General Biology and Biological Classification Flashcards

Biological Organization and the Definition of Biology

• Definition of Biology: Biology is defined as the science of life.

• Levels of Biological Organization: All living things share basic levels of biological organization, structured sequentially from the most specific level to the most broad:   $\text{Atoms} \rightarrow \text{Molecules} \rightarrow \text{Organelles} \rightarrow \text{Cells} \rightarrow \text{Tissues} \rightarrow \text{Organs} \rightarrow \text{Organism} \rightarrow \text{Population} \rightarrow \text{Community} \rightarrow \text{Ecosystem} \rightarrow \text{Biosphere}$

• Smallest Unit of Life: The cell is the smallest functioning unit to be considered alive and to be considered an organism.

Fundamental Similarities Across Living Organisms

• Shared Characteristics Among Diverse Organisms: Despite the vast diversity observed across living organisms, all cells and organisms share four fundamental similarities:

  • All organisms are made of cells.

  • All cells have similar molecules.

  • All cells do similar chemical reactions.

  • All cells use the same genetic material ($\text{DNA}$).

• Explaining Unity and Diversity: Evolutionary theory accounts for both the broad diversity of life and the fundamental similarities shared among all living organisms.

Classification and the Three Domains of Life

• Major Biological Domains: All living organisms are classified into three major overarching groups known as the 3 Domains:

  • Bacteria

  • Archaea

  • Eukarya

• Critical Factors in Classification: The classification of any organism depends on three primary factors:

  • Number of cells that the organism is made of:

  • Unicellular: Organisms made of one cell.

  • Multicellular: Organisms made of many cells.

  • Cellular structure (complexity of cells when viewed microscopically):

  • Prokaryotic: Cells that do not have a nucleus.

  • Eukaryotic: Cells that have a nucleus.

  • How food is obtained:

  • Ingested: Organisms eat or consume food.

  • Made: Organisms make their own food, usually through Photosynthesis.

  • Absorbed: Organisms take in nutrients from their surroundings.

• Domain Characteristics Summary:

  • Bacteria:

  • Size: Relatively small

  • Number of cells: Unicellular

  • Cellular complexity: Prokaryotic

  • Food acquisition: Absorb

  • Archaea:

  • Size: Relatively small

  • Number of cells: Unicellular

  • Cellular complexity: Prokaryotic

  • Food acquisition: Absorb

  • Eukarya:

  • Size: Relatively large

  • Number of cells: Variable

  • Cellular complexity: Eukaryotic

  • Food acquisition: Variable

Homeostasis in Living Organisms

• Definition of Homeostasis: Homeostasis is defined as the maintenance of constant internal conditions despite external fluctuations.

• Human Physiological Examples:

  • Shivering when exposed to cold conditions.

  • Sweating when exposed to hot conditions.

• Importance: The maintenance of homeostasis helps the body maintain stable internal regulation necessary for survival.

• Mechanism of Regulation: Organisms maintain homeostasis through chemical messengers known as hormones.

• Consequences of Homeostatic Failure:

  • Inability to maintain homeostasis leads to a diseased state.

  • Failure to restore homeostasis results in death.

The Nature of Science and Scientific Thinking

• Perception versus Reality of Science:

  • Science is often portrayed as a rigid process based on the premise that following the scientific method exactly guarantees valid results.

  • In reality, the scientific method serves merely as a set of guidelines governing how science should theoretically be done; actual scientific practice is very creative.

• Steps of the Scientific Method: The theoretical progression of the scientific method follows these standard steps:

  1. Observation

  2. Ask a question

  3. Form a hypothesis

  4. Conduct an experiment

  5. Collect and analyze data

  6. Draw a conclusion

  7. Communicate results

• Critique and Evaluation of Scientific Claims:

  • Science is not always ethical and does not automatically yield findings that must be accepted as undeniable fact.

  • Science must always be subjected to rigorous critique, including evaluation by non-scientists.

  • Real-world scientific practice contains a substantial amount of bad science alongside good science.

  • Statements in media or advertising asserting that "scientific studies prove…" should never be assumed true without evaluation.

  • The specific design, execution, and interpretation of scientific studies are crucial factors in determining their validity.

  • Developing the capacity to critique and evaluate scientific claims—especially regarding health and daily living—is an essential skill, making skepticism a key tool.