BIO 4730/5730 Environmental Biology Topic 3 Energy and Energetics Energy and Energy Metabolism ■ Energy is required for: Energy Availability on Earth ● Resisting entropy and maintaining ■ Energy is measured in joules (J) homeostasis Most of energy intake ● 1 J = 0.239 calories (actually, a gram-calorie, 1 g-cal = 4.186 J) (about 90%) is needed for this maintenance metabolism (supporting ● 1 kiloJoule (kJ) = 1000 Joules existing biological material) ● 1 megaJoule (MJ) = 1,000,000 J ■ Most adaptations are directly or ■ A calorie is the amount of energy required to increase the indirectly associated with maintaining temperature of 1 g water 1 °C at 15 °C homeostasis while increasing energy ● A kilocalorie (kcal) or Calorie = 1000 calories gain or decreasing energy wastage ■ Energy transfer requires the movement or flow of ■ Organisms must also produce new biological material (biomass). Any energy from one point to the other (energy flux = energy that is assimilated but not power) needed for maintenance is available -1 ● Unit of power (energy/time) is the watt (W) = 1 J s for: -2 ● Earth receives and average of about 1 W m on its sunlit side ● Somatic (body) growth (ultimate limit to global energy input) ● Reproduction ● Humans supplement solar energy using stored energy reserves ■ This increase in biomass by growth and (fossil fuels) deposited over 100s of millions of years reproduction is known as production
Earth Area Available to Support Humans Energetics and Thermodynamics Productive sea Energy is the ability to do work, and is the ultimate and land area limiting resource for all living things available to support each First law of thermodynamics (Law of Conservation of person in Africa: Energy): energy can be neither created or destroyed, only 1.36 ha converted from one form to another (energy input = …on Earth: 1.90 ha energy output)
Each W. European/U.S. citizen: World 5.06/5.26 ha Wildlife Productive sea and land area needed to produce Fund, None of these ‘devourings’ creates any new Living Planet energy, they just pass along energy that came the products consumed by each U.S. citizen: from somewhere else. Where do you think the 9.71 ha (the CSU campus is 64.75 ha: enough to Report 2002. energy used by the organisms above comes sustain 12.3 U.S. citizens) from?
Energetics and Thermodynamics Energy Sources for Ecosystems Sunlight is generally considered to be the major ‘ ’ Second law of thermodynamics ( Law of Entropy ): energy energy source powering ecosystems transformations are not completely efficient ■ Only a small proportion of incoming solar ■ Whenever energy is used to do energy is captured by living organisms during work, some energy is lost as heat photosynthesis 30% ■ Result is that all complex systems 50% ■ In cells of photosynthetic organisms, reflected converted 19% powers tend toward increasing disorder to heat water cycle a series of enzymes converts CO2 and (entropy) H2O into a sugar (glucose), which can ■ Thus, all levels of life (organisms to ecosystems) require be stored energy inputs to maintain their structure and function
1% powers Less than 15% of the original photosynthesis chemical energy contained in gasoline actually moves the car
Eating is also inefficient: only a CO2 + H2O → Energy to break and form the necessary fraction of the chemical energy CH2O + O2 chemical bonds comes from light photons at in food is used by the consumer certain specific wavelengths of sunlight. Molecular oxygen is released as a byproduct
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Ecological (Biomass) Production Energy-bearing Nutrients and Respiration Primary Production: Cells use many organic molecules as fuel for respiration: ■ Production of autotroph (producer) biomass ■ Autotrophs capture and store their own energy and synthesize their own structural materials ■ Limited by photosynthetic rates Secondary Production: ■ Production of heterotroph