Intro to Energy and Laws of thermodynamics Ecosystem Energy Flow Intro to Energy and Laws of thermodynamics

Thermodynamics Thermodynamics are the principles that govern energy relationships Describe constraints on the generation of heat Transformations of energy Energy transfer within a system or to the surroundings If energy is added to a system from its surroundings; might return to surroundings in a different form 1st law thermodynamics Energy is conserved when both a system and its surroundings are considered It’s not created nor destroyed but transformed from one form to another

Thermodynamics 2nd law of thermodynamics (law of entropy) In any energy transformation, some energy is lost as unusable energy in the sense that work cannot be performed Energy in enviro sci class looks at these 2 ?s Where does the energy needed for living organisms originate? How is energy used by these organisms?

Where does ENERGY start? Think of surface of earth as a system subject to the first 2 laws of thermodynamics Electromagnetic radiation from the sun ~58% of radiation directed toward earth is reflected or absorbed as heat by out atmosphere Less then 2% of remaining radiation is used by plants The balance is transformed into heat Energy released by geothermal and volcanic activity

Living things Living organisms are temporary storage units for useful energy One organism can be used by another as a source of energy In transfer, energy is lost to environment as heat We need to have continuous energy enter the system Photosynthesizing organisms go thru oxidation-reduction reactions based on solar input to produce and store own carbohydrates; which then become energy for other organisms

Ecosystems and Energy Food consumed undergoes chem reactions known as metabolism Chemosynthesis – inorganic compounds (nitrites, hydrogen sulfide, hydrogen gas) provide the necessary energy for organisms to make own food Photosynthesis Green plants produce ATP (carrier for energy) and NADPH (carrier for e- used in synthesis of glucose) in their chloroplasts Add CO2 and H2O Now forma carbohydrate (glucose) in presence of sunlight and chlorophyll

Energy in Ecosystem Cellular Respiration Trophic Levels CO2, H2O and energy are produced by the oxidation of glucose Requires oxygen and occurs in mitochondria Trophic Levels Each step in the transfer of energy (autotroph to heterotroph and heterotroph to heterotroph) is a trophic level Laws of thermodynamics apply to energy flow; less energy is available to organisms at each higher trophic level Estimated that only 10% of energy at each trophic level is available to organisms at the next higher level

Energy in Ecosystem Food chains and webs Ecological Pyramids Lowest level – autotrophs/producers Primary consumers – herbivores Secondary consumers – carnivores that eat the herbivores Ecological Pyramids Base = producers Each trophic level above is some level of consumer 3 types: energy, numbers, and biomass

Ecological Pyramids Energy Biomass Levels Shows decreasing amount of energy available to each successive trophic level 10% of energy at each level is available to organisms at next higher level Biomass Because only 10% of energy at a given trophic level is available to next higher level, food chains are short; number of organisms is lower than previous level Levels Need to determine which organisms on are the correct and appropriate level

Practice Question 1 How does the flow of energy through an ecosystem conform to the laws of thermodynamics? Be sure to discuss its origination, transformation, and utilization.

Answer 1 Ecosystems conform to the laws of thermodynamics. The first law of thermodynamics states that energy is conserved; that is, energy cannot be created or destroyed, but it may be converted from one form to another. An ecosystem is a closed system that receives energy from outside sources. The organisms making up the ecosystem transform this energy into useful forms for storage and later utilization. The second law of thermodynamics states that some energy is lost as “useless” energy. Therefore, energy enters the system; is converted to food, which is stored by organism; energy is used by metabolic processes and energy is dissipated to atmosphere

Question 2 Green plants produce most of the oxygen in our atmosphere through a series of complex reactions. Name and describe this generalized reaction.

Answer 2 Green plants produce most of the oxygen in our atmosphere by photosynthesis. The generalized reaction for this process is often referred to as “the light reaction.” 6CO2 + 6H2O ------ C6H12O6 + 6O2

Question 3 What is the role of ATP and NADPH in metabolism? What effect does the amount of light have on the metabolism of green plants?

Answer 3 Green plants can make food by producing ATP (a carrier for energy) and HADPH (a carrier for electrons used in the synthesis of glucose) in their chloroplasts, which then reduce carbon dioxide and water to form a carbohydrate only in the presence of sunlight and chlorophyll

Question 4 ID the structure below and be specific. What factors limit the steepness of the sides of this structure?

Answer 4 The diagram shown may be biomass, energy, or numbers pyramid by trophic level. As one moves higher on pyramid, there is a decrease in biomass, energy, or numbers.

Question 5 A temperate deciduous forest contains the following organisms: oak tree, pine tree, grass, mouse, rabbit, cow, hawk, mushroom, dandelion, beetle, snake. Construct a food web using at least five of these organisms.