sfsu geography 316 fall 2006 dr. barbara a....

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Nutrient Cycling I. A .Photosynthesis

B. Respiration C. ProductionPrimary productivityGross Production Net Production

II. Types of photosynthesisA. C3, B. C4, C. CAMD. Comparisons

III. General Carbon Cycle: Inputs and Outputs Human Impact

Joseph Priestly1772 experiment

PHOTOSYNTHESISConversion of light energy to chemical

energy, or the production of carbohydrates from carbon dioxide and water in the presence of chlorophyll. 6CO2 + 6H2O + (light) = C6H12O6+6O2

SFSU Geography 316 Fall 2006 Dr. Barbara A. Holzman

For the exclusive use of students enrolled in GEOG 316 Fall 2006

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What is Photosynthesis?Photosynthesis is the process by which plants,

some bacteria, and some protistans use the energy from sunlight to produce sugar, which cellular respiration converts into ATP, the "fuel" used by all living things. The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll. Most of the time, the photosynthetic process uses water and releases the oxygen. We can write the overall reaction of this process as:

6H2O + 6CO2 -------> C6H12O6+ 6O2

Photosynthesis6H2O + 6CO2 ----> C6H12O6+ 6O2

water + carbon dioxide

carbohydrate +oxygen

Green plants (w/chlorophyll) absorb light energy and use it to produce glucose from carbon dioxide and water releasing oxygen as a byproduct

Light energy

Six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen



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The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf.

Plants are the only photosynthetic organisms to have leaves (and not all plants have leaves). A leaf may be viewed as a solar collector crammed full of photosynthetic cells.

RESPIRATION:The rate at which energy is used to do work in an ecosystem, or the process by which organic compounds are transformed into gaseous CO2.

C6H12O6 +6O2 = 6CO2 + 6H2O + usable energy(heat)



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Types of Photosynthesis

C3 photosynthesis

C4 photosynthesis

CAM photosynthesis

C3– most widely distributed type of photosynthesis. Includes all algae and most vascular plants. C3 plants are best adapted to cool moist, moderate light conditions.

C4 occurs only in vascular plants, mostly grasses. C4 plants are best adapted to hot, dry sunny conditions. Commonly found in tropics



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CAM--crassulacean acid metabolism. Assimilation of CO2 occurs at night, and includes both C3 and C4 processes. CAM plants often have a reverse “stomatal rhythm” where their stomates are open at night and closed during the day.

Water loss is minimal.

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Comparisons between photosynthetic strategies

• C3,C4 photosynthesize during day• CAM at night• Amount of photosynthesis depends on

temperature: C3 cooler temperatures does best, C4 hotter climates does best

• C4 can take advantage of high light intensity, C3 levels out

PRODUCTION: the process of energy input and storage in ecosystems.

Gross Production: (PG) -- the energy input into the ecosystem. (total amount of carbohydrate produced)

Net Production: (PN) -- the energy storage in an ecosystem, or the rate of growth in the system. (the amount of carbohydrate remaining after respiration)

PN can be figured by the following formula: PN = PG - R



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Primary Productivity of Ecosystems

Net primary productivity (NPP)EstuariesEstuaries

Swamps and marshesSwamps and marshes

Tropical rain forestTropical rain forest

Temperate forestTemperate forest

Northern coniferous forest (taiga)Northern coniferous forest (taiga)

SavannaSavanna

Agricultural landAgricultural land

Woodland and Woodland and shrublandshrubland

Temperate grasslandTemperate grassland

Lakes and streamsLakes and streams

Continental shelfContinental shelf

Open oceanOpen ocean

Tundra (arctic and alpine)Tundra (arctic and alpine)

Desert scrubDesert scrub

Extreme desertExtreme desert

800800 1,6001,600 2,4002,400 3,2003,200 4,0004,000 4,8004,800 5,6005,600 6,4006,400 7,2007,200 8,0008,000 8,8008,800 9,6009,600

Average net primary productivity (kcal/mAverage net primary productivity (kcal/m22/yr)/yr)Fig. 4.25, p. 88

Fig. 4.24, p. 87

Earth’s gross primary productivity

Carbon cycle



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The Carbon Cycle (Terrestrial)

photosynthesisphotosynthesis aerobic aerobic respirationrespirationTerrestrial

rocks

Soil water(dissolved carbon)

Land food websproducers, consumers,

decomposers, detritivores

Atmosphere(mainly carbon dioxide)

Peat,fossil fuels

combustion of wood combustion of wood (for clearing land; (for clearing land;

or for fuelor for fuel

sedimentation

volcanic action

death, burial, compaction death, burial, compaction over geologic timeover geologic timeleaching leaching

runoffrunoff

weatheringweathering

Human Impacts

Human Impact



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Carbon cycle in the Ocean

The Carbon Cycle (Aquatic)Diffusion between

atmosphere and ocean

Carbon dioxidedissolved in ocean water

Marine food websproducers, consumers,

decomposers, detritivores

Marine sediments, includingformations with fossil fuels

combustion of fossil fuels

incorporation incorporation into sedimentsinto sediments

death, death, sedimentationsedimentation

uplifting uplifting over geologic over geologic

timetime sedimentationsedimentation

photosynthesisphotosynthesis aerobic aerobic respirationrespiration



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Nutrient Cycling I. Plants are large component of the carbon cycle

A .Photosynthesis 6H2O + 6CO2 ->light>- C6H12O6+ 6O2B. Respiration (C6H12O6 +6O2 = 6CO2 + 6H2O + usable energy(heat)C. Production

Primary productivyGross Production –respiration = Net Production

II. Types of photosynthesisA. C3 (common), C4(grasses), CAM (deserts)D. Comparisons

III. General Carbon Cycle: Inputs and Outputs Human Impact (terrestrial and aquatic)



sfsu geography 316 fall 2006 dr. barbara a....

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