Online Biology Tutorials
| Chemical Bond Formation |
The Evolution of the Three Domains |
| Synthesis of Prebiotic Molecules in an Experimental Atmosphere |
Food Vacuoles Handle Digestion and Excretion |
| Macromolecules |
Family Tree of Chloroplasts |
| Pasteur's Experiment |
Life Cycle of a Moss |
| The E.R. and Golgi Apparatus |
Life Cycle of a Conifer |
| Passive Transport |
Life Cycle of a Zygomycete |
| Active Transport |
Life Cycle of a Cnidarian |
| Receptor-Mediated Endocytosis |
Life Cycle of a Frog |
| Enzyme Catalysis |
Secondary Growth: The Vascular Cambium |
| Allosteric Regulation of Enzymes |
The Pressure Flow Model |
| Electron Transport and ATP Synthesis |
Nitorgen and Iron Deficiencies |
| Two Experiments Demonstrate the Chemiosmostic Mechanism |
Tropisms |
| The Source of Oxygen Produced by Photosynthesis |
Went's Experiment |
| Photophosphorylation |
Auxin Affects Cell Walls |
| Tracing the Pathway of CO2 |
Double Fertilization |
| Mitosis |
The Effect of Interrupted Days and Nights |
| Meiosis |
Signaling Between Plants and Pathogens |
| Independent Assortment of Alleles |
Control, REgulation, and Feedback |
| Alleles That Do Not Sort Independently |
Complete Metamorphosis |
| The Meselson-Stahl Experiment |
Hypothalamic-Pituitary-Endocrine Axis |
| DNA Replication, Part 1 |
Hormonal Regualtion of Calcium |
| DNA Replication, Part 2 |
Fertilization in the Sea Urchin |
| Thinkwell's DNA Replication |
The Ovarian and Uterine Cycles
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| Transcription |
The Resting Membrane Potential
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| Initiation of Transcription |
The Action Potential |
| Deciphering the Genetic Code |
Synaptic Transmission |
| Translation (Protein Synthesis) |
Sound Transduction in the Human Ear
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| The lac Operon |
Information Processing in the Retina
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| The tryp Operon |
Information Processing in the Spinal Cord |
| RNA Splicing |
Molecular Mechanisms of Muscle Contraction |
| Signal Transduction Pathway |
Smooth Muscle Action |
| Separating Fragments of DNA by Gel Electrophoresis |
Airflow in Birds |
| DNA Chip Technology |
Airflow in Mammals |
| DNA Testing by Allele-Specific Cleavage |
The Cardiac Cycle |
| Sequencing the Genome |
The Digestion and Absorption of Fats |
| Cells of the Immune System |
Insulin and Glucose Regulation |
| Pregnancy Test
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The Mammalian Kidney
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| Cellular Immune Response |
Hormonal Control of Sexual Behavior |
| Humoral Immune Response |
Circadian Rhythms |
| A B-Cell Builds an Antibody |
Time-Compensated Solar Compass |
| Embryonic Stem Cells |
The Costs of Defending a Territory |
| Early Asymmetry in the Embryo |
Foraging Behavior |
| Pattern Formation in the Drosophila Embryo |
Exponential Growth Simulation |
| Gastrulation |
Logistic Growth Simulation |
| Tissue Transplants Reveal the Process of Determination |
Predator-Prey Simulation |
| Modularity |
Habitat Fragmentation |
| Evolution of the Continents |
Primary Succession on a Glacial Moraine |
| Natural Selection |
Rain Shadow |
| The Hardy-Weinberg Equilibrium |
Biomes |
| Assessing the Costs of Adaptations |
Biogeography Simulation |
| Speciation Mechanisms |
The Global Hydrological Cycle |
| Founder Events Lead to Allopatric Speciation |
The Global Carbon Cycle |
| Reconstructing and Using Phylogenies |
The Ocean Conveyor Belt |
| Molecular and Genomic Evolution |
The Global Nitrogen Cycle |