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The Energy of Life Chapter 3 Elements Essential For Life Hydrogen: y g Organic g molecules Carbon: Organic molecules Nitrogen: Proteins and Nucleic Acids Oxygen: Organic molecules These elements account for 99% of the mass of all living g things. g Elements Essential For Life Na P K Mg S Ca Si Cl Fe These elements account for 1% of the mass of all living things. What Classifies Something As Li i ? Living? • • All organisms g consist of cells. Energy is necessary for life because living systems use it to accomplish the processes of life: 1. Reproduction 2. Growth 3. Movement 4 Eating 4. 5 Stimulus/Response 5. First Law of Thermodynamics: Energy cannot be created nor destroyed. Energy can only be changed from one form to another. Machines A combination of matter capable of using energy to perform useful work. A li Are living i things thi machines? hi ? Is a machine, like a submarine, a living thing? How Matter and Energy Enter Living S t Systems Autotrophy: p y the p process of self-feeding g by y creating g energy-rich compounds called Carbohydrates. Heterotrophy: p y the p process of obtaining g energy-rich gy organic compounds by consuming other plants and/or animals. Respiration The process of releasing energy from carbohydrates to perform f th the functions f ti off life. lif C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Photosynthesis Process of using g light g energy gy to create carbohydrates y from inorganic compounds. During photosynthesis, organisms use light energy to di disassemble bl carbon b dioxide di id and d water t molecules, l l rebuilding them into carbohydrates. Primary Producers = Autotrophs 6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2O Primary producers harness only about 1/2,000 of the light reaching Earth. Aerobic respiration: respiration that uses oxygen. Anaerobic respiration: respiration that does not use oxygen. yg Energy Cycle Chemosynthesis The p process of using g chemicals to create energy-rich gy organic compounds. Both photosynthesis and chemosynthesis are forms of fi ti – the fixation th process off converting, ti or fixing, fi i an inorganic compound into a useable organic compound. Carbohydrates y In 1977, scientists diving in ALVIN, discovered communities living g around volcanic springs. p g “cold-seep” communities: primitive single-cell organisms use methane from f seeps on the ocean bottom. This process traps a lot of potential carbon dioxide. Beggiatoal bacterial mat Tubeworms, soft corals and Tubeworms chemosynthetic mussels at a seep located 3,000 meters down Cold seep vs. Hydrothermal vents (cold vents) Cold seep Emissions are same temperature Emit at slow dependable rate Organisms are longer-lived Hydrothermal Emissions are super-heated Volatile and ephemeral environment Organisms are shorter-lived The Ocean’s Ocean s Primary Productivity In the marine environment, two variables affect the availability of energy. 1). Quantity of Primary Production 2). Flow of Energy Marine Biomass The main “products” p of primary p y production p are carbohydrates. Carbohydrates are the primary units of usable energy i living in li i systems, t plus l a source off carbon b used d in i an organism’s tissues. Scientists measure primary productivity In terms of the carbon fixed (bound) into organic material. The unit of measurement of primary productivity is: grams of Carbon per square meter of surface area per year. gC/m2/yr The oceans’ oceans primary productivity averages from 75 to 150gC/m2/yr Biomass: the mass of living tissue. Standing Crop: the biomass at a given time. The image shows ocean net primary productivity distributions from the Sea Sea-viewing viewing Wide Field Field-ofof view Sensor (SeaWiFS) data on the OrbView-2 satellite (1997-2002). The units are in grams of Carbon per meter squared per year. Light gray areas indicate missing data. Credit: Images by Robert Simmon, NASA GSFC Earth Observatory, based on data provided by Watson Ocean Community All oceans – average Net Primary Productivity 120 Coral reef 880 - 2,200 Kelp bed 400 – 1,900 Sh lf plankton Shelf l kt 90 – 270 Open ocean 1 - 180 Typically, the standing crop in the oceans is one to two billion metric tons. Land Community All Land – average Net Primary Productivity 150 Rain Forest 460 – 1,600 Temperate Forest 270 – 1,140 F Freshwater h t Swamp S 360 – 1,820 1 820 Cropland 45 – 1,820 Typically the standing crop on land is 600 to 1,000 billion metric tons tons. Turnover: the time required for the photosynthesis/ respiration cycle in an ecosystem. The shorter the turnover time, the faster the standing crop passes energy into the ecosystem. ecosystem Gross Primary Productivity (GPP): the measure of all the organic material produced in an area by autotrophs. Net Primary Productivity (NPP): the quantity of energy remaining after autotrophs have satisfied their respiratory needs. Plankton A group organisms that exist adrift in ocean currents. 2 types: 1. phytoplankton (plants) 2. zooplankton (animals) Nekton: organisms that swim, from small invertebrates to large whales whales. Benthos: organisms that live in or on the bottom. They can move about or be sessile. Neuston: plankton that float on the surface. Neuston Phytoplankton Nekton Benthos Zooplankton Diatoms 4 types yp of p phytoplakton: y p • • • • 1. Diatoms: the most efficient photosynthesizers known. The most dominant and productive of the phytoplankton. Characterized by a rigid cell wall made of silica. Cell wall wall, called a frustule frustule, admits light much like glass glass. 2. Dinoflagellates: – characterized one or two whip-like flagella which they move to change orientation or swim vertically in water. – Most are autotrophs. – Some live within coral polyps and are the most significant primary producers in the coral reef community community. – Principal organisms responsible for plankton blooms because of their high reproductive rates. 3. Coccolithophores: – – – – single-celled single celled autotrophs characterized by shells of calcium carbonate. Shells are called coccoliths. Li in Live i brightly b i htl lit, lit shallow h ll water. t Area with high concentrations may appear milky or chalky. 4. Silicoflagellates: – charaterized by internal supporting structures made of silica. – Propel themselves with one long flagellum. – Structurally St t ll and d chemically h i ll more primitive i iti than th diatoms. di t Benthos 3 divisions: 1. epifauna – those animals that live on the sea floor. 2. epiflora – those plants that live on the sea floor. floor 3. infauna – organisms that are partially or completely buried on the sea floor. Infauna can be: 1. Deposit feeders: feed off detritus (loose organic or inorganic material) drifting down from above 2. Suspension feeders: filter particles (mostly plankton) l kt ) suspended d d in i the th water t for f food. f d Limits on Marine Primary P d ti it Productivity Limiting g factors: p physiological y g or biological g necessities that restrict survival. Too much or too little will reduce the population of an organism. i 4 Limiting factors Depth p Light Plankton Bloom Location Plankton Bloom • Periods of explosive p reproduction p and growth g of a particular plankton species. • Can deplete the nutrients available in a region. • In extreme cases, they consume all the oxygen and release toxic by-products in such amounts that fish and other organisms cannot survive. • Known as “red tides.” • Can occur naturally, but they may also be caused when pollution eliminates a limiting factor. Depth • Can limit nutrients. Dead organisms that would normally provide nutrients can sink below depths that sunlight can’t can t reach, making their nutrients unavailable to photosynthesizers. • Solution occurs when normal water motion brings the nutrients back to shallow water. • Water temperatures can interfere with normal mixing. mixing • Waters of different temperatures resist mixing because they have different densities. • Also affects photosynthesis and primary productivity. • Photoinhibition: the condition in which excess light overwhelms an autotroph. • Even in clear water, little photosynthesis takes place below 100 meters (328 feet). Some autotrophs cannot photosynthesize when the water is too shallow. Different phytoplankton species h have different diff t optimal ti l depths. d th The less light there is, the less photosynthesis occurs, reducing carbohydrate production. As you go deeper autotrophs produce less carbohydrates. • Tropical waters tend to have less productivity. Warm upper water layer traps nutrients in the cold layers that are too deep for photosynthesizing autotrophs. • In the Artic and Antarctic, there’s little temperature differences between shallow and deep waters. This allows nutrients to cycle to shallower water more easily. • In temperate regions, coastal areas tend to have more primary productivity. There are more nutrients f from rain i runoff ff and d because b shallow h ll waters t keeps k them from sinking below the productive zone. Location Coral Reefs: • The most efficient ecosystems on Earth. • rely l on dinoflagellates di fl ll t that th t live li within ithi the th corall tissue rather than phytoplankton. • Exception to the rule of low productivity of tropical waters. • Recycles its nutrients efficiently with very little loss t the to th open sea. Antarctic Convergence Zone: • Some of the highest productivity. Can be well over 200 C/ 2/yr. 200gC/m / How? Long summer days water movement bringing nutrients to shallow water mineral runoff • Short summer season makes high productivity short-lived. • Arctic doesn’t have comparable productivity intervals. It lacks landmass so fewer minerals in Arctic waters. Light • Seasonal sunlight limits productivity. • The amount of daylight affects photosynthesis and primary productivity productivity. Compensation Depth The p point of zero net primary p y productivity p y where the amount of carbohydrates produced exactly equals the amount required by the autotrophs for respiration. respiration • Varies with water clarity, surface disturbances, and sun angle. How does this affect a food chain/food web? Energy Flow Through the Bi Biosphere h Energy enters E t li living i systems t and d the th biosphere through the primary production of _____________. p _____________ _____________ get their energy from consuming autotrophs or other ___________. Autotrophs Heterotrophs Tropic Pyramid A representation p of how energy gy transfers from one level of organisms to the next as they consume each other. 10% rule Food Webs Shows that organisms g often have different choices of prey and eat across the trophic pyramid’s theoretical levels. Decomposition • Completes p the materials cycle y • Renews the inorganic materials (matter) necessary for energy to enter life through primary production. • Bacteria and archaea are the most important decomposers. • On average, average there are 108 bacteria per liter of seawater.