Campbell Biology: Concepts & Connections, Chapter 2- Biochemical cycles

Water Cycle 

Evaporation - liquid to gas

Transpiration - liquid to gas

Condensation - gas to liquid

Precipitation - movement from the atmosphere to the biosphere

Runoff - the movement of precipitation to lakes streams rivers and oceans

Groundwater - water found underground

Carbon Cycle

Carbon is needed to build all organic molecules!

Photosynthesis- Plants remove Carbon dioxide from the atmosphere - store carbon in carbohydrates or starches - pass it to consumers

Respiration- Plants & animals release carbon dioxide back into the air

Decomposition- Decomposers return carbon to the environment when organisms and their waste are processed

Combustion – The burning of Fossil fuels returns Carbon Dioxide to the atmosphere

Deforestation - decreases the amount of carbon dioxide removed from the atmosphere

Nitrogen Cycle 

• Atmospheric nitrogen
• Nitrogen Fixation
• Synthesis of Amino Acids
• Decomposition
• Fertilizers
• Runoff

NITROGEN - needed in proteins and nucleic acids

Nitrogen in atmosphere = N2

Problem? Only one type of organism can take it OUT of the

air and turn it into a usable form for organisms

• BACTERIA!
• perform Nitrogen Fixation (convert N2 to NH3) which picks
• up H+ to become ammonium (NH4+)

Convert ammonium (NH4+) to nitrate (NO3-) for plants

Once nitrogen fixation occurs, nitrogen-containing compounds can then move through an ecosystem.

Plants can absorb & use nitrates (NO3-) to make proteins

Consumers eat plants & get proteins containing nitrogen

Decomposers break down dead organisms & return nitrogen to the soil (NH4+) and (NO3-). Denitrifying bacteria convert (NO3-) back to N2 to be released back into the atmosphere.

Phosphorous Cycle 

Needed by animals to form teeth and bones, parts of molecules like DNA, RNA, and ATP

The slow cycle relies on the uplift and weathering of rock to add inorganic phosphate (PO 4-3) to the soil.

Rarely atmospheric - hardly occurs in a gaseous state

Plants assimilate and build into molecules

Moves to consumers when they eat plants

Decomposition of waste and dead organisms

Fertilizer and Runoff into the water... settle...becomes the new rock that will eventually uplift again

Oxygen Cycle 

Needed for cellular respiration - to make ATP!

Released through Photosynthesis

Lost through Respiration and Decay

Lost through the formation of rust

Oxidation

Gain through weathering

Calcium Carbonate shells🡪Limestone🡪oxygen when organisms disturb ground to get at nutrients.

Phosphorus and Nitrogen Cycle

ISSUES

• Sometimes we can get an excessive amount of Nitrogen and Phosphorus released into an environment
• This increase in nutrients can cause TOO much primary production
• EUTROPHICATION – excessive primary production causes so much algae growth that the lake becomes unable to support other organisms. The available oxygen gets depleted...fishkills may occur

What effects humans have: 

• Ozone Depletion
• Global Warming
• Acid Rain
• Endangered Species
• Eutrophication

The Ozone Layer 

• Ozone is a triatomic form of oxygen (O3) found in Earth’s upper and lower atmosphere about 15 to 30 km above the earth's surface.
• Ozone protects living organisms by absorbing harmful ultraviolet radiation (UVB) from the sun.
• The ozone layer is being destroyed by CFCs and other substances.
• Ozone depletion progressing globally except in the tropical zone.
• Leading to an increase in skin cancer.

CFC’s (Chlorofluorocarbons)

• These are found in:
• Aerosols like Hairspray
• Perfumes
• Paints
• Air Conditioner Refrigerants
• Pesticides
• Packing Materials

Selected Greenhouses gases 

• Carbon Dioxide (CO2)
• Source: Fossil fuel burning, deforestation
• Anthropogenic increase: 30%
• Average atmospheric residence time: 500 years

• Methane (CH4)
• Source: Rice cultivation, cattle & sheep ranching, decay from landfills, mining
• Anthropogenic increase: 145%
• Average atmospheric residence time: 7-10 years

• Nitrous oxide (N2O)
• Source: Industry and agriculture (fertilizers)
• Anthropogenic increase: 15%
• Average atmospheric residence time: 140-190 years

Greenhouse effect and Global Warming

•  The “greenhouse effect” & global warming are not the same things.
• Global warming refers to a rise in the temperature of the surface of the earth
• An increase in the concentration of greenhouse gases leads to an increase in the magnitude of the greenhouse effect. (Called enhanced greenhouse effect)
• This results in global warming

What is Acid Rain?

• Formed when gases, such as CO2 and SO2 react with the water in the atmosphere
• The pH of Raindrops As low as pH of 2
• Very harmful to our
• living environment

How does Acid rain affect us?
 

• It kills micro-organisms
• It poisons plants
• It damages metals and limestone
• It kills fish