Overview
This lecture introduces fundamental concepts in biology, including the properties of life, the scientific method, biological organization, key themes, the role of evolution, and basic chemistry relevant to life.
The Science of Biology
- Biology studies the structures and functions of living organisms.
- Life is defined by order, evolutionary adaptation, regulation (homeostasis), reproduction, response to the environment, growth/development, and energy processing.
- Biology research can be descriptive (observation, recording, classification) or investigative (hypothesis-driven experimentation).
The Scientific Method
- Inductive reasoning develops general ideas from observations; deductive reasoning tests hypotheses using predictions.
- The scientific method involves observation, question, hypothesis formation, prediction, experimentation, and result analysis.
- Scientific theories synthesize extensive data and are broader in scope than hypotheses.
Biological Organization
- Life is organized in a hierarchy: atoms → molecules → organelles → cells → tissues → organs → organisms → populations → communities → ecosystems → biosphere.
- Structure determines function at every level.
- DNA carries genetic information; energy flows through producers (make food) and consumers (eat food).
Themes and Evolution
- Major biological themes: emergence of new properties, structure/function relationships, genetic information flow, energy/matter transformation, and evolutionary connections.
- Evolution is the core theme and explains adaptation and diversity.
Biodiversity & Taxonomy
- Biodiversity is categorized as ecosystems, communities, populations, and individual organisms.
- Taxonomy classifies organisms into named groups (genus and species).
- Only about 25 elements are essential for life.
Basic Chemistry for Biology
- Atoms are the smallest units of matter; molecules are groups of atoms bonded together.
- Ionic bonds involve electron transfer; covalent bonds involve electron sharing; hydrogen bonds are weak attractions between polar molecules.
- Isotopes have the same number of protons but different neutrons; some are radioactive and used in medicine and dating fossils.
Acids, Bases, and pH
- Acids donate H+ ions; bases accept H+ or produce OH− ions.
- pH measures acidity, with <7 acidic, >7 basic, and 7 neutral.
- Buffers help maintain stable pH in organisms.
- Salts form from reactions between acids and bases and help maintain fluid balance.
Water and Life
- Water is a polar molecule, excellent at dissolving substances, and vital for life.
- Properties include cohesion (water sticks to itself), adhesion (water sticks to other surfaces), high specific heat, and high heat of vaporization.
- Ice floats because its hydrogen bonds form a lattice that spaces molecules further apart than in liquid water.
Key Terms & Definitions
- Homeostasis — Maintaining internal balance.
- Hypothesis — A testable scientific explanation.
- Scientific Theory — Broad explanation supported by evidence.
- Taxonomy — Science of classifying organisms.
- Isotopes — Same element, different neutrons.
- Buffer — Substance that resists pH change.
- Cohesion — Attraction between water molecules.
- Adhesion — Attraction between water and other substances.
- pH — Scale of acidity/alkalinity.
Action Items / Next Steps
- Review textbook sections on properties of life and the scientific method.
- Complete any homework on defining key terms and practicing the scientific method steps.