Biology Notes

Concepts of Biology

Introduction to Biology

• Biology is the science that studies life.
• Key question: What exactly is life?
• Biologists define life with a set of characteristics that all living things share.

Viruses

• Viruses can cause diseases by attacking host organisms.
• Characteristics of Viruses:
• Can reproduce only inside a living organism.
• Are not made of cells.
• Cannot replicate independently.
• Debate: Are viruses considered living? Why or why not?

Properties of Life

Living things exhibit the following characteristics:

1. Order: Complexity and structured organization.

• Example: A toad is organized into cells, tissues, and organ systems.

1. Sensitivity/Response to Stimuli: Interact and respond to the environment.

• Example: The sensitive plant (Mimosa pudica) reacts to touch.

1. Reproduction: Ability to reproduce to ensure species survival.

• Example: Kittens inherit traits from parents but vary in appearance.

1. Adaptation: Survive and thrive based on environmental changes.
2. Growth and Development: Organisms undergo physical changes throughout their life.
3. Regulation: Maintain internal organization and coordination of functions.
4. Homeostasis: Ability to maintain a stable internal environment.

• Example: Polar bears regulate body temperature despite cold climates.

1. Energy Processing: Metabolize energy to perform biological functions.

• Example: California condors utilize chemical energy for flight.

Levels of Organization of Living Things

• Atoms: The fundamental unit of matter.
• Molecules: Groups of two or more atoms.
• Macromolecules: Large compounds formed by combining smaller molecules.
• Organelles: Structures within cells performing specialized functions.
• Cells: Basic unit of life, all living things are made of cells.
• Tissues: Groups of similar cells performing a common function.
• Organs: Collections of tissues functioning together.
• Organ Systems: Groups of related organs.
• Organisms: Individual living entities.
• Population: A group of the same species in a specific area.
• Community: Groups of populations within a certain area.
• Ecosystem: Interactions between communities and their environment (biotic and abiotic).
• Biosphere: Sum of all ecosystems, the global zone of life.

The Diversity of Life

• Evolution: The gradual change allowing for the emergence of new species.
• Evolution is responsible for the diversity of life on Earth.

Hierarchical Taxonomy

• Approximately 8.7 million living things have been classified.
• Taxonomy organizes organisms into hierarchical categories from general to specific.
• Proposed by: Carl Linnaeus in the 18th century.

Taxonomic Hierarchy Example (Human)

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Primate
• Family: Hominidae
• Genus: Homo
• Species: sapient

Binomial Naming System

• Organisms are named using a two-part (genus and species) format.
• Example: Cyanocitta cristata for the North American blue jay.
• Genus name is capitalized; species name is lowercase.
• Names are italicized in print.

Phylogenetic Tree

• A diagram showing evolutionary relationships based on genetic and physical traits.
• Carl Woese's work led to the classification of life into three domains: Bacteria, Archaea, and Eukarya.

Branches of Biological Study

• Various fields include:
• Molecular Biology: Biological processes at the molecular level.
• Microbiology: Study of microorganisms.
• Neurobiology: Biology of the nervous system.
• Paleontology: Study of life's history through fossils.
• Zoology: Study of animals and plants.
• Specializations include ecologists, biotechnologists, and physiologists.

The Process of Science

• Biology discovers knowledge through a collaborative research community.
• Scientific Method: Steps including observation, hypothesis formulation, experimentation, data collection, and conclusion.
• Hypothesis: Testable explanations.
• Scientific Theory: Well-tested explanation for a set of observations.
• Scientific Laws: Describe natural phenomena mathematically.

Scientific Inquiry

• Logical thinking methods:
• Inductive Reasoning: General conclusions based on observations.
• Deductive Reasoning: Specific predictions based on general principles.
• Descriptive Science: Observational research.
• Hypothesis-Based Science: Testing specific questions through experiments.

Basic and Applied Science

• Basic Science: Expands knowledge without immediate application.
• Applied Science: Solves real-world problems.
• Basic science is foundational to applied sciences.

Reporting Scientific Work

• Peer-reviewed articles provide reliable scientific results.
• Results published without peer review are questionable.

Conclusion

• Understanding biology is essential for grasping life processes and scientific inquiry.
• Comprehensive study of life ranges from molecules to ecosystems, highlighting the diversity and interconnectedness of living organisms.