Foundations of General Biology: Scientific Method, Characteristics of Life, and Cell Types

Terms to Know

Science and Inquiry

Science is an approach to understanding the natural world through observation and explanation. Inquiry is the scientific process that involves asking questions, forming hypotheses, and testing explanations, often focusing on specific problems.

• Science: Systematic study of the natural world using observation and experimentation.

• Inquiry: The process of seeking information and explanations, often through the scientific method.

Scientific Method

The scientific method is a logical, systematic approach to problem-solving in science. It involves several key steps:

• Observation: Gathering information about phenomena.

• Hypothesis: A testable explanation for an observation, often based on prior knowledge or inductive reasoning.

• Prediction: A specific statement about what will happen under certain conditions if the hypothesis is correct.

• Experiment: A controlled test designed to evaluate the effects of changing one factor at a time.

• Analysis: Interpreting data to determine if the hypothesis is supported.

• Conclusion: Summarizing findings and determining next steps.

Additional info: The scientific method is iterative; if a hypothesis is not supported, scientists revise or create new hypotheses and repeat the process.

Hypothesis vs. Theory

• Hypothesis: A testable statement that explains an observation and can be supported or refuted by experimentation.

• Theory: A broader explanation supported by a large body of evidence, integrating multiple hypotheses and observations. Theories require more evidence and time to reach consensus.

Example: The cell theory states that all living things are made of cells, supported by extensive evidence.

Evolution

Evolution is the process by which species change over time through modification. It explains the diversity of life and is supported by evidence from many scientific disciplines.

• Natural selection: Mechanism by which organisms better adapted to their environment tend to survive and reproduce.

• Speciation: Formation of new species through evolutionary processes.

Learning Goals

1. The Scientific Method and Inquiry

Understanding the scientific method is essential for scientific inquiry. It consists of observation, hypothesis formation, prediction, experimentation, and analysis.

• Testable hypotheses: Must be able to be supported or refuted by experiments.

• Controlled experiments: Only one variable is changed at a time to isolate effects.

• Scientific reasoning: Involves logical, testable explanations and evidence-based conclusions.

Additional info: Science does not address supernatural phenomena; only natural explanations are considered.

2. Hypotheses vs. Theories

A hypothesis is a specific, testable answer to a question, while a theory is a broader, well-supported explanation that integrates multiple hypotheses and evidence.

• Hypotheses: Lead to predictions and can be tested directly.

• Theories: Require more evidence and time to develop consensus.

Example: "All living things are made of cells" is a theory supported by many experiments.

3. Limitations of Science

Science is limited to studying the natural world and cannot address supernatural or religious phenomena. Scientific facts are based on evidence and reasoning, not belief.

• Natural phenomena: Only phenomena that can be observed and measured are within the scope of science.

• Testable explanations: Must be falsifiable and based on empirical evidence.

Characteristics Common to All Living Things

Properties of Life

All living organisms share a set of common characteristics that define life. These properties are:

• Order: Organized structure, such as the arrangement of cells in a butterfly's wings.

• Energy Processing: Ability to obtain and use energy (e.g., plants using sunlight for photosynthesis).

• Evolutionary Adaptation: Ability to change over generations (e.g., dolphins and whales adapting to aquatic life).

• Regulation: Maintaining internal balance (e.g., regulating body temperature).

• Response to Environment: Reacting to stimuli (e.g., sunflowers turning toward sunlight).

• Growth and Development: Organisms grow and develop according to genetic instructions.

• Reproduction: Ability to produce new individuals.

Additional info: All living things are made of cells and share these properties.

Cell Types: Prokaryotes vs. Eukaryotes

Prokaryotic Cells

Prokaryotes are organisms whose cells lack membrane-bound organelles, such as a nucleus or chloroplast. They are generally smaller and simpler than eukaryotic cells.

• Domains: Bacteria and Archaea

• Characteristics: Unicellular, can live in diverse environments, lack nucleus

Eukaryotic Cells

Eukaryotes are organisms whose cells contain membrane-bound organelles, including a nucleus. They can be unicellular or multicellular and are generally larger and more complex than prokaryotes.

• Domain: Eukarya

• Characteristics: Can be unicellular or multicellular, have specialized organelles, specific diets

Comparison Table: Prokaryotes vs. Eukaryotes

Feature	Prokaryotes	Eukaryotes
Membrane-bound organelles	No	Yes
Nucleus	No	Yes
Size	Smaller	Larger
Domains	Bacteria, Archaea	Eukarya
Cellularity	Unicellular	Unicellular or multicellular

Domains of Life

The Three Domains

All living organisms are classified into three domains based on cellular structure and molecular evidence:

• Bacteria: Prokaryotic, diverse environments

• Archaea: Prokaryotic, often found in extreme environments

• Eukarya: Eukaryotic, includes plants, animals, fungi, and protists

Additional info: Classification is based on genetic and structural differences among organisms.