Cell Energy SUN ENERGY SUGAR ATP(ENERGY) LIFE’S ACTIVITIES PHOTOSYNTHESIS RESPIRATION SUGAR ATP(ENERGY)

SUN The ultimate source of energy on Earth

How do AUTOTROPHS get energy to live?

AUTOTROPHS Use energy from the sun to make their own food by doing photosynthesis

What organelle does photosynthesis take place in? Plant cells take energy from the sun and turn it into food This Takes place in the chloroplast of cells What organelle does photosynthesis take place in?

What do Plants need to do PHOTOSYNTHESIS? What do Plants make when they do PHOTOSYNTHESIS?

EQUATION FOR PHOTOSYNTHESIS WATER OXYGEN CO2 + H2O + ENERGY C6H12O6 + O2 CARBON DIOXIDE GLUCOSE

What affects the rate of PHOTOSYNTHESIS ? Water Carbon Dioxide Light Intensity Temperature

HETEROTROPHS Cannot get energy directly from the sun Eat food to get energy

How do organisms get ENERGY from food?

What organelle does cellular respiration take place in? All cells take food and turn it into energy the organism can use Takes place in the mitochondria of cells What organelle does cellular respiration take place in?

EQUATION FOR RESPIRATION CARBON DIOXIDE ATP GLUCOSE C6H12O6 + O2 CO2 + H2O + ENERGY OXYGEN WATER

How Does the Equation for PHOTOSYNTHESIS Relate to the Equation for CELLULAR RESPIRATION?

How Does the Equation for PHOTOSYNTHESIS CO2 + CARBON DIOXIDE Relate to the Equation for CELLULAR RESPIRATION? CARBON DIOXIDE CO2 +

How Does the Equation for PHOTOSYNTHESIS WATER CO2 + H2O + CARBON DIOXIDE Relate to the Equation for CELLULAR RESPIRATION? CARBON DIOXIDE CO2 + H2O + WATER

How Does the Equation for PHOTOSYNTHESIS WATER CO2 + H2O + ENERGY CARBON DIOXIDE Relate to the Equation for CELLULAR RESPIRATION? CARBON DIOXIDE ATP CO2 + H2O + ENERGY WATER

How Does the Equation for PHOTOSYNTHESIS C6H12O6 + GLUCOSE Relate to the Equation for CELLULAR RESPIRATION? GLUCOSE C6H12O6 +

How Does the Equation for PHOTOSYNTHESIS OXYGEN C6H12O6 + O2 GLUCOSE Relate to the Equation for CELLULAR RESPIRATION? GLUCOSE C6H12O6 + O2 OXYGEN

How Does the Equation for PHOTOSYNTHESIS CO2 + H2O + ENERGY C6H12O6 + O2 CARBON DIOXIDE WATER GLUCOSE OXYGEN Relate to the Equation for CELLULAR RESPIRATION? C6H12O6 + GLUCOSE O2 OXYGEN CO2 + CARBON DIOXIDE H2O + ENERGY WATER ATP

How Does the Equation for PHOTOSYNTHESIS Relate to the Equation for CELLULAR RESPIRATION? The reactants used in photosynthesis are the products made in cellular respiration The products made in photosynthesis are the reactants used in cellular respiration

Ch. 54 - Ecosystems Overview: Ecosystems, Energy, and Matter An ecosystem consists of all the organisms living in a community as well as all the abiotic factors with which they interact

Ecosystems can range from a microcosm, such as an aquarium to a large area such as a lake or forest Figure 54.1

Regardless of an ecosystem’s size its dynamics involve two main processes: energy flow chemical cycling Energy flows through ecosystems while matter cycles within them Ecosystems are transformers of energy and processors of matter

Laws of Thermodynamics 1st Law – Energy cannot be created or destroyed, but it can be transferred from one form to another. Photosynthesis Light  Chemical Cellular Respiration (processing food) Chemical  Chemical Life’s Activities Chemical  Thermal 2nd Law – As energy moves through a system the amount of usable energy decreases. Rule of 10 As energy moves through an ecosystem, only 10% of usable energy is passed to the next trophic level.

How organisms get energy The ultimate source of energy on Earth is the Sun Autotrophs-get energy from the sun to make food Heterotrophs-must eat other organisms to get energy Carnivores Omnivores Herbivores Detrivores

Trophic Levels (feeding steps) Producers-Autotrophs Mostly Plants Primary Consumers-1st order heterotrophs Eat Producers (herbivores) Secondary Consumers-2nd order heterotrophs Eat Primary Consumers Tertiary Consumers-3rd order heterotrophs Eat Secondary Consumers (top predators)

Energy flows through an ecosystem Entering as light and exiting as heat Figure 54.2 Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow

Detritivores, mainly bacteria and fungi, recycle essential chemical elements by decomposing organic material and returning elements to inorganic reservoirs Figure 54.3

Primary production in an ecosystem is the amount of light energy converted to chemical energy by autotrophs during a given time period Photosynthesis determines the energy budget of the entire ecosystem

Gross and Net Primary Production The ecosystem’s gross primary production (GPP) is the total primary production Not all of this production is stored as organic material in the growing plants Net primary production (NPP) is equal to GPP minus the energy used by the primary producers for respiration Only NPP is available to consumers

Different ecosystems vary considerably in their net primary production and in their contribution to the total NPP on Earth Lake and stream Open ocean Continental shelf Estuary Algal beds and reefs Upwelling zones Extreme desert, rock, sand, ice Desert and semidesert scrub Tropical rain forest Savanna Cultivated land Boreal forest (taiga) Temperate grassland Tundra Tropical seasonal forest Temperate deciduous forest Temperate evergreen forest Swamp and marsh Woodland and shrubland 10 20 30 40 50 60 500 1,000 1,500 2,000 2,500 5 15 25 Percentage of Earth’s net primary production Key Marine Freshwater (on continents) Terrestrial 5.2 0.3 0.1 4.7 3.5 3.3 2.9 2.7 2.4 1.8 1.7 1.6 1.5 1.3 1.0 0.4 125 360 3.0 90 2,200 900 600 800 700 140 1,600 1,200 1,300 250 5.6 1.2 0.9 0.04 22 7.9 9.1 9.6 5.4 0.6 7.1 4.9 3.8 2.3 65.0 24.4 Figure 54.4a–c Percentage of Earth’s surface area (a) Average net primary production (g/m2/yr) (b) (c)

Overall, terrestrial ecosystems Contribute about two-thirds of global NPP and marine ecosystems about one-third Figure 54.5 180 120W 60W 0 60E 120E North Pole 60N 30N Equator 30S 60S South Pole

Primary Production in Marine and Freshwater Ecosystems In marine and freshwater ecosystems both light and nutrients are important in controlling primary production The depth of light penetration affects primary production throughout the photic zone of an ocean or lake Nitrogen and phosphorous are typically the nutrients that most often limit marine production

In some areas, sewage runoff which has caused eutrophication of lakes, which can lead to the eventual loss of most fish species from the lakes Figure 54.7

Primary Production in Terrestrial and Wetland Ecosystems In terrestrial and wetland ecosystems climatic factors such as temperature and moisture, affect primary production on a large geographic scale

Actual evapotranspiration The contrast between wet and dry climates can be represented by a measure called evapotranspiration Actual evapotranspiration Is the amount of water annually transpired by plants and evaporated from a landscape Is related to net primary production Figure 54.8 Actual evapotranspiration (mm H2O/yr) Tropical forest Temperate forest Mountain coniferous forest Temperate grassland Arctic tundra Desert shrubland Net primary production (g/m2/yr) 1,000 2,000 3,000 500 1,500

Live, above-ground biomass On a more local scale a soil nutrient is often the limiting factor in primary production Figure 54.9 EXPERIMENT Over the summer of 1980, researchers added phosphorus to some experimental plots in the salt marsh, nitrogen to other plots, and both phosphorus and nitrogen to others. Some plots were left unfertilized as controls. RESULTS Experimental plots receiving just phosphorus (P) do not outproduce the unfertilized control plots. CONCLUSION Live, above-ground biomass (g dry wt/m2) Adding nitrogen (N) boosts net primary production. 300 250 200 150 100 50 June July August 1980 N  P N only Control P only These nutrient enrichment experiments confirmed that nitrogen was the nutrient limiting plant growth in this salt marsh.

Energy transfer between trophic levels is usually less than 20% efficient The secondary production of an ecosystem is the amount of chemical energy in consumers’ food that is converted to their own new biomass When a caterpillar feeds on a plant leaf only about one-sixth of the energy in the leaf is used for secondary production Plant material eaten by caterpillar Cellular respiration Growth (new biomass) Feces 100 J 33 J 200 J 67 J

The production efficiency of an organism Is the fraction of energy stored in food that is not used for respiration Trophic efficiency Is the percentage of production transferred from one trophic level to the next Usually ranges from 5% to 20%

Pyramids of Production This loss of energy with each transfer in a food chain can be represented by a pyramid of net production Figure 54.11 Tertiary consumers Secondary Primary producers 1,000,000 J of sunlight 10 J 100 J 1,000 J 10,000 J

One important ecological consequence of low trophic efficiencies can be represented in a biomass pyramid Most biomass pyramids show a sharp decrease at successively higher trophic levels Figure 54.12a (a) Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida. Trophic level Dry weight (g/m2) Primary producers Tertiary consumers Secondary consumers Primary consumers 1.5 11 37 809

Number of individual organisms Pyramids of Numbers A pyramid of numbers represents the number of individual organisms in each trophic level Figure 54.13 Trophic level Number of individual organisms Primary producers Tertiary consumers Secondary consumers Primary consumers 3 354,904 708,624 5,842,424

The dynamics of energy flow through ecosystems have important implications for the human population Eating meat is a relatively inefficient way of tapping photosynthetic production

Worldwide agriculture could successfully feed many more people if humans all fed more efficiently, eating only plant material Trophic level Secondary consumers Primary producers Figure 54.14

Life on Earth depends on the recycling of essential chemical elements Nutrient circuits that cycle matter through an ecosystem involve both biotic and abiotic components and are often called biogeochemical cycles

Biogeochemical Cycles The water cycle and the carbon cycle Figure 54.17 Transport over land Solar energy Net movement of water vapor by wind Precipitation over ocean Evaporation from ocean Evapotranspiration from land Percolation through soil Runoff and groundwater CO2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary Detritus Carbon compounds in water Decomposition THE WATER CYCLE THE CARBON CYCLE

The nitrogen cycle and the phosphorous cycle Figure 54.17 N2 in atmosphere Denitrifying bacteria Nitrifying Nitrification Nitrogen-fixing soil bacteria bacteria in root nodules of legumes Decomposers Ammonification Assimilation NH3 NH4+ NO3 NO2  Rain Plants Consumption Decomposition Geologic uplift Weathering of rocks Runoff Sedimentation Plant uptake of PO43 Soil Leaching THE NITROGEN CYCLE THE PHOSPHORUS CYCLE

Decomposition and Nutrient Cycling Rates Decomposers (detritivores) play a key role in the general pattern of chemical cycling Figure 54.18 Consumers Producers Nutrients available to producers Abiotic reservoir Geologic processes Decomposers