The Energy of Life Chapter 3

Transcription

1 The Energy of Life Chapter 3

2 Elements Essential For Life Hydrogen: Organic molecules Carbon: Organic molecules Nitrogen: Proteins and Nucleic Acids Oxygen: Organic molecules These elements account for 99% of the mass of all living things.

3 Elements Essential For Life Na Mg Si P S Cl K Ca Fe These elements account for 1% of the mass of all living things.

4 What Classifies Something As Living? i All organisms 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 5. Stimulus/Response First Law of Thermodynamics: Energy cannot be created nor destroyed. Energy can only be changed from one form to another.

5 Machines A combination of matter capable of using energy to perform useful work. Are living i things machines? Is a machine, like a submarine, a living thing?

6 How Matter and Energy Enter Living Systems Autotrophy: the process of self-feeding by creating p y p g y g energy-rich compounds called Carbohydrates.

7 Heterotrophy: the process of obtaining energy-rich p y p g gy organic compounds by consuming other plants and/or animals.

8 Respiration The process of releasing energy from carbohydrates to perform the functions of life. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + energy

9 Photosynthesis Process of using light energy to create carbohydrates from inorganic compounds. During photosynthesis, organisms use light energy to disassemble carbon dioxide id and water molecules, l rebuilding them into carbohydrates. Primary Producers = Autotrophs 6CO H 2 O + sunlight ---> 6O 2 + C 6 H 12 O 6 + 6H 2 O

10 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.

11 Energy Cycle

12 Chemosynthesis The process of using chemicals to create energy-rich organic compounds. Both photosynthesis and chemosynthesis are forms of fixation the process of converting, or fixing, i an inorganic compound into a useable organic compound. Carbohydrates

13 In 1977, scientists diving in ALVIN, discovered communities living around volcanic springs. cold-seep communities: primitive single-cell organisms use methane from seeps on the ocean bottom. This process traps a lot of potential carbon dioxide. Beggiatoal bacterial mat Tubeworms, soft corals and chemosynthetic mussels at a seep located 3,000 meters down

14 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

15 The Ocean s Primary Productivity In the marine environment, two variables affect the availability of energy. 1). Quantity of Primary Production 2). Flow of Energy

16 Marine Biomass The main products of primary production are carbohydrates. Carbohydrates are the primary units of usable energy in living i systems, plus a source of carbon used in 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/m 2 /yr The oceans primary productivity averages from 75 to 150gC/m 2 /yr

17 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 viewing Wide Field of The image shows ocean net primary productivity distributions from the Sea-viewing Wide Field-ofview Sensor (SeaWiFS) data on the OrbView-2 satellite ( ). 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

18 Ocean Community All oceans average 120 Net Primary Productivity Coral reef 880-2,200 Kelp bed 400 1,900 Shelf plankton Open ocean Typically, the standing crop in the oceans is one to two billion metric tons.

19 Land Community All Land average 150 Net Primary Productivity Rain Forest 460 1,600 Temperate Forest 270 1,140 Freshwater Swamp 360 1,820 Cropland 45 1,820 Typically the standing crop on land is 600 to 1,000 billion metric tons.

20 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. 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.

21 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. Benthos: organisms that live in or on the bottom. They can move about or be sessile. Neuston: plankton that float on the surface.

22 Neuston Phytoplankton Nekton Zooplankton Benthos

23 Diatoms 4 types of phytoplakton: 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, called a frustule, admits light much like glass.

24 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. Principal organisms responsible for plankton blooms because of their high reproductive rates.

25 3. Coccolithophores: single-celled autotrophs characterized by shells of calcium carbonate. Shells are called coccoliths. Live in brightly lit, shallow water. Area with high concentrations may appear milky or chalky.

26 4. Silicoflagellates: charaterized by internal supporting structures made of silica. Propel themselves with one long flagellum. Structurally t and chemically more primitive iti than diatoms.

27 Benthos 3 divisions: 1. epifauna those animals that live on the sea floor. 2. epiflora those plants that live on the sea floor. 3. infauna organisms that are partially or completely buried on the sea floor.

28 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) suspended d in the water for food.

29 Limits on Marine Primary Productivity it Limiting factors: physiological or biological necessities that restrict survival. Too much or too little will reduce the population of an organism. 4 Limiting factors Depth Light Plankton Bloom Location

30 Plankton Bloom Periods of explosive reproduction and growth 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.

31

32 Depth Can limit nutrients. Dead organisms that would normally provide nutrients can sink below depths that sunlight 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. Waters of different temperatures resist mixing because they have different densities.

33 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 have different optimal depths. The less light there is, the less photosynthesis occurs, reducing carbohydrate production. As you go deeper autotrophs produce less carbohydrates.

34 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 from rain runoff and because shallow waters keeps them from sinking below the productive zone.

35 Location Coral Reefs: The most efficient ecosystems on Earth. rely on dinoflagellates ll that t live within the coral tissue rather than phytoplankton. Exception to the rule of low productivity of tropical waters. Recycles its nutrients efficiently with very little loss to the open sea.

36 Antarctic Convergence Zone: Some of the highest productivity. Can be well over 200gC/m 2 /yr. 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.

37 Light Seasonal sunlight limits productivity. The amount of daylight affects photosynthesis and primary productivity.

38 Compensation Depth The point of zero net primary productivity where the amount of carbohydrates produced exactly equals the amount required by the autotrophs for respiration. Varies with water clarity, surface disturbances, and sun angle. How does this affect a food chain/food web?

39 Energy Flow Through the Biosphere Energy enters living i systems and the biosphere through the primary production of. Autotrophs get their energy from consuming autotrophs or other. Heterotrophs

40 Tropic Pyramid A representation of how energy transfers from one level of organisms to the next as they consume each other. 10% rule

41 Food Webs Shows that organisms often have different choices of g prey and eat across the trophic pyramid s theoretical levels.

42 Decomposition Completes the materials cycle Renews the inorganic materials (matter) necessary for energy to enter life through primary production. Bacteria and archaea are the most important decomposers. On average, there are 10 8 bacteria per liter of seawater.