Cellular Respiration

2. solar energy arrives on Earth as electromagnetic radiation that is both invisible (I.e. UV, radio) and visible (light) • about 70% of insolation (incoming solar radiation) is absorbed by the hydrosphere and lithosphere, where it is converted to thermal energy (heat) which warms the atmosphere, evaporates water, and produces wind • about 30% is reflected directly back into space

4. virtually all the chemical energy stored in ecosystems was once light energy captured in the process of photosynthesis • low-energy, inorganic compounds (H2O and CO2) are converted into a high-energy, organic compound (glucose), releasing O2 as a “waste” product • chemical energy is stored in the roots, stems, leaves, and seeds of plants as carbohydrates and lipids • some energy is used to make building materials like proteins or information molecules like ATP • diatoms are the most important producers on Earth

5. Cellular Respiration • of the energy consumed as food by a consumer, 1/6 is converted to growth (proteins, etc.), 1/2 is not assimilated and lost as feces • the remaining 2/3 is used to make stored energy (carbohydrates, lipids) available to do work in the process of cellular respiration

6. producers and consumers transfer the energy stored in glucose to ATP molecules in the presence using oxygen, in mitochondria • cellular respiration is considered complementary to photosynthesis as the products (H2O and CO2) are the reactants in that process • no other chemical equations better illustrates our dependence on functioning ecosystems • there would be no food or oxygen to perform cellular respiration if not for producers • CYL: P. 41 #1,5,6,8,12

7. 2.5 - Food Webs and Ecological Pyramids • species can share the same habitat but the way they interact with other species and their environment is unique and defined as their ecological niche • What is the ecological niche of a black bear (P. 42)? • trophic (feeding) levels describe the position of an organism as energy flows through an ecosystem

8. food chains are very simplistic descriptions of feeding relationships and do not exist in nature • food webs are still incomplete but recognize that all organisms have more than food source and are a food source to many other organisms • the stability of ecosystems is a function of the complexity of food webs • although food webs have limited value in describing complex systems, they can be useful in modeling the effect of removing or adding a species to an ecosystem • Food Web Activity

9. Ecological Pyramids • a way to better quantify relationships in ecosystems is to construct pyramids • populations occupying different trophic levels vary in numbers, biomass, and energy • pyramids of numbers are not always pyramid-shaped • pyramids of biomass are always pyramid-shaped but do not always reflect the quality of the food at each trophic level

10. energy pyramids illustrates energy loss and transfer between trophic levels • the size of each layer represents the amount of energy available at that trophic level • energy is lost between trophic levels as heat, leaving only about 10% available to the next level • species at the highest trophic levels (top carnivores) have the least amount of energy available to them, resulting in fewer numbers and larger territories

11. Copy the energy pyramid and place appropriate species at each level. Show how energy is lost and explain why top carnivores require large territories. Humans can obtain more energy by consuming producers (i.e. vegetables) than other consumers (i.e. meat) Is vegetarianism the solution to feeding the world’s population? CYL: P. 47 #1,4,8