyYm9oeWRyYXRlcykuIEZpbmQgYSBsZXR0ZXIgdGhhdCByZWZlcnMgdG8gYSBncm91cCBvZiBvcmdhbmlzbXMgdGhhdCB0YWtlIGRlYWQgcGxhbnRzIGFuZCBhbmltYWxzIGFuZCBicmVha3MgdGhlbSBkb3duLCByZWxlYXNpbmcgY2FyYm9uIGRpb3hpZGUu[Qq]

[f]IE5vLiBMZXR0ZXIgQyByZWZlcnMgdG8gZWNvbG9naWNhbCBjb25zdW1lcnM6IGFuaW1hbHMgdGhhdCBlYXQgcHJvZHVjZXJzLiBGaW5kIGEgbGV0dGVyIHRoYXQgcmVmZXJzIHRvIGEgZ3JvdXAgb2Ygb3JnYW5pc21zIHRoYXQgdGFrZSBkZWFkIHBsYW50cyBhbmQgYW5pbWFscyBhbmQgYnJlYWtzIHRoZW0gZG93biwgcmVsZWFzaW5nIGNhcmJvbiBkaW94aWRlLg==[Qq]

[f]IFllcy4gTGV0dGVyIEQgcmVmZXJzIHRvIGRlY29tcG9zZXJzLCB3aGljaCBhcmUgb3JnYW5pc21zIHRoYXQgdGFrZSBkZWFkIHBsYW50cyBhbmQgYW5pbWFscyBhbmQgYnJlYWsgdGhlbSBkb3duIGludG8gc2ltcGxlciBmb3JtcywgaW5jbHVkaW5nIGNhcmJvbiBkaW94aWRlLg==[Qq]

[f]IE5vLiBMZXR0ZXIgRSByZWZlcnMgdG8gZm9zc2lsIGZ1ZWxzLiBGaW5kIGEgbGV0dGVyIHRoYXQgcmVmZXJzIHRvIGEgZ3JvdXAgb2Ygb3JnYW5pc21zIHRoYXQgdGFrZSBkZWFkIHBsYW50cyBhbmQgYW5pbWFscyBhbmQgYnJlYWtzIHRoZW0gZG93biwgcmVsZWFzaW5nIGNhcmJvbiBkaW94aWRlLg==[Qq]

[q]In the diagram below, carbon dioxide gas is shown at

[c]IEEgwqAg wqDCoA==[Qq][c]IEIgwqAgwqDCoA==[Qq][c]IEMgwqAgwqDCoA==[Qq][c]IEQgwqAgwqDCoA==[Qq][c]IEU=

Cg==[Qq]

[f]IFllcy4gTGV0dGVyIEEgcmVmZXJzIHRvIGNhcmJvbiBkaW94aWRlIGluIHRoZSBhaXIu[Qq]

[f]IE5vLiBMZXR0ZXIgQyByZWZlcnMgdG8gZWNvbG9naWNhbCBjb25zdW1lcnM6IGFuaW1hbHMgdGhhdCBlYXQgcHJvZHVjZXJzLiBGaW5kIGEgbGV0dGVyIHRoYXQgcmVmZXJzIHRvIGNhcmJvbiBkaW94aWRlIG1vbGVjdWxlcyBpbiB0aGUgYWlyLg==[Qq]

[f]IE5vLiBMZXR0ZXIgRCByZWZlcnMgdG8gZGVjb21wb3NlcnMsIGEgZ3JvdXAgb2Ygb3JnYW5pc21zIHRoYXQgdGFrZSBkZWFkIHBsYW50cyBhbmQgYW5pbWFscyBhbmQgYnJlYWtzIHRoZW0gZG93biwgcmVsZWFzaW5nIGNhcmJvbiBkaW94aWRlLiBGaW5kIGEgbGV0dGVyIHRoYXQgcmVmZXJzIHRvIGNhcmJvbiBkaW94aWRlIG1vbGVjdWxlcyBpbiB0aGUgYWlyLg==[Qq]

[f]IE5vLiBMZXR0ZXIgRSByZWZlcnMgdG8gZm9zc2lsIGZ1ZWxzLiBGaW5kIGEgbGV0dGVyIHRoYXQgcmVmZXJzIHRvIGNhcmJvbiBkaW94aWRlIG1vbGVjdWxlcyBpbiB0aGUgYWlyLg==[Qq]

[q]In the diagram below, fossil fuels are shown at

[c]IEEgwqAgwqDCoA==[Qq][c]IEIgwqAgwqDCoA==[Qq][c]IEMgwqAgwqDCoA==[Qq][c]IEQgwqAgwqDCoA==[Qq][c]IE U=

Cg==[Qq]

[f]IE5vLiBMZXR0ZXIgQSByZWZlcnMgdG8gY2FyYm9uIGRpb3hpZGUgaW4gdGhlIGFpci4gRmluZCBhIGxldHRlciB0aGF0IHNob3dzIGNhcmJvbiB0aGF04oCZcyBiZWVuIHRyYW5zZm9ybWVkIGludG8gb2lsIChwZXRyb2xldW0pLCBjb2FsLCBvciBuYXR1cmFsIGdhcy4=[Qq]

[f]IE5vLiBMZXR0ZXIgQiByZWZlcnMgdG8gcHJvZHVjZXJzLCB0aGUgb3JnYW5pc21zIHRoYXQgcHVsbCBhYmlvdGljIGNhcmJvbiBkaW94aWRlIG91dCBvZiB0aGUgYWlyLCBhbmQgdXNlIGl0IHRvIHByb2R1Y2UgZm9vZCAoY2FyYm9oeWRyYXRlKS4gRmluZCBhIGxldHRlciB0aGF0IHNob3dzIGNhcmJvbiB0aGF04oCZcyBiZWVuIHRyYW5zZm9ybWVkIGludG8gb2lsIChwZXRyb2xldW0pLCBjb2FsLCBvciBuYXR1cmFsIGdhcy4=[Qq]

[f]IE5vLiBMZXR0ZXIgQyByZWZlcnMgdG8gZWNvbG9naWNhbCBjb25zdW1lcnM6IGFuaW1hbHMgdGhhdCBlYXQgcHJvZHVjZXJzLiBGaW5kIGEgbGV0dGVyIHRoYXQgc2hvd3MgY2FyYm9uIHRoYXTigJlzIGJlZW4gdHJhbnNmb3JtZWQgaW50byBvaWwgKHBldHJvbGV1bSksIGNvYWwsIG9yIG5hdHVyYWwgZ2FzLg==[Qq]

[f]IE5vLiBMZXR0ZXIgRCByZWZlcnMgdG8gZGVjb21wb3NlcnMsIGEgZ3JvdXAgb2Ygb3JnYW5pc21zIHRoYXQgdGFrZSBkZWFkIHBsYW50cyBhbmQgYW5pbWFscyBhbmQgYnJlYWtzIHRoZW0gZG93biwgcmVsZWFzaW5nIGNhcmJvbiBkaW94aWRlLiBGaW5kIGEgbGV0dGVyIHRoYXQgc2hvd3MgY2FyYm9uIHRoYXTigJlzIGJlZW4gdHJhbnNmb3JtZWQgaW50byBvaWwgKHBldHJvbGV1bSksIGNvYWwsIG9yIG5hdHVyYWwgZ2FzLg==[Qq]

[f]IFllcy4gTGV0dGVyIEUgcmVmZXJzIHRvIGZvc3NpbCBmdWVscy4gRm9zc2lsIGZ1ZWxzIGNvbnNpc3Qgb2YgY29hbCwgb2lsIChwZXRyb2xldW0pLCBvciBuYXR1cmFsIGdhcy4=[Qq]

[q]In the diagram below, the only process that removes carbon dioxide from the atmosphere is

[c]IDEgwqAg wqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAgwqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]IDU=

Cg==[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDEgcmVmZXJzIHRvIHBob3Rvc3ludGhlc2lzLCB0aGUgb25seSBwcm9jZXNzIHRoYXQgcmVtb3ZlcyBjYXJib24gZGlveGlkZSBmcm9tIHRoZSBhdG1vc3BoZXJlLg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMiByZWZlcnMgdG8gcmVzcGlyYXRpb24gZnJvbSBwbGFudHMuIExpa2UgYWxsIGNlbGx1bGFyIHJlc3BpcmF0aW9uLCB0aGlzIGFkZHMgY2FyYm9uIGRpb3hpZGUgdG8gdGhlIGF0bW9zcGhlcmUuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGRpb3hpZGUgZ2FzIG1vdmluZyBmcm9tIHRoZSBhaXIgYW5kIGJlaW5nIOKAmGZpeGVk4oCZIGluIGEgcGxhbnQu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMyByZWZlcnMgdG8gdGhlIGNvbnN1bXB0aW9uIG9mIHBsYW50cyBieSBhbmltYWxzLiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBkaW94aWRlIGdhcyBtb3ZpbmcgZnJvbSB0aGUgYWlyIGFuZCBiZWluZyDigJhmaXhlZOKAmSBpbiBhIHBsYW50Lg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNCBzaG93cyByZXNwaXJhdGlvbiBmcm9tIGFuaW1hbHMuIExpa2UgYWxsIGNlbGx1bGFyIHJlc3BpcmF0aW9uLCB0aGlzIGFkZHMgY2FyYm9uIGRpb3hpZGUgdG8gdGhlIGF0bW9zcGhlcmUuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGRpb3hpZGUgZ2FzIG1vdmluZyBmcm9tIHRoZSBhaXIgYW5kIGJlaW5nIOKAmGZpeGVk4oCZIGluIGEgcGxhbnQu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gdGhlIGRlYXRoIG9mIGFuaW1hbHMuIFRoZSBtYXR0ZXIgaW4gdGhlc2UgZGVhZCBhbmltYWxzIHdpbGwgYmUgYnJva2VuIGRvd24gYnkgZGVjb21wb3NlcnMuIERlY29tcG9zaXRpb24gYWRkcyBjYXJib24gZGlveGlkZSB0byB0aGUgYXRtb3NwaGVyZS4gTG9vayBmb3IgYW4gYXJyb3cgdGhhdCBzaG93cyBjYXJib24gZGlveGlkZSBnYXMgbW92aW5nIGZyb20gdGhlIGFpciBhbmQgYmVpbmcg4oCYZml4ZWTigJkgaW4gYSBwbGFudC4=[Qq]

[q]In the diagram below, consumption is shown at

[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDMgwqAg wqDCoA==[Qq][c]IDQgwqAgwqDCoA==[Qq][c]IDU=

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMSByZWZlcnMgdG8gcGhvdG9zeW50aGVzaXMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgcGxhbnRzIGJlaW5nIGNvbnN1bWVkIGJ5IGFuaW1hbHMu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMiByZWZlcnMgdG8gcmVzcGlyYXRpb24gZnJvbSBwbGFudHMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgcGxhbnRzIGJlaW5nIGNvbnN1bWVkIGJ5IGFuaW1hbHMu[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDMgcmVmZXJzIHRvIHRoZSBjb25zdW1wdGlvbiBvZiBwbGFudHMgYnkgYW5pbWFscy4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNCBzaG93cyByZXNwaXJhdGlvbiBmcm9tIGFuaW1hbHMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgcGxhbnRzIGJlaW5nIGNvbnN1bWVkIGJ5IGFuaW1hbHMu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gdGhlIGRlYXRoIG9mIGFuaW1hbHMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgcGxhbnRzIGJlaW5nIGNvbnN1bWVkIGJ5IGFuaW1hbHMu[Qq]

[q]In the diagram below, the release of carbon dioxide by decomposition is shown at

[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAgwqDCoA==[Qq][c]IDcgwqAgwqDCoA==[Qq][c]IDggwqAg wqDCoA==[Qq][c]IDEw

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMSByZWZlcnMgdG8gcGhvdG9zeW50aGVzaXMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgdGhlIGRlYWQgcmVtYWlucyBvZiBwbGFudHMgYW5kIGFuaW1hbHMgYmVpbmcgY29udmVydGVkIGludG8gY2FyYm9uIGRpb3hpZGUu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMiByZWZlcnMgdG8gcmVzcGlyYXRpb24gZnJvbSBwbGFudHMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgdGhlIGRlYWQgcmVtYWlucyBvZiBwbGFudHMgYW5kIGFuaW1hbHMgYmVpbmcgY29udmVydGVkIGludG8gY2FyYm9uIGRpb3hpZGUu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNyByZWZlcnMgdG8gZm9zc2lsIGZ1ZWwgZm9ybWF0aW9uLiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIHRoZSBkZWFkIHJlbWFpbnMgb2YgcGxhbnRzIGFuZCBhbmltYWxzIGJlaW5nIGNvbnZlcnRlZCBpbnRvIGNhcmJvbiBkaW94aWRlLg==[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDggc2hvd3MgdGhlIHJlbGVhc2Ugb2YgY2FyYm9uIGRpb3hpZGUgdGhyb3VnaCBkZWNvbXBvc2l0aW9uLCBkdXJpbmcgd2hpY2ggdGhlIGRlYWQgcmVtYWlucyBvZiBwbGFudHMgYW5kIGFuaW1hbHMgYXJlIGNvbnZlcnRlZCBpbnRvIGNhcmJvbiBkaW94aWRlIChhbmQgb3RoZXIgc2ltcGxlIHN1YnN0YW5jZXMpIHRoYXQgY2FuIHJlLWVudGVyIHRoZSBjYXJib24gY3ljbGUgKG9yIG90aGVyIGJpb2dlb2NoZW1pY2FsIGN5Y2xlcyku[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMTAgcmVmZXJzIHRvIHRoZSBjb21idXN0aW9uIG9mIGZvc3NpbCBmdWVscy4gTG9vayBmb3IgYW4gYXJyb3cgdGhhdCBzaG93cyB0aGUgZGVhZCByZW1haW5zIG9mIHBsYW50cyBhbmQgYW5pbWFscyBiZWluZyBjb252ZXJ0ZWQgaW50byBjYXJib24gZGlveGlkZS4=[Qq]

[q]In the diagram below, respiration from plants is shown at

[c]IDEgwqAgwqDCoA==[Qq][c]IDIgwqAg wqDCoA==[Qq][c]IDcgwqAgwqDCoA==[Qq][c]IDggwqAgwqDCoA==[Qq][c]IDEw

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMSByZWZlcnMgdG8gcGhvdG9zeW50aGVzaXMuIExvb2sgZm9yIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGRpb3hpZGUgYmVpbmcgcmVsZWFzZWQgZnJvbSBwbGFudHMgYW5kIGhlYWRpbmcgYmFjayBpbnRvIHRoZSBhdG1vc3BoZXJlLg==[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDIgcmVmZXJzIHRvIHJlc3BpcmF0aW9uIGZyb20gcGxhbnRzLg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNyByZWZlcnMgdG8gZm9zc2lsIGZ1ZWwgZm9ybWF0aW9uLiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBkaW94aWRlIGJlaW5nIHJlbGVhc2VkIGZyb20gcGxhbnRzIGFuZCBoZWFkaW5nIGJhY2sgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgOCBzaG93cyBkZWNvbXBvc2l0aW9uLiBMb29rIGZvciBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBkaW94aWRlIGJlaW5nIHJlbGVhc2VkIGZyb20gcGxhbnRzIGFuZCBoZWFkaW5nIGJhY2sgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMTAgcmVmZXJzIHRvIHRoZSBjb21idXN0aW9uIG9mIGZvc3NpbCBmdWVscy4gTG9vayBmb3IgYW4gYXJyb3cgdGhhdCBzaG93cyBjYXJib24gZGlveGlkZSBiZWluZyByZWxlYXNlZCBmcm9tIHBsYW50cyBhbmQgaGVhZGluZyBiYWNrIGludG8gdGhlIGF0bW9zcGhlcmUu[Qq]

[q]In the diagram below, respiration from animals is shown at

[c]IDQgwqAg wqDCoA==[Qq][c]IDUgwqAgwqDCoA==[Qq][c]IDcgwqAgwqDCoA==[Qq][c]IDggwqAgwqDCoA==[Qq][c]IDEw

Cg==[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDQgcmVmZXJzIHRvIHJlc3BpcmF0aW9uIGZyb20gYW5pbWFscy4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gbWF0dGVyIGZyb20gZGVhZCBhbmltYWxzIG1vdmluZyB0byBkZWNvbXBvc2Vycy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBkaW94aWRlIGJlaW5nIHJlbGVhc2VkIGZyb20gYW5pbWFscyBhbmQgaGVhZGluZyBiYWNrIGludG8gdGhlIGF0bW9zcGhlcmUu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNyByZWZlcnMgdG8gZm9zc2lsIGZ1ZWwgZm9ybWF0aW9uLiBGaW5kIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGRpb3hpZGUgYmVpbmcgcmVsZWFzZWQgZnJvbSBhbmltYWxzIGFuZCBoZWFkaW5nIGJhY2sgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgOCBzaG93cyBkZWNvbXBvc2l0aW9uLiBGaW5kIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGRpb3hpZGUgYmVpbmcgcmVsZWFzZWQgZnJvbSBhbmltYWxzIGFuZCBoZWFkaW5nIGJhY2sgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMTAgcmVmZXJzIHRvIHRoZSBjb21idXN0aW9uIG9mIGZvc3NpbCBmdWVscy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBkaW94aWRlIGJlaW5nIHJlbGVhc2VkIGZyb20gYW5pbWFscyBhbmQgaGVhZGluZyBiYWNrIGludG8gdGhlIGF0bW9zcGhlcmUu[Qq]

[q]In the diagram below, the formation of fossil fuels is shown at

[c]IDQgwqAgwqA=[Qq][c]IDUgwqAgwqDCoA==[Qq][c]IDcgwqAg wqDCoA==[Qq][c]IDggwqAgwqDCoA==[Qq][c]IDEw

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNCByZWZlcnMgdG8gcmVzcGlyYXRpb24gZnJvbSBhbmltYWxzLiBGaW5kIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIG1vdmluZyBmcm9tIHBsYW50cyBpbnRvIGZvc3NpbCBmdWVscyAob2lsL3BldHJvbGV1bSwgY29hbCwgb3IgbmF0dXJhbCBnYXMpLg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gbWF0dGVyIGZyb20gZGVhZCBhbmltYWxzIG1vdmluZyB0byBkZWNvbXBvc2Vycy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBtb3ZpbmcgZnJvbSBwbGFudHMgaW50byBmb3NzaWwgZnVlbHMgKG9pbC9wZXRyb2xldW0sIGNvYWwsIG9yIG5hdHVyYWwgZ2FzKS4=[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDcgcmVmZXJzIHRvIGZvc3NpbCBmdWVsIGZvcm1hdGlvbi4=[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgOCBzaG93cyBjYXJib24gZGlveGlkZSByZWxlYXNlZCBmcm9tIGRlY29tcG9zaXRpb24uIEZpbmQgYW4gYXJyb3cgdGhhdCBzaG93cyBjYXJib24gbW92aW5nIGZyb20gcGxhbnRzIGludG8gZm9zc2lsIGZ1ZWxzIChvaWwvcGV0cm9sZXVtLCBjb2FsLCBvciBuYXR1cmFsIGdhcyku[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgMTAgcmVmZXJzIHRvIHRoZSBjb21idXN0aW9uIG9mIGZvc3NpbCBmdWVscy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBtb3ZpbmcgZnJvbSBwbGFudHMgaW50byBmb3NzaWwgZnVlbHMgKG9pbC9wZXRyb2xldW0sIGNvYWwsIG9yIG5hdHVyYWwgZ2FzKS4=[Qq]

[q]In the diagram below, the combustion of fossil fuels is shown at

[c]IDQgwqAgwqA=[Qq][c]IDUgwqAgwqA=[Qq][c]IDcgwqAgwqA=[Qq][c]IDggwqAgwqDCoA==[Qq][c]ID Ew

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNCByZWZlcnMgdG8gcmVzcGlyYXRpb24gZnJvbSBhbmltYWxzLiBGaW5kIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGZyb20gZm9zc2lsIGZ1ZWxzIG1vdmluZyBmcm9tIG1hY2hpbmVzIG9yIGZhY3RvcmllcyBpbnRvIHRoZSBhdG1vc3BoZXJlLg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gbWF0dGVyIGZyb20gZGVhZCBhbmltYWxzIG1vdmluZyB0byBkZWNvbXBvc2Vycy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBmcm9tIGZvc3NpbCBmdWVscyBtb3ZpbmcgZnJvbSBtYWNoaW5lcyBvciBmYWN0b3JpZXMgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLCBidXQgeW914oCZcmUgY2xvc2UuIEFycm93IG51bWJlciA3IHJlZmVycyB0byBmb3NzaWwgZnVlbCBmb3JtYXRpb24uIEZpbmQgYW4gYXJyb3cgdGhhdCBzaG93cyBjYXJib24gZnJvbSBmb3NzaWwgZnVlbHMgbW92aW5nIGZyb20gbWFjaGluZXMgb3IgZmFjdG9yaWVzIGludG8gdGhlIGF0bW9zcGhlcmUu[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgOCBzaG93cyBjYXJib24gZGlveGlkZSByZWxlYXNlZCBmcm9tIGRlY29tcG9zaXRpb24uIEZpbmQgYW4gYXJyb3cgdGhhdCBzaG93cyBjYXJib24gZnJvbSBmb3NzaWwgZnVlbHMgbW92aW5nIGZyb20gbWFjaGluZXMgb3IgZmFjdG9yaWVzIGludG8gdGhlIGF0bW9zcGhlcmUu[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDEwIHJlZmVycyB0byB0aGUgY29tYnVzdGlvbiBvZiBmb3NzaWwgZnVlbHMu[Qq]

[q]In the diagram below, the process that is currently causing our planet’s atmospheric carbon dioxide levels to dramatically rise is shown at

[c]IDQgwqAgwqDCoA==[Qq][c]IDUgwqAgwqDCoA==[Qq][c]IDcgwqAgwqDCoA==[Qq][c]IDggwqAgwqDCoA==[Qq][c]ID Ew

Cg==[Qq]

[f]IE5vLiBBcnJvdyBudW1iZXIgNSByZWZlcnMgdG8gbWF0dGVyIGZyb20gZGVhZCBhbmltYWxzIG1vdmluZyB0byBkZWNvbXBvc2Vycy4gRmluZCBhbiBhcnJvdyB0aGF0IHNob3dzIGNhcmJvbiBmcm9tIGZvc3NpbCBmdWVscyBtb3ZpbmcgZnJvbSBtYWNoaW5lcyBvciBmYWN0b3JpZXMgaW50byB0aGUgYXRtb3NwaGVyZS4=[Qq]

[f]IE5vLCBidXQgeW914oCZcmUgb24gdGhlIHJpZ2h0IHRyYWNrLiBBcnJvdyBudW1iZXIgNyByZWZlcnMgdG8gZm9zc2lsIGZ1ZWwgZm9ybWF0aW9uLiBGaW5kIGFuIGFycm93IHRoYXQgc2hvd3MgY2FyYm9uIGZyb20gZm9zc2lsIGZ1ZWxzIG1vdmluZyBmcm9tIG1hY2hpbmVzIG9yIGZhY3RvcmllcyBpbnRvIHRoZSBhdG1vc3BoZXJlLg==[Qq]

[f]IFllcy4gQXJyb3cgbnVtYmVyIDEwIHJlZmVycyB0byB0aGUgY29tYnVzdGlvbiBvZiBmb3NzaWwgZnVlbHMuIFRoZSBzdWRkZW4gcmVsZWFzZSBvZiBjYXJib24gZGlveGlkZSB0aGF0IGhhZCBiZWVuIG91dCBvZiB0aGUgY2FyYm9uIGN5Y2xlIGZvciBtaWxsaW9ucyBvZiB5ZWFycyBoYXMgY2F1c2VkIGNhcmJvbiBkaW94aWRlIGxldmVscyB0byByaXNlIHNpZ25pZmljYW50bHkgZHVyaW5nIHRoZSBwYXN0IHR3byBodW5kcmVkIHllYXJzLg==[Qq]

[x][restart]
[/qwiz]

What’s Next?

Please proceed to this next tutorial: Population Growth