| O O O O O | letter |
| O2 reduction | chapter 9 | bio 113 | heading |
| Observational learning | chapter 51 | bio 114 | heading |
| Oil | chapter 5 | bio 113 | heading |
| Okazaki fragments | chapter 16 | bio 113 | heading |
| Oligochaeta, class | chapter 33 | bio 114 | heading |
| Oligosaccharides | chapter 8 | bio 113 | heading |
| One gene-one polypeptide hypothesis | chapter 17 | bio 113 | heading |
| Oogamy | chapter 28 | bio 114 | heading |
| Oomycota | chapter 28 | bio 114 | heading |
| Open circulatory system | chapter 33 | bio 114 | heading |
| Operant conditioning | chapter 51 | bio 114 | heading |
| Operator | chapter 18 | bio 113 | heading |
| Operon | chapter 18 | bio 113 | heading |
| Operon model | chapter 18 | bio 113 | heading |
| Operon, corepressed | chapter 18 | bio 113 | heading |
| Operon, inducible | chapter 18 | bio 113 | heading |
| Operon, lac | chapter 18 | bio 113 | heading |
| Operon, trp | chapter 18 | bio 113 | heading |
| Optimal foraging | chapter 51 | bio 114 | heading |
| Order, biological, hierarch of | chapter 2 | bio 113 | heading |
| Organelle | chapter 7 | bio 113 | heading |
| Organic compound, oxidation of | chapter 9 | bio 113 | heading |
| Organic final electron acceptor | chapter 9 | bio 113 | heading |
| Organismal ecology | chapter 50 | bio 114 | heading |
| Organisms are energy transducers | chapter 6 | bio 113 | heading |
| Organisms, model | chapter 21 | bio 113 | heading |
| Organisms, model, for the study of development | chapter 21 | bio 113 | heading |
| Organization and Control of Eukaryotic Genomes, The | chapter 19 | bio 113 | chapter title |
| Orientation | chapter 51 | bio 114 | heading |
| Origin of eukaryotes | chapter 28 | bio 114 | heading |
| Origin of life, The | chapter 26 | bio 114 | heading |
| Origin of self replication, scenario for | chapter 26 | bio 114 | heading |
| Origin of species (C. Darwin) | chapter 22 | bio 114 | heading |
| Origin of Species, The | chapter 24 | bio 114 | chapter title |
| Origin, prokaryotic | chapter 26 | bio 114 | heading |
| Origins of Eukaryotic Diversity, The | chapter 28 | bio 114 | chapter title |
| Origins of Metabolic Diversity, Prokaryotes and the | chapter 27 | bio 114 | chapter title |
| Origins of replication | chapter 16 | bio 113 | heading |
| Osmosis | chapter 8 | bio 113 | heading |
| Osteichthyes, class | chapter 34 | bio 114 | heading |
| Overview | chapter 29 | bio 114 | heading |
| Oxidation | chapter 9 | bio 113 | heading |
| Oxidation of carbon | chapter 9 | bio 113 | heading |
| Oxidation of glucose (complete) | chapter 9 | bio 113 | heading |
| Oxidation of organic compounds | chapter 9 | bio 113 | heading |
| Oxidation of pyruvate | chapter 9 | bio 113 | heading |
| Oxidation of water (photosynthesis) | chapter 10 | bio 113 | heading |
| Oxidation-reduction reactions | chapter 9 | bio 113 | heading |
| Oxidative phosphorylation (1) | chapter 9 | bio 113 | heading |
| Oxidative phosphorylation (2) | chapter 9 | bio 113 | heading |
| Oxidized carbon | chapter 4 | bio 113 | heading |
| Oxidized FADH2 | chapter 9 | bio 113 | heading |
| Oxidized NADH | chapter 9 | bio 113 | heading |
| Oxidizing agent | chapter 9 | bio 113 | heading |
| Oxygen requirements | chapter 27 | bio 114 | heading |