Chapter 7

1. Chapter 7 Nutrients and Energy

4. Organisms can be classified by trophic levels. Autotrophs use inorganic sources of carbon and energy. Photosynthetic: Use CO2 as carbon source, and sunlight as energy. Chemosynthetic: Use inorganic molecules (CO2) as source of carbon and hydrogen sulfide (H2S) as energy. Heterotrophs use organic molecules as sources of carbon and energy. Energy Sources

7. 1977 - Organisms found living on sea floor. Near nutrients discharged from volcanic activity through oceanic rift. Chemosynthetic: Use inorganic molecules (CO2) as source of carbon and hydrogen sulfide (H2S) as energy to synthesize organic matters Autotrophsdepend on chemosynthetic bacteria. Free-living forms. Living within tissue of invertebrates. Using Inorganic Molecules

8. 影片

9. Nitrogen uptake

10. Nitrogen uptake

11. Three Feeding Methods of Heterotrophs: Herbivores: Feed on plants. Carnivores: Feed on animal flesh. Detritivores: Feed on non-living organic matter. Using Organic Molecules

12. Herbivores

13. Substantial nutritional chemistry problems.Low nitrogen concentrations.

15. Must overcome plant physical and chemical defenses. Physical Cellulose; lignin; silica Chemical Toxins Digestion Reducing Compounds Herbivores

19. Detritivores: Consume food rich in carbon and energy, but poor in nitrogen.

21. Consume nutritionally-rich prey. Cannot choose prey at will. Prey Defenses: Aposomatic Coloring - Warning colors. Mullerian mimicry: Comimicry among several species of noxious organisms. Batesian mimicry: Harmless species mimic noxious species. Carnivores

22. A wasp mimics a bee A fly mimics a bee

23. Predators are usually selection agents for refined prey defense. Usually eliminate more conspicuous members of a population (less adaptive). Must catch and subdue prey - size selection. Predator and prey species are engaged in a co-evolutionary race. Carnivores

25. The end

27. Optimal Foraging in Bluegill Sunfish

28. Limits on potential rate of energy intake by animals have been demonstrated by studying relationship between feeding rate and food availability. Limits on potential rate of energy intake by plants have been demonstrated by studying response of photosynthetic rate to photon flux density. Energy Limitation

29. Rate of photosynthesis increases linearly with photon flux density at low light intensities, rises more slowly with intermediate light intensities, and tends to level off at high light intensities. Response curves for different species generally level off at different maximum photosynthesis rates. Photon Flux and Photosynthetic Response Curves

31. Holling described (3) basic functional responses: 1. Feeding rate increases linearly as food density increases - levels off at maximum. Consumers require little or no search and handling time. 2. Feeding rate rises in proportion to food density. Feeding rate partially limited by search/handling time. Food Density and Animal Functional Response

32. 3. Feeding rate increases most rapidly at intermediate densities (S-shaped). Food Density and Animal Functional Response

33. Assures if energy supplies are limited, organisms cannot simultaneously maximize all life functions. Must compromise between competing demands for resources. Principle of Allocation Optimal Foraging Theory

34. All other things being equal,more abundant prey yields larger energy return. Must consider energy expended during: Search for prey Handling time Tend to maximize rate of energy intake. Optimal Foraging Theory

35. Limited supplies of energy for allocation to leaves, stems and roots. Bloom suggested plants adjust allocation in such a manner that all resources are equally limited. Appear to allocate growth in a manner that increases rate of acquisition of resources in shortest supply. Optimal Foraging By Plants

36. Energy Sources Solar-Powered Biosphere Photosynthetic Pathways Using Organic Molecules Chemical Composition and Nutrient Requirements Using Inorganic Molecules Energy Limitation Food Density and Animal Functional Response Optimal Foraging Theory Review

45. Light propagates through space as a wave. Photon: Particle of light bears energy. Infrared (IR) Long-wavelength, low energy. Interacts with matter, increasing motion. Ultraviolet (UV) Short wavelength, high energy. Can destroy biological machinery. Photosynthetically Active Radiation (PAR) Between two extremes. Solar - Powered Biosphere

46. Photosynthetically Active Radiation

47. PAR Quantified as photon flux density. Number of photons striking square meter surface each second. Chlorophyll absorbs light as photons. Landscapes, water, and organisms can all change the amount and quality of light reaching an area. Solar - Powered Biosphere

48. C3 Photosynthesis Used by most plants and algae. CO2 + ribulose bisphosphate (5 carbon sugar) = phosphoglyceric acid (3 carbon acid) To fix carbon, plants must open stomata to let in CO2 . Water gradient may allow water to escape. Photosynthetic Pathways

49. C3 Photosynthesis

50. C4 Photosynthesis Reduce internal CO2 concentrations. Increases rate of CO2 diffusion inward. Need fewer stomata open. Conserving water Acids produced during carbon fixation diffuse to specialized cells surrounding bundle sheath. Photosynthetic Pathways