O (Oxygen atom) O Antigens O2 (Molecular Oxygen) O2 (Oxygen Molecule) O3 (Ozone) OAA (Oxaloacetic Acid) Oat Coleoptile Test Obesity Obesity Obesity Drugs (Weight-Loss Drugs) Obesity Drugs (2) Obesity Drugs Types Objective (s) Objective Response Objective vs. Subjective Objectivity (in Science) Objectivity Challenges (in Science) Obligate Obligate Aerobe Obligate Anaerobe Obligate Anaerobes Obligate Parasite Obligate Saprophyte OBP (Odorant Binding Protein) Obscurin Observation Analysis oC (Celsius Degee) Occam’s (Ockham’s) Razor Occipital Lobe Occlude Occluding Junction Occult Occupancy Occupational Toxicology Ocean Energy Ocean Iron Fertilization (OIF) Ocean Twilight Zone Oceanic Island Oceanic Subduction Oceanography Oceanography Ocellus Ochratoxin Ochre Codon OCT (Ornithine Carbamoyltransferase or Ornithine Carbamyl Transferase) Octamer Octet Rule Octopine Plasmids Octoploid Octoploidy Ocular OD (Optical Density ) Odontoceti Odontogenesis Odontogenic Tissue Odorant Binding Protein Oedema (Edema) Oesteoporosis Oestradiol Oestriol Oestrogen (Estrogen) Oestrogen Receptor-Positive Breast Cancer Oestrone (Estrone) Oestrous Cycle (Estris Cycle) Oestrus (Estrus) Off Shelf Off Target Effects Offspring O-GlcNAc Transferase Ogston Hypothesis Ohm Ohm ( Ω ) Ohm's Law Ohmic Electron Contact Oil of Juniper Oil Shale Oilg-, Oligo- Oil-immersion Objective Oils Oils, Essential Oils, Fixed Okadaic Acid Okadaic Acid Okadaic Acid (2) Okazaki Fragment Okazaki Fragment Oleande Oleandrin Oleandrin Oleanolic Acid Olefin (Alkene) Olefin (Alkene) Oleic Acid Olfaction Olfaction (Smell) Olfactology (Study of Smell) Olfactory Lobes Olfactory Organ Oligo- Oligo- Oligo- Oligo- (Short) Oligo A Tail Oligo Synthesis Oligo Synthesis (Oligonucleotide Synthesis) Oligocene Oligocytosis (Anemia) Oligodendrocyte Oligodendrocytes Oligodendrocytes Oligodynamic Effect Oligogene Oligogenesis Oligogenic Oligogenic Trait Oligogenics Oligomer Oligomeric Enzymes Oligomeric Plasmid Oligomeric Protein Oligomeric Protein Oligomerization Oligomycin Oligomycins Oligonucleotide Oligonucleotide Synthesizer Oligopeptide Oligopeptide-Binding Protein Oligopotent Oligopotential Oligoribonucleotide Oligosaccharide Oligosaccharides Oligospermia Oligosynaptic Oligotrophic Olivine Basalt OLs )Oligodendrocyte) Omar Khayyam (1048–1131) Omar Khayyam (c. 1048-1131) Scientist) Omasum (pl. Omasa) Omega Omega Fatty Acids Omega Fatty Acids (2) Omega Oxidation Omega-3 Fatty Acid Omega-3 Fatty Acids Omega-3 Fatty Acids (2) Omega-3 Triglycerides Omega-6 Fatty Acid Omega-6 Fatty Acids Omega-9 Fatty Acids Omega-Oxidation Omics omics Omics Datasets Omics Research Omics Research (2) Ommatidium Ommochromes Omni-, Omnis- Omnivore (Omnivorous ) Omp (Orotidine 5'-Monophosphate) Oncofetal Oncogene Oncogene Oncogene Addiction Oncogene Amplification Oncogene Hypothesis Oncogene Hypothesis Oncogene Junction- Oncogene, Proto- Oncogene, Viral- Oncogenes Oncogenes (2) Oncogenes (2) Oncogenesis Oncogenetics Oncogenic Oncogenic DNA Viruses Oncogenic Viruses Oncogenomics Oncologic (Oncological) Oncological (Oncologic) Oncologist Oncology Oncolytic Oncolytic Virus Oncoma (Neoplasm) Oncometabolite OncoMiR Oncoprotein Oncornavirus Oncosome (pl. Oncosomes) Oncovirus One Carbon Pool One Electron Carrier One Gene One Enzyme Hypothesis One Gene One Polypeptide Hypothesis One Gene One Protein Hypothesis One-Shot Learning ONPG Onse (Onsite Energy Corporation) Onset ONTD (Open Neural Tube Defect) Ontogeny Ontology (Information) Oocyte Oocyte (Ovocyte) Oogamous Oogenesis (Ovogenesis) Oogonium (Egg mother) Oolemma (Zona pellucida) Oonotic Bacterial Diseases Ooryzavirus Opal Codon Opaque Open Circulatory System Open Complex Open Loop System Open Ocean Open Science Open Source Open System OpenAI Open-Field Test Operable Operation Operational Taxonomic Unit Operator Operator Gene Operon Operon Theory Ophthalmothermometer Opiate Opiates Opiates (Opioids) Opine Opines Opioid Opioid Analogs Opioid Receptor    Opioids Opioids (2) Opium Opium Opium Opp (Oligopeptide Binding Protein) Opportunistic Opportunistic Pathogen Opsin Opsins Opsonin Opsonization Opsonize Optic Nerve Optical Aberration Optical Dating Optical Isomerism Optical Isomers Optical Mapping Optical Mapping Optical Omnivorousness Optical Rotation Optical Telescope Optical Test Optically Stimulated Luminescence Optimize Optimum Optimum pH Optofluidics Optogenetic Manipulation Optogenetics OPV Oral Oral Antibiotic Oral Cavity Oral Contraceptives Orane G Orbit Orbital Period ORC (Origin Recognition Complex) Orcein Orchis (Testicle) Orcinol Order Order of Magnitude Ordinal Ordinate Ordovician Period ORF (Open Reading Frame) ORFs (Open Reading Frames) Organ Organ Culture Organ Donor Organ Microchips Organ of Corti Organ Transplant Organ Transplant Organelle Organic Organic Acid Organic Brain Syndrome Organic Chemistry Organic Compound Organic Evolution Organic Fertilizers Organic Foods Organic Hydroperoxide Organic Hydroperoxide Resistance Protein Organic Matter Organic Rankine Cycle (ORC) Organic Solvent Organism Organism(s) Organization Organizer Organo- Organochlorine Compounds Organochlorine Insecticide Poisoning Organogenesis Organoid Organoid (2) Organoids Organoids Applications Organoids Formations Organoids Structure Organometallic Chemistry Organometallic Compounds Organometallic Compounds Organometallic Compounds Organophosphate Organophosphate Insecticide Poisoning Organophosphate Poisoning Organophosphorus Compounds Organotroph Organotypic Organotypic Cultures Origin Origin of Life Origin of Replication Origin of Species Original Equipment Originality Orn (L-Ornithine) Ornithine Ornithine Carbamoyltransferase Ornithine Cycle (Urea Cycle) Ornithine Decarboxylase Ornithine Decarboxylase (ODC) Ornithine/Citrulline Cycle Ornithology Ornithology (Study of Birds) Ornithophily Oropharynx Orphan Viruses Ortet Ortho- (Straight, Right, Upright, Correct) Ortho Phosphoric Acid (Phosphoric Acid) Orthobiosis Orthocytosis Orthodiagram Orthoester (RC(OR')(ORʺ)(OR‴) Orthogenesis Orthogenics (Eugenics) Ortholog Orthologous Orthologous Genes Orthologous Genes (Orthologs) Orthology Orthomolecular Orthomolecular Psychiatry Orthomolecular Therapy Orthomolecular Medicine Orthomyxoviruses Orthopedic Orthoptera Orthopteran Orthosteric Orthotopic Orthotopic Animal Models Os (Osmium) Element Osazone Osazone Test Osazones Oscillating Electronic Spin State Oscillation Osmic Acid Osmium (Os) Osmium Tetroxide Osmo Regulators Osmolarity Osmoregulation Osmosis Osmotic Potential (ψs) Osmotic Pressure (Π) Osmotic Regulation Oso Confomers Osp (Outer Surface Protein) Ossicles Osteichthyan Osteoblast Osteoblastic Osteocalcin Osteoclast Osteocytes Osteoid Osteology Osteology (2) Osteopathy Osteopenia Osteoporosis Osteoporosis Osteoporosis (2) Osteosarcoma Osteotropism Ostriches Oter Molecular Layer (External Plexiform Layer) Otolaryngology (Otorhinolaryngology; ENT) Otoliths Otology (Study of The Ear) Otto Heinrich Warburg (1883-1970) (Scientist) Ouabain Ounce (Oz) Outbreak Outbreak Outbreeding Outbreeding (Crossbreeding) Outcome Data Outcomes Outcomes Research Outcross Outer Membrane Outer Nuclear Membrane Outer Root Sheath Outlier Outlier in Statistics Outlier Values Output Outside-In Signalling Ova (sing. Ovum) Oval Window Ovalbumin (Egg Albumin) Ovarian Agenesis Ovarian Cancer Ovarian Cancer Ovariole (Egg Tubes) Ovarium Ovary (Ovarium) Over Dominance (Overdominance) Overall Survival Overdose Overexpression Overiectomy Overlap Microtubule Overlapping Overlapping Clones Overlapping DNA Overlapping Gene Overlapping Inversion Overton-Meyer Hypothesis Overturning Circulation Overview Overweight Overwiding Overwound Ovicide Ovicular OVID XBB.1.5 Subvariant Oviduct Ovigerm (Oogonium; Oocyte) Oviparity Oviparous Oviposition Ovipositor Ovocyte (Oocyte) Ovogenesis (Oogenesis) Ovoid Ovoviviparity Ovoviviparous Ovulation Ovulation Ovulation Inhibitors Ovule Ovum Ovum (Egg; pl. Ova) Oxalate (C2O2−4) Oxalates Oxalic Acid Oxalic Acid Oxaloacetic Acid Oxaloacetic Transaminase (Aspartate Aminotransferase) Oxic Zone Oxidant (Oxidizing Agent) Oxidase Oxidase Oxidases Oxidation Oxidation - Reduction Reactions (Redox Reactions) Oxidation Number (Oxidation State) Oxidation Reduction Potential (E) Oxidation Reduction Reaction Oxidation β- Oxidation-Reduction (Redox) Oxidation-Reduction Indicator Oxidation-Reduction Reaction Oxidation-Reduction Reactions Oxidation-Reduction Reactions (Redox Reactions) (2) Oxidative Oxidative Burst Oxidative Degradation Oxidative Metabolism Oxidative Phosphorylation Oxidative Phosphorylation Oxidative Phosphorylation Oxidative Phosphorylation (2) Oxidative Phosphorylation Inhibitors Oxidative Photorespiration Oxidative Stress Oxidative Stress Oxidative Stress (2) Oxide Ion (O--)  Oxidize Oxidizing Agent Oxidizing Agent (Oxidant) Oxidoreductase Enzyme Oxidoreductases (EC 1) Oxime Compound (RCH=NOH) Oximeter Oxisols Oxoglutarate (2-Oxoglutarate) Oxoglutarate Dehydrogenase Oxycodone OxyContin OxyContin Oxygen (O) Oxygen Burning Oxygen Carrier Proteins Oxygen Concentration Oxygen Consumption Oxygen Cycle Oxygen Debt Oxygen Dissociation Curve Oxygen Electrode Oxygen Electrode Oxygen Electronic Configuration Oxygen Industrial Sources Oxygen Isotopes Oxygen Metabolism Oxygen Molecule (O2) Oxygen Quotient (QO2) Oxygen-28 Oxygenases Oxygenate oxygenbolic Oxyhemoglobin (HbO2) Oxymyoglobin (MbO2) Oxytocin (alpha Hypophamine) Oz. (Ounce) Ozempic Ozempic Ozempic (Semaglutide) Ozempic (Semaglutide) Ozone Ozone (O3) Ozone Depletion Ozone Destruction Ozone Layer