1. A. Acetabulum of the femur 2. A. Archaea 3. C. Electrons 4. C. Haversian canals 5. C. Peer review 6. D. Sarcoplasmic reticulum 7. D. Products 8. C. Hydrogen 9. E. Arrival of human immigrants in Australia 10. A. Nervous 11. B. Low levels of Carbon-13 (Friday special) 12. C. Low endurance 13. A. Electrons 14. A. Wendell Johnson Stuttering Project 15. C. Potassium 40/Argon 40 16. D. Dysfunction of the autoimmune system 17. A. Blood clot formation 18. E. All of the above may apply, depending on the circumstances 19. D. Carbon-hydrogen bonds 20. D. The Yucatan Peninsula (Friday special) 21. C. Creatine phosphate 22. D. Cosmic rays 23. A. Gout 24. B. Rigor mortis 25. C. Oxygen 26. E. Theory 27. D. Social darwinism (Friday special) 28. C. Cholesterol 29. A. Relatively high (Friday special) 30. C. Ribosomes 31. C. Neutrons (Friday special) 32. E. Calcium 33. B. Osteoporosis 34. B. A natural resistance to obesity 35. B. 50,000 36. A. Shin splints 37. A. C4 metabolism (Friday special) 38. A. Sciatica 39. D. Glycogen 40. A. Producing ATP, high-energy compounds (NADPH), and oxygen 41. D. Hydrophobic interactions 42. C. Myostatin 43. B. Queen Victoria (Friday special) 44. E. Myoglobin 45. D. Intelligent design 46. E. Calcium 47. D. An enzyme 48. B. More persistent than testosterone 49. D. 4 50. B. Mitochondrial DNA