1.1 How Energy Enters the Biosphere

1. 1.1 How Energy Enters the Biosphere (pages 8 – 15)

2. The Earth is a closed system • Earth is both an open (with regards to energy) and closed (with regards to matter) system. • Energy enters the biosphere as sunlight and leaves as heat that is radiated back in to space, making Earth an open system with regards to energy.

3. No matter ever enters or leaves Earth, other than the occasional meteor and satellite, making Earth a closed system with respect to matter.

4. The Sun is the main source of energy • Scientists estimate that one to two percent of all the energy that reaches Earth from the Sun is captured by producers and converted to chemical energy through photosynthesis.

5. About half of the incoming energy is absorbed by the atmosphere or reflected back into space without ever reaching Earth’s surface.

6. Albedo: the amount of energy a surface reflects. • Light colored surfaces have a high albedo, dark surfaces have a low albedo

7. Answer the following questions • Question 1. Explain how a surface with a high albedo differs from a surface with a low albedo. • Question 2. If there was an increase in surfaces with a high albedo on Earth, how would Earth’s surface temperature be affected?

8. Question 3. In what forms does energy exist as it moves through the process of photosynthesis? • Question 4. Does all of the energy that initially enters into the process of photosynthesis get converted into usable energy?

9. Question 5. In what forms does energy exist as it moves through the process of cellular respiration? • Question 6. Does all of the energy that initially enters into the process of cellular respiration get converted into usable energy?

10. Photosynthesis • Energy from the Sun is captured by photosynthetic organisms (producers). • Producers use this energy to convert inorganic substances into glucose and other energy-rich compounds such as starches, proteins, and fats.

11. These compounds provide energy and matter for the producers themselves, as well as for consumers of the producers.

12. Question 7. What are the reactants in the process of photosynthesis? What are the products? • Question 8. Is the process of photosynthesis exothermic or endothermic?

13. Question 9. Write the word equation representing the process of photosynthesis. Include the word “energy” as a product or a reactant.

14. Cellular Respiration • All living organisms contain mitochondria, the organelle where the process of cellular respiration occurs.

15. Glucose created in the process of photosynthesis is used in the process of cellular respiration. • The process of cellular respiration converts the chemical energy stored in the glucose into useable energy in the form of ATP (adenosine triphosphate)

16. Question 10. What are the reactants in the process of cellular respiration? What are the products? • Question 11. Is the process of cellular respiration exothermic or endothermic?

17. Question 12. Write the word equation representing the process of cellular respiration. Include the word “energy” as a product or a reactant.

18. Comparing Photosynthesis and Cellular Respiration • Notice that photosynthesis and cellular respiration are almost the reverse of each other. Both processes use the same matter, but the form of energy used and released is different.

19. Question 13. In what way does the energy involved with photosynthesis differ from the energy involved with cellular respiration?

20. Question 14. Use the graphic organizer below to write down the similarities and differences between the processes of photosynthesis and cellular respiration. Write the similarities in the space where the two circles overlap.

21. Producers • Autotroph: “self-feeders”, organism that synthesizes its own food from inorganic molecules by using light or chemical energy (also known as producer).

22. The Sun is the source of energy for all producers that grow on Earth’s surface or that float on or near the surface of the ocean and other bodies of water. • Producers (green plants, algae, and some bacteria) are able to harvest 1-2% of available solar energy.

23. Autotrophs use the energy in sunlight to convert inorganic carbon dioxide and water into organic molecules that store chemical energy within their bonds. • This energy can then be passed further along a food chain.

24. Question 15. What percentage of the Sun’s energy is absorbed by Earth’s land and water surfaces? What happens to the rest of the solar energy?

25. Chemosynthesis • Chemosynthesis: process using the energy from chemical nutrients to convert inorganic carbon into organic carbohydrates (sugar and starch) in the absence of sunlight.

26. Entire ecosystems have been discovered at depths of 2500m in the oceans of the planet. The unusual deep-sea vent organisms live near scalding hot, acidic water that is heated by geothermal activity. • Light cannot penetrate water to these depths; the deep-sea organisms do not rely on the energy of the sun to support life.

27. Thermophile bacteria use chemical energy stored in hydrogen sulfide bonds to convert CO2 and H2O into C6H1206 (glucose) • Sulfuric acid is produced as a byproduct of this process

28. Question 16. What are the similarities and differences between the processes of photosynthesis and chemosynthesis?

29. Consumers • Only producers are able to capture energy from the Sun (or inorganic molecules). • All other organisms rely on producers to meet their energy needs. • Heterotroph (consumer): an organism that cannot synthesize its own food, and must derive its energy from organic molecules formed by producers.

30. Consumers can be classified into groups based on how they obtain their food.

32. Question 17. Why are decomposers heterotrophic organisms and not producer organisms?

33. The Fate of Energy in the Biosphere • Matter cycles within the biosphere, but energy passes through it.

34. As chemical energy is transferred from producers to consumers to decomposers, all the energy eventually dissipates into the environment as heat.

35. Question 18. Use figure 1.7 on page 14 to color code the figure to the right. Use a different color for matter and energy. What do you notice about the “cycling” of matter and energy in the biosphere? Does matter or energy exist as a closed system? How do you know?

36. The First and Second Laws of Thermodynamics • Energy flows as a one-way path through the biosphere • First Law of Thermodynamics: energy cannot be created nor destroyed. It can only be converted from one form to another or transferred from one object to another.

37. Second Law of Thermodynamics: no process of energy conversion is 100% efficient. (With each energy conversion or transfer there is less energy to do useful work).

38. Question 19. How do the first and second laws of thermodynamics explain the idea that few organisms may be supported as trophic levels increase? (ie. There are fewer secondary consumers than there are primary consumers)

39. Homework: Answer section 1.1 review questions (3-5,7) on page 15