1. E. Endorphins 2. B. Water (Friday Special) 3. B. Nitric oxide (NO) 4. B. Tuberous sclerosis 5. A. Pleiotropy 6. D. Malaria 7. C. Carbon dioxide levels in the blood rise to high levels 8. B. A multiple allele system 9. C. Reduced exposure to sunlight by small children (Friday Special) 10. C. Inbreeding depression 11. B. Oligodendrocytes (Friday Special) 12. C. Modifier genes affect the expression of the tongue-rolling allele 13. A. Release drugs 14. D. Homogametic 15. C. Angioplasty 16. C. Activation of genes 17. C. Females are ornamented, males are choosy, and males carry eggs in a brood pouch until hatching 18. B. Melatonin 19. E. Creating faceless avatars of actual male dancers which females then rated 20. D. Ectothermic homeotherms 21. A. Formaldehyde 22. A. Serotonin 23. E. Antiseptic environments that alter the immune system (Friday Special) 24. B. Ammonia 25. E. Dopamine 26. B. Urea 27. B. Diabetes (Friday Special) 28. B. 100% or E. 50% 29. D. Two recessive color blindness alleles on the X chromosomes 30. D. Crossing over of the SRY gene (Friday Special) 31. A. True 32. B. Atrioventricular valves 33. D. LDL's 34. C. 1 in 2 35. A. Kidney stones 36. E. Anterior pituitary 37. C. Water conservation 38. A. Acetylcholine 39. D. Variable environments 40. A. The production of germ cells with half the number of chromosomes found in the parental cells 41. C. Hypothalamus 42. C. The placebo effect (Friday Special) 43. B. Intermediate relatedness (third cousins) resulted in the highest reproductive success 44. A. Pheromone 45. B. The coefficient of inbreeding 46. E. Releasing hormones 47. B. Recessive alleles 48. C. Helicobacter pylori 49. C. Surfactant (Friday Special) 50. A. Prostaglandins