Cycles of Matter
What Molecules do Organisms Need?
How do Organisms Get Those Molecules?
Cycling of MATTER in Ecosystems Organisms need energy AND matter to
survive
Ex: molecules to build bones, muscle, fat While energy flows in one direction,
matter recycles in ecosystems The most important molecules that
recycle are water, carbon, nitrogen, phosphorus and oxygen
The Water Cycle
Water is necessary for organisms to maintain an internal balance and to transport molecules like sugars and enzymes
Water is a renewable resource that we access through a water shed
Water shed = area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater
The Water Cycle
Transpiration
Evaporation
Precipitation
Condensation
Runoff
The Carbon Cycle
Required for all living organisms on earth Needed to make DNA, proteins, fats,
sugars In nature, found as CO2 (gas) and many
solids (in alive and dead organisms) Photosynthesis and respiration are key
processes to keeping the cycle going
Photosynthesis and RespirationPhotosynthesis (by plants)
CO2 + H2O C6H12O6 + O2
Respiration (by most organisms)
C6H12O6 + O2 CO2 + H2O
Carbondioxide Water Sugar Oxygen
sunlight
Carbondioxide WaterSugar Oxygen
Photosynthesis and Respiration
Matter CYCLES back and forth between photosynthesis and respiration.
This is where oxygen is recycled, too!
The Carbon Cycle
Nitrogen Cycle
Nitrogen is a key component of proteins and DNA
Nitrogen is present as gas in the atmosphere (N2), and must be turned into a solid (NH3, NH4) by bacteria for plants to use it
Fixing gas into solid = nitrogen fixation Changing solid back into gas = denitrification
Nitrogen Cycle
The Phosphorus Cycle
Phosphorus is an important building block of DNA; all living things must have phosphorus
Phosphorus is found in rocks, and enters food webs when plants take up phosphorus found in soil
Phosphorus Cycle
Water and pH
Water has a pH of 7 pH is a scale which determines how acidic or
basic a substance is Below 7 = acid Above 7 = base
pH Scale
The pH Scale
Water can split into equal numbers of OH- and H+ ions
The pH scale compares everything to water Acidic substances (pH under 7) have more
H+ ions than OH- ions Basic substances (pH above 7) have more
OH- ions than H+ ions
Homework Sec. 3.3, 4.1 and 4.2 (BP, NG, get/don’t get for
each section)
Bring warm clothes and shoes that can get dirty we will be walking to the pond on Wednesday/Thursday and Friday
Mini- Quiz on Wednesday/Thursday Levels of organization (individual to biosphere) Trophic levels (energy flow) Difference between food chain and a food web
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