College Biology: Themes and Concepts of Biology

Biology is the study of life, from microscopic cells to whole ecosystems.
Science is knowledge covering general truths, acquired and tested by the scientific method.

Scientific Method: A research method with defined steps including experiments and careful observation.
- Hypothesis: A testable, suggested explanation for an event.
- Theory: A tested and confirmed explanation for observations, generally accepted as fact, but not 'provable' (e.g., Evolution).

Fields related to the physical world, its phenomena, and processes (e.g., astronomy, biology, chemistry).
Can be broadly divided into:
- Life Sciences: Study living things (e.g., biology).
- Physical Sciences: Study nonliving matter (e.g., astronomy, geology, physics, chemistry).
Some fields are interdisciplinary (e.g., biophysics, biochemistry).
Often referred to as "hard science" due to reliance on quantitative data.

Inductive Reasoning: Uses specific observations/data (qualitative or quantitative) to form a general conclusion. Common in descriptive science.
Deductive Reasoning: Uses a general principle/law to predict specific results. Common in hypothesis-based science.
Descriptive (Discovery) Science: Usually inductive; aims to observe, explore, and discover.
Hypothesis-Based Science: Usually deductive; starts with a specific question/problem and a testable solution.

Observation: Identify well-defined, measurable, controllable phenomena.
Formulate Questions: Rephrase observations into specific questions.
Formulate Hypothesis: Provide a tentative, testable, and falsifiable explanation as a statement.
Make Predictions: Restructure the hypothesis as an "if-then" statement.
- Independent Variable: Manipulated by the researcher.
- Dependent Variable: Measured/recorded outcome.
Design Experiment: Create a controlled experiment.
- Controlled Experiment: Compares experimental and control groups to isolate the effect of the independent variable.
- Experimental Group: Receives the independent variable.
- Control Group: Does not receive the independent variable (placebo).
- Controlled Variables: Factors kept constant across groups to avoid influencing the outcome.
- Confounding Variables: Uncontrolled factors that may affect the outcome.
- Good design is feasible, repeatable, includes a control group, and is statistically viable.
Collect Data: Gather observations and measurements.
Interpret Data: Analyze the collected information.
Draw Conclusions: State whether the data supports or rejects the hypothesis.

Science does not claim to "prove" anything; scientific understandings are always subject to modification.
Falsifiability distinguishes science from non-science.

Scientists share findings through meetings or peer-reviewed manuscripts in scientific journals.
- Peer-review: Evaluation by qualified colleagues to ensure suitability for publication.
Scientific writing is brief, concise, accurate, and detailed enough for reproducibility.
Typical sections: Abstract, Introduction, Materials and Methods, Results, Discussion, Conclusion, Acknowledgments, References.

All living organisms share these characteristics:

Order: Highly organized, coordinated structures (cells, tissues, organs).
Sensitivity or Response to the Environment: React to diverse stimuli (e.g., light, touch).
Reproduction: Pass DNA/genes to offspring.
Adaptation/Evolution: Characteristics change over time via natural selection and mutations, leading to fitness for the environment.
Growth and Development: Genes direct cellular growth and development.
Regulation/Homeostasis: Maintain stable internal conditions despite environmental changes.
Energy Processing: Utilize energy for metabolic activities (e.g., from sun or food).

Life is organized hierarchically from smallest to largest:

Atom: Smallest fundamental unit of matter.
Molecule: Two or more atoms held by chemical bonds.
Macromolecule: Large molecules formed by polymerization.
Organelle: Subunits within eukaryotic cells surrounded by membranes.
Cell: Smallest fundamental unit of living organisms.
- Prokaryotic: Single-celled, no membrane-bound nucleus (e.g., bacteria).
- Eukaryotic: Contain membrane-bound organelles and nucleus.
Tissue: Groups of similar cells performing related functions.
Organ: Collections of tissues performing a common function.
Organ System: Functionally related organs.
Organism: Individual living entity.
Population: All individuals of a species in a specific area.
Community: Sum of populations in a particular area (all living things).
Ecosystem: All living things in an area plus abiotic (nonliving) parts.
Biome: Compilation of ecosystems.
Biosphere: Collection of all ecosystems; zones of life on Earth.

Evolution: The process of gradual change in populations/species over time, creating life's diversity.
Phylogenetic Tree: Summarizes the evolutionary relationships of life forms (e.g., three domains: Bacteria, Archaea, Eukarya).
Branches of Biology (Subdisciplines):
- Molecular biology & biochemistry: Study processes at molecular/chemical level.
- Microbiology: Study microorganisms.
- Neurobiology: Study the nervous system (interdisciplinary neuroscience).
- Paleontology: Study life history using fossils.
- Zoology: Study of animals.
- Botany: Study of plants.
- Other specializations: biotechnology, ecology, physiology, etc.