1. Bacteria convert N (gas) ---> Ammonia via nitrogen fixation 2. Ammonia --> Nitrates to be used by plants 3. Animals can obtain nitrogen by eating plants 4. Excess nitrates in soil --> N (gas) by bacteria (denitrification) The movement of nitrogen through ecosystems, the soil and the atmosphere

Nitrate (NO3) ---> Nitrogen (N2) back into the atmosphere

A2 (Half assed) Flashcards by Dev P

Biogeochemical Cycles

Complex cyclical transfer of nutriets from the environment to organisms and back to the environment

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Hydrological Cycle

The circular movement of water from the ocean reservoir to the air (cloud), back to the Earth in the form of rain, snow, and finally back to the ocean reservoir via streams and estuaries

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Evaporation

Liquid to vapor

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Condensation

Water vapor to liquid

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Transpiration

Water vapor loss in plant (cooling when hot)

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Precipitation

Rain / Snow / Sleet / Hail falls to the ground

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Runoff

More water than land can absorb runs into creek / streams / ponds

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Percolation

Rain water seeps into soil and filters down

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What “powers” the water cycle

Solar energy and gravity

Solar energy causes water to evaporate from the soil, plants, ocean, lakes, streams
Warm air rises and lifts the water into the atmosphere, where it forms clouds
Gravity pulls it down again as rain and snow

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Oxygen Cycle

The oxygen cycle is closely related to the carbon cycle as they are linked by both photosyntehsis and cellular respiration

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Evidence of an oxygen rich atmosphere

Stromatolites

Dome-shaped rocks composed of thin layers of sediment pressed tightly together.

Formed by photosynthetic cyanobacteria

Cross sections show red-iron bands help reveal what the composition of the ancient atmosphere was like

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Evidence of an oxygen rich atmosphere

Banded Iron Formations

Thought to have as oxygen produced by cyanobacteria reacted with dissolved iron in the oceans and precipitated out, forming a thin layer on the ocean floor

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Nitrogen Cycle

Bacteria convert N (gas) —> Ammonia via nitrogen fixation
Ammonia –> Nitrates to be used by plants
Animals can obtain nitrogen by eating plants
Excess nitrates in soil –> N (gas) by bacteria (denitrification)

The movement of nitrogen through ecosystems, the soil and the atmosphere

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Nitrogen Fixation

Nitrogen –> Ammonium

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Nitrification

Ammonium –> Nitrites by bacteria

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Assimilation

PLants absorb nitrates into roots

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Consumption

Organisms eat plants

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Ammonification

Organisms excrete wastes/dies

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Denitrification

Nitrate (NO₃) —> Nitrogen (N₂) back into the atmosphere

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N-fixing bacteria

Convert nitrogen to ammonium for plants and plants provide bacteria with sugars produced via photosynthesis

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Phosphorus

Key element in ceell membranes, energy releasing molecules, DNA and in calcium phosphate of bones

Phosphorus Cycle

Water gradually releases phosphorus in trapped rocks
PLants can only use in the form of phosphates (dissolved in water)
Can be absorbed by phtoosynthesis organisms and enter into food chains
Can be eroded from rock and carried by water from land to rivers and then to oceans; absorbed by algae (then food chains)
Organic waste recycled by decomposeres who release phosphates

Carbon

The key element o fall organisms from bacteria to humans

- It forms the backbone of many molecules from DNA to proteins to sugars

Where do autotrophs absorb carbon from?

The atmosphere

Carbohydrates
Lipids
Carbon containing compounds

Convert it to:

Autotrophs ____ the carbon dioxide concentration in the atmosphere

Decrease

True or False: Carbon Dioxide is water soluble | IB

- It can remain as a dissolved gas in water - It can combine with water to form carbonic acid (H₂CO₃)

Carbonic acid can dissociate to form ____ and _____ ____ | IB

Hydrogen and Hydrogen Carbonate | This lowers the pH of the water

Who uses carbonic acid and carbon dioxide | IB

Aquatic plants and autotrophs

Autotrophs use carbon dioxide to produce ____ compounds by photosynthesis (or chemosysntehsis) | IB

Carbon | Reduces concentration of CO₂ inside autotrophs ## Footnote Carbon Dioxide diffuses into Autotrophs

Carbon moves between organisms and the atmisohere as a result of both ____ and ____ ____ | IB

Photosynthesis, cellular respiration

Photosynthesis removes ____ from the atmosphere | IB

Carbon Dioxide (CO₂)

Cellular respiration by primary consumers and consumers, including decomposers returns ____ to the atmosphere | IB

Carbon in the form of Carbon Dioxide (CO₂)

Any cell that uses aerobic cellular respiration produces ___ ____ | IB

Carbon Dioxide ## Footnote - Non-Photosynthetic Cells (roots in plants) - Animal Cells - Saprotrophs such as fungi

Methanogensis | IB

Carbon dioxide is a product of aerobic respiration; Methane is the result of anaerobic respiration

Oxidiation of Methane (Formula)

CH₄ + 2 O₂ ➡ 2 H₂O + CO₂ | Naturally oxidzed in the stratosphere

Saprotrophs typically digest dead ____ and other _____ _____ | IB

Leaves, Organic Matter

Saprotrophs obtain oxygen from | IB

Air spaces in soil

Peat

Dark brown acidic material that covoers 3% of land surface ## Footnote - Some environments are waterlogged and therefore use anaerobic respiration ➡ Causes acidic conditions to develop - Saprotrophs cannot survive in acidic conditions or without oxygen readily availible so matter is not fully decomposed

Peat becomes ____ (How)

Coal | Peat is under sediment layers; heat and pressure remove moisturue

Oil and natural form in ____ below seas and lakes | IB

Mud

Organisms have hard body parts made of ____ ____ | IB

Calcium Carbonate | - Mollusc Shells - Hard corals nuild reefs by secreting CaCO₃

Limestone is a result of ____ ____ that is deposited by precipitation in the water

Calcium carbonate

Two most significant gasses | IB

Carbon Dioxide: - Released by cellular respiration and combustion of biomass and fossil fuels - Removed via photosynthesis Water Vapor: - Formed by evaporation from oceans and transpiration in plants - Removed by rainfall/snow or other forms of precipitation

Less impactful greenhouse gases | IB

Methane: - Third most significant - Emitted from marshes, waterlogged habitats, landfills with organic wastes; released during extraction of fossil fuels and melting ice Nitrous Oxide: - Released naturally by bacteria, also released by agriculture and vehicle exhausts

A greenhouse gas effect depends on | IB

- Ability to absorb long-wave radiation (the more it absorbs, the larger the effect) - Concentration in the atmosphere (rate that it is released + how long it remains there)

Earth absorbs ____-____ energy and then remits it at ____ ____ | IB

Short-wave, longer wavelenghts

____-____ radiation is re-emitted towards Earth which ____ the Earth | IB

Longer-wave, warms

**True** or **False**: Greenhouse gases can absorb energy at all wavelenghts | IB

**False**: Greenhouse gases can only absorb energy in specific wavelenghts

Impact of chaning concentration of greenhouse gases | IB

Dynamic equillibrium is changed and thus the size of its contribution | This could cause global temperatures to rise or fall

Milankovitch Cycles | IB

Periodic changes in the orbital characteristics of a planet that control how much sunlight it recieves | Eccentricity (Kepler's First Law - Physics 20)

Factors contributing to Earth warming (except GHG's) | IB

1. Milankovich cycles in the Earth's orbit 2. Variation in sunspot activity ## Footnote However, it can also change factors other than climate: - Increased temp = increased evaporation - Increased extreme weather conditions (tropical storms) - Changes to circulating ocean currents

At night if the sky is clear, temperatues will ____ quicker than if cloud cover was present | IB

Fall | This is because of water vapor