Introduction to Biology: Classification, Scientific Method, and Evolution

Classification of Life and Taxonomy

The 7 Properties of Life

Living organisms share several fundamental properties that distinguish them from non-living matter. These properties are essential for defining life:

• Order: Living things exhibit complex but ordered organization.

• Regulation: Organisms can regulate their internal environment to maintain homeostasis.

• Growth and Development: Information carried by genes controls the pattern of growth and development.

• Energy Processing: Organisms obtain and use energy to power their activities.

• Response to Environment: Living things respond to environmental stimuli.

• Reproduction: Organisms reproduce their own kind.

• Evolutionary Adaptation: Populations evolve over generations as individuals with traits best suited to their environment have greater reproductive success.

Levels of Biological Organization

Biological systems are organized into a hierarchy of structural levels, each building on the levels below it. Examples are provided for each level:

• Biosphere: All environments on Earth that support life (e.g., Earth).

• Ecosystem: All living and nonliving components in a particular area (e.g., a forest).

• Community: All organisms in an ecosystem (e.g., all plants, animals, and microbes in a pond).

• Population: All individuals of a species in a specific area (e.g., a flock of geese).

• Organism: An individual living thing (e.g., a single goose).

• Organ System: Several organs working together (e.g., digestive system).

• Organ: A structure composed of tissues (e.g., heart).

• Tissue: A group of similar cells performing a specific function (e.g., muscle tissue).

• Cell: The basic unit of life (e.g., muscle cell).

• Organelle: Functional components within cells (e.g., mitochondrion).

• Molecule: Chemical structure consisting of two or more atoms (e.g., DNA).

Emergent Properties

Emergent properties are new characteristics that arise at each level of biological organization, due to the arrangement and interactions of parts as complexity increases. For example, a functioning organ system can perform functions that individual organs cannot.

Domains and Kingdoms of Life

Life is classified into three domains and four major kingdoms:

• Domain Bacteria: Prokaryotic, unicellular organisms.

• Domain Archaea: Prokaryotic, often found in extreme environments.

• Domain Eukarya: Eukaryotic organisms, divided into four kingdoms:

  • Kingdom Protista

  • Kingdom Plantae

  • Kingdom Fungi

  • Kingdom Animalia

Scientific Method

Steps of the Scientific Method

The scientific method is a systematic approach to inquiry that involves the following steps:

• Observation: Gathering information about phenomena.

• Question: Formulating a question based on observations.

• Hypothesis: Proposing a tentative explanation or prediction.

• Experiment: Testing the hypothesis through controlled experiments.

• Results and Conclusions: Analyzing data and drawing conclusions.

• Falsifiability: The hypothesis must be testable and capable of being proven false.

Major Themes of Biology

• Unifying Theme: Evolution is the central theme that unifies all of biology, explaining both the unity and diversity of life.

Evolution and Natural Selection

Natural Selection

Natural selection is the process by which organisms with advantageous traits survive and reproduce more successfully, leading to the accumulation of beneficial adaptations in a population over generations.

Evolution by Natural Selection

Key observations and inferences that led Darwin to his theory:

• Variation exists within populations.

• More offspring are produced than can survive.

• Individuals with advantageous traits are more likely to survive and reproduce (differential reproductive success).

• Beneficial traits become more common in the population over time (adaptation).

Adaptations

Adaptations are inherited characteristics that enhance an organism's ability to survive and reproduce in specific environments. For example, bats have developed echolocation to navigate and hunt in the dark.

Artificial Selection

Artificial selection is the process by which humans selectively breed organisms for desired traits, such as dog breeds or crop varieties.

Phylogenetic Trees

Phylogenetic trees are diagrams that depict evolutionary relationships among species, showing patterns of descent from common ancestors. The most recent common ancestor is identified at branching points.

Types of Mimicry

• Batesian Mimicry: A harmless species mimics a harmful one.

• Müllerian Mimicry: Two or more harmful species resemble each other.

Practice Essay Questions

1. List and explain each of the levels of biological organization. Please use a specific organism as an example.

2. Explain the steps of the scientific method and apply the scientific method to an everyday life example.

3. A predatory bird is an environmental factor that a beetle population is exposed to. Explain what happens in a beetle population that originally consists of light, medium, and dark colored beetles when their environment is polluted with black soot. In your answer, please make sure to correctly incorporate the following terms: natural selection, reproductive success, individual variations, and evolution.

Additional info: Where the original notes were incomplete, standard textbook definitions and examples were provided for clarity and completeness.