USABO2
Unit 1: The Chemistry of Life
Life is based on chemical principles, and understanding the molecules that make up organisms is essential.
1. The Chemical Context of Life
Atoms are the building blocks of matter, made of protons, neutrons, and electrons.
Chemical bonds (covalent, ionic, hydrogen, van der Waals) determine molecular interactions.
Water has unique properties (cohesion, adhesion, high heat capacity, solvent abilities) crucial for life.
2. Carbon and the Molecular Diversity of Life
Carbon forms the backbone of biological molecules.
Functional groups (hydroxyl, carboxyl, amino, phosphate) influence chemical properties.
Isomers are molecules with the same formula but different structures and functions.
3. The Structure and Function of Large Biological Molecules
Carbohydrates: Provide energy and structure (sugars, starch, cellulose).
Lipids: Hydrophobic molecules used for energy storage, insulation, and membranes (fats, phospholipids, steroids).
Proteins: Perform most cell functions (enzymes, transport, structure).
Nucleic Acids: Store genetic information (DNA, RNA).
Unit 2: The Cell
Cells are the basic unit of life, and their structure and function are critical for survival.
4. A Tour of the Cell
Prokaryotic cells (bacteria, archaea) lack nuclei and organelles, while eukaryotic cells (plants, animals) have them.
Organelles like mitochondria, the nucleus, and ribosomes perform specialized functions.
5. Membrane Transport and Cell Signaling
Cell membranes are semi-permeable, controlling what enters and exits.
Passive transport (diffusion, osmosis) doesn’t use energy, while active transport (pumps, endocytosis) does.
Cells communicate via chemical signals that bind to receptors and trigger responses.
6. An Introduction to Metabolism
Metabolism includes all chemical reactions in cells.
Enzymes speed up reactions by lowering activation energy.
ATP is the energy currency of the cell, used in reactions requiring energy.
Unit 3: Genetics
Genetics explains how traits are inherited and how cells use genetic information.
7. Cellular Respiration and Fermentation
Cells make ATP using glucose in three steps: glycolysis, Krebs cycle, oxidative phosphorylation.
Oxygen is required for aerobic respiration, while fermentation happens without oxygen.
8. Photosynthesis
Plants use sunlight to convert CO₂ and H₂O into glucose and oxygen.
The light reactions capture energy, and the Calvin cycle makes sugar.
9. The Cell Cycle
Cells grow and divide through mitosis (for growth and repair).
Checkpoints regulate cell division; cancer results when these fail.
10. Meiosis and Sexual Life Cycles
Meiosis produces gametes with half the chromosome number, introducing genetic variation.
Fertilization restores the full chromosome count.
11. Mendelian Genetics
Traits follow predictable inheritance patterns based on dominant and recessive alleles.
Punnett squares help predict offspring traits.
12. Chromosomal Basis of Inheritance
Genes are on chromosomes; crossing over increases variation.
Mistakes in chromosome number (nondisjunction) can cause disorders like Down syndrome.
13. Molecular Basis of Inheritance
DNA replication ensures genetic information is passed on.
Errors can lead to mutations, some of which cause diseases.
14. Gene Expression
DNA is transcribed into RNA, which is translated into proteins.
Gene regulation allows cells to turn genes on and off.
15. Biotechnology
Scientists use techniques like PCR, CRISPR, and cloning to study and modify DNA.
Unit 4: Mechanisms of Evolution
Evolution explains how life changes over time.
16. Darwinian Evolution
Natural selection favors traits that improve survival and reproduction.
Fossil evidence and comparative anatomy support evolution.
17. Population Genetics
Evolution happens when allele frequencies change in a population.
Mutations, genetic drift, and gene flow contribute to variation.
Unit 5: The Evolutionary History of Life
How life originated and diversified.
18. Phylogeny and the Tree of Life
Organisms are classified based on evolutionary relationships.
Phylogenetic trees show common ancestors and speciation events.
Unit 6: Plant Form and Function
Plants have specialized structures for growth, transport, and reproduction.
19. Plant Structure, Growth, and Development
Meristems allow plants to grow continuously.
Roots, stems, and leaves have different functions.
20. Resource Acquisition and Transport in Plants
Water moves through xylem via transpiration.
Sugars are transported in phloem from sources (leaves) to sinks (roots).
21. Reproduction and Development of Flowering Plants
Angiosperms reproduce via flowers, using pollen and ovules.
Seeds contain embryos that grow into new plants.
Unit 7: Animal Form and Function
Animals rely on specialized organ systems to maintain homeostasis.
22. Animal Structure and Function
Tissues (muscle, epithelial, connective, nervous) make up organs and systems.
Homeostasis keeps internal conditions stable.
23. Animal Nutrition
Digestive systems break down food for energy and nutrients.
Some animals have specialized diets and adaptations.
24. Circulation and Gas Exchange
The heart and blood vessels transport oxygen and nutrients.
The lungs or gills exchange oxygen and carbon dioxide.
25. The Immune System
The body defends against pathogens using innate and adaptive immunity.
Vaccines help develop immunity by training the immune system.
26. Hormones and the Endocrine System
Hormones control processes like growth and metabolism.
The endocrine system communicates via chemical messengers.
27. The Nervous System
Neurons transmit signals via electrical impulses.
The brain and spinal cord coordinate body functions.
28. Muscles and Movement
Skeletal, cardiac, and smooth muscle enable movement and organ function.
Muscles contract by sliding filaments (actin and myosin).
Unit 8: Ecology
Ecology studies how organisms interact with each other and their environment.
29. Ecosystems and the Biosphere
Biomes are large ecosystems with unique climates and species.
Energy flows through food chains, with producers at the base.
30. Population Ecology
Populations grow based on birth and death rates.
Carrying capacity limits growth due to resource availability.
31. Community Ecology
Species interact as predators, competitors, or mutualists.
Keystone species play a critical role in ecosystems.
32. Conservation Biology
Biodiversity is important for ecosystem stability.
Human activities impact climate and ecosystems, leading to conservation efforts