Introduction to Science and Biology: Scientific Method, Key Terms, and Characteristics of Life

Science and Its Nature

Definition of Science

Science is a systematic branch of knowledge that uses data from observations and experiments to describe and explain natural phenomena. It relies on empirical evidence and logical reasoning to build a body of knowledge about the universe.

• Empirical evidence: Information acquired by observation or experimentation.

• Natural phenomena: Events or processes that occur in the natural world.

Types of Science

• Basic science: Seeks knowledge for the sake of understanding fundamental principles.

• Applied science: Uses scientific knowledge to solve practical problems.

The Scientific Method

Overview

The scientific method is a logical, systematic approach to solving scientific questions. It involves several key steps that ensure the reliability and validity of scientific findings.

Step 1: Observations

• Scientists make observations using qualitative data (descriptions) and quantitative data (measurements).

• Review of previous research helps build on existing knowledge.

• Formulation of a specific question based on observations.

Step 2: Hypotheses

• A hypothesis is a proposed answer to a specific question.

• It must be testable (can be investigated) and falsifiable (can be proven false).

• Often developed using deductive reasoning (applying general principles to predict specific results).

Step 3: Experimentation

• Experiments are designed to test the hypothesis.

• Data collected can be quantitative (numerical) or qualitative (descriptive).

• Key experimental groups:

  • Experimental group: Receives the variable being tested.

  • Control group: Used for comparison; does not receive the variable.

  • Negative control: Like the experimental group but lacks the variable.

  • Positive control: Group with a known response, used to confirm the experiment is working as expected.

• Prediction: Expected results if the hypothesis is true.

Step 4: Data Analysis

• Data is analyzed and organized, often using tables and graphs.

• Statistics are used to determine if results are due to chance or the effect of the variable.

Step 5: Drawing Conclusions

• Conclusions are based on statistical analysis.

• Results may only apply to the specific instance tested and may not generalize to all situations.

• If there is no significant difference between treatments, they are considered the same.

Step 6: Limitations and Error

• Statistically significant results do not prove a hypothesis.

• Sampling error: The sample may not represent the entire population; larger sample sizes reduce this error.

• Experimental error: Uncontrolled variables or measurement errors can affect results.

• Other hypotheses may not have been tested.

• New experiments may refute previous findings.

Step 7: Communication and Peer Review

• Scientists report results in journals and conferences.

• Work undergoes peer review by other experts to ensure accuracy and validity.

Key Scientific Terms

Hypothesis

• A hypothesis is a proposed answer to a specific question.

• It must be testable and falsifiable.

• Should be specific and based on deductive reasoning (using general principles to predict specific results).

Theory

• A theory is a broad explanation supported by extensive research and experimentation.

• Developed using inductive reasoning (using many observations to form a general principle).

• Theories are not the same as hypotheses; they are broader and supported by more evidence.

• Theories can generate new hypotheses and explain why natural events occur.

Law

• A scientific law describes events that occur in nature under specific conditions.

• Theories do not become laws; laws may be used in forming theories.

• Example: The Law of Gravity allows calculation of attraction between objects, while the Theory of Gravity explains why attraction occurs.

Limitations of Science

• Science is limited to hypotheses that are testable and falsifiable.

• Explanations that are not testable (e.g., supernatural, religious) are outside the scope of science.

Science vs. Pseudoscience

Science	Pseudoscience
Relies on data and scientific inquiry	Claims to be scientific but lacks scientific rigor
Hypotheses must be testable and falsifiable	Beliefs are not falsifiable and may not be testable
Based on analysis of all data	Only data that supports the belief is accepted; contradictory data is ignored

Intelligent Design

• Intelligent design is a philosophy proposing that a designer is responsible for the complexity of life.

• It is not considered science because it is not testable or falsifiable.

Biology: The Study of Life

Definition

Biology is the scientific study of life and living organisms.

Characteristics of Life

• Order and Organization: Living things are highly organized, from molecules to the biosphere.

• Cellular Organization: The cell is the smallest unit of life, separated from the environment by a membrane.

  • Unicellular: Organisms with only one cell (e.g., bacteria).

  • Multicellular: Organisms with many specialized cells (e.g., plants, animals).

• Tissues, Organs, and Systems: In multicellular organisms, similar cells form tissues, tissues form organs, and organs form organ systems.

• Levels of Organization: Organism → Population → Community → Ecosystem → Biosphere.

• Emergent Properties: New properties arise at each level of organization due to interactions among components.

• Homeostasis: Maintenance of a stable internal environment (e.g., water balance, temperature).

• Use of Energy and Materials: Organisms obtain and use energy to carry out life processes.

  • Energy: The capacity to do work.

  • Kinetic energy: Energy of motion.

  • Potential energy: Stored energy due to position or structure.

  • Cellular respiration: Process by which sugars are broken down to produce ATP, the main energy currency of cells.

• Autotrophs: Produce their own sugars (e.g., plants via photosynthesis).

• Heterotrophs: Obtain energy by consuming other organisms (e.g., animals, fungi).

• Response to Stimuli: Organisms respond to changes in their internal or external environment.

• Growth and Development: Increase in size and number of cells; development of specialized structures.

• Reproduction: Production of offspring.

  • Asexual reproduction: Offspring are genetically identical to the parent.

  • Sexual reproduction: Offspring inherit genetic material from two parents and are genetically unique.

• Adaptation and Evolution: Organisms have adaptations that make them better suited to their environment; populations evolve over time.

Themes in Biology

• Emergent Properties: New properties arise at each level of organization due to interactions among components (e.g., water's properties from hydrogen and oxygen interaction).

• Structure and Function: Biological structures are closely related to their functions.

• Interactions: Organisms interact with each other and their environment (e.g., competition, predation, symbiosis).

  • Symbiosis: Close relationship between two species.

  • Parasitism: One benefits, the other is harmed.

  • Commensalism: One benefits, the other is unaffected.

  • Mutualism: Both benefit.

• Regulation: Biological systems are regulated by feedback mechanisms.

  • Negative feedback: The product of a process inhibits the process (e.g., thermostat regulation).

  • Positive feedback: The product intensifies the process (less common).

• Evolution: Populations evolve and adapt to their environment over time.

Taxonomy: Classification of Life

Three Domains of Life

Domain	Cell Type	Key Features	Examples
Bacteria	Prokaryotic	No nucleus or membrane-bound organelles	Escherichia coli, Streptococcus
Archaea	Prokaryotic	Similar to bacteria but with unique genetic and biochemical characteristics; often found in extreme environments	Halophiles, Thermophiles
Eukarya	Eukaryotic	Cells have a nucleus and membrane-bound organelles	Plants, Animals, Fungi, Protists

Kingdoms within Eukarya

• Plantae: Multicellular autotrophs (photosynthetic).

• Fungi: Unicellular or multicellular heterotrophs by absorption (secrete enzymes to digest food externally).

• Animalia: Multicellular heterotrophs by ingestion (digest food internally).

• Protists: Diverse group; mostly unicellular, can be autotrophs or heterotrophs (e.g., amoebas, algae).