General Biology: Core Concepts, Hierarchies, and Scientific Method

THE 7 COMMON PROPERTIES OF LIFE

Order

All living organisms exhibit a specific order or structure, which is fundamental to their identity and function.

• Order refers to the organized structure of living things.

• This structure varies among different organisms (e.g., plants, animals, humans).

• Example: The vein structure in a leaf is different from the vein structure in a human; each is adapted to its organism's needs.

Reproduction

Reproduction is essential for the continuation of life and the passing of genetic information to the next generation.

• Organisms must reproduce to pass on genes.

• Evolution (the core theme of biology) depends on reproduction.

Energy Processing

Living organisms require energy to perform work, grow, and maintain their structures.

• Energy is obtained from food, which contains chemical energy.

• The body cannot convert food directly into usable energy without processing it into ATP (adenosine triphosphate).

• ATP is the universal energy currency in cells.

• No ATP = cell death. ATP is produced from food via cellular respiration.

Response to Environment

Organisms detect and respond to environmental stimuli to survive and maintain homeostasis.

• Responses depend on the situation (e.g., shivering to generate heat, sweating to lose heat).

• These responses are part of regulation, which maintains internal stability.

• Example: Internal body temperature regulation (thermoregulation), osmoregulation (water and salt balance).

Regulation

Regulation is the ability to control an organism's internal environment within limits that sustain life.

• Maintaining homeostasis is crucial for survival.

• Example: Regulation of body temperature, blood sugar, and water balance.

Evolutionary Adaptation

Organisms adapt to their environment over generations through evolution, which enables survival and reproduction.

• Adaptation is the result of evolutionary processes.

• Genes that confer advantages are passed on to future generations.

#1 LIFE'S HIERARCHY OF ORGANIZATION

Biological organization is structured from the most complex to the simplest levels, with new properties emerging at each level (emergent properties).

• Hierarchy: Biosphere → Ecosystem → Community → Population → Organism → Organ System → Organ → Tissue → Cell/Organelle → Molecule/Atom

Biosphere

• The broadest level, encompassing all life-supporting environments on Earth.

Ecosystem

• Includes all living (biotic) and non-living (abiotic) components interacting in a particular area.

• Example: A pond ecosystem includes fish, frogs, plants, rocks, and water.

Community

• All the different species living together in an ecosystem.

• Communities are defined by the variety of species, colors, shapes, etc.

Population

• Members of the same species living in the same area at the same time.

Organism

• An individual living entity made up of organ systems.

Organ Systems and Organs

• Organ systems are groups of organs that work together (e.g., reproductive system).

• Organs are made of tissues (e.g., heart, ovaries, testes).

Tissues

• Groups of similar cells performing a specific function.

• Example: Heart tissue is made of muscle cells that contract to pump blood.

Cells and Organelles

• The cell is the basic unit of life, containing organelles (e.g., nucleus).

Molecules and Atoms

• Molecules are made of atoms, the smallest structural units of matter.

• Atoms make up all living and non-living things.

#2 ENERGY AND MATTER

Energy and matter are essential for life, cycling through ecosystems and enabling biological processes.

• The primary source of energy is sunlight.

• Photosynthesis converts light energy into chemical energy (mainly sugars/carbohydrates).

• Energy flows in one direction: Sunlight → Primary producers → Secondary consumers → Decomposers → Lost as heat.

• All matter is recycled, but energy is not.

#3 INFORMATION

Genetic information is stored in DNA, which directs the growth, development, and functioning of all living things.

• Cells contain DNA, which is organized into chromosomes.

• Genetic information flows from DNA → RNA → Protein (the "central dogma").

• Proteins carry out the functions encoded by genes (e.g., keratin in hair).

#4 INTERACTION

Biological systems are regulated by feedback mechanisms that maintain stability and function.

• Feedback regulation involves processes being controlled by their outputs.

• Negative feedback: Accumulation of an end product slows the process (e.g., high ATP levels inhibit further ATP production).

• Positive feedback: Accumulation of an end product speeds up the process (e.g., blood clotting).

CORE THEME OF BIOLOGY: EVOLUTION

Evolution

Evolution is the process by which species change over time, leading to the diversity of life.

• All living things share a common ancestor.

• Evolution is the unifying theme of biology.

The Tree of Life

• Represents the evolutionary relationships among species.

• Branches indicate divergence from common ancestors.

• Three main domains: Bacteria, Archaea, Eukarya.

Two Types of Cells

Prokaryotic Cells	Eukaryotic Cells
No organelles Smaller in size Domains: Bacteria, Archaea	Have organelles Larger in size Domain: Eukarya (plants, animals, fungi, protists)

CHAPTER 1: NATURAL SELECTION

Natural Selection

Natural selection is the process by which organisms with beneficial traits are more likely to survive and reproduce.

• "Survival of the fittest" means more offspring are produced than can survive.

• Traits that enhance survival and reproduction become more common in a population.

• Example: Darwin's finches on the Galapagos Islands.

Reproduction and Survival

• Individuals in a population vary in traits (e.g., hair color).

• Traits are inherited by offspring.

• Overproduction of offspring leads to competition for resources.

Antibiotic Resistance

• Bacteria can develop resistance to antibiotics through natural selection.

• Resistant bacteria survive and reproduce, passing on resistance genes.

• Bacteria can switch genes on and off, allowing rapid adaptation.

SCIENTIFIC INQUIRY

Discovery Science

• Involves observing and describing nature.

Inductive Reasoning

• Specific observations lead to general conclusions.

• Example: Observing that all animals have cells leads to the conclusion that "all animals have cells."

Hypothesis-Based Science

• Begins with a question based on observations.

• Formulates a hypothesis (a proposed explanation).

• Example: "Why is it sunny?" leads to a hypothesis about atmospheric conditions.

Deductive Reasoning

• Starts with a general idea and makes specific predictions.

• Example: If all organisms have cells and humans are organisms, then humans have cells.

Scientific Method

1. Observation

2. Hypothesis

3. Alternative hypothesis

4. Prediction

5. Experiment

6. Result

7. Conclusion

• Hypotheses are proposed explanations that can be tested.

• Alternative hypotheses may exist.

• Experiments must be repeatable for results to be accepted as theory.

Theory and Model

• A theory is a broad explanation supported by a large body of evidence.

• A model is a representation of a process or system.

• If a hypothesis is repeatedly supported, it may become a theory.

Additional info: These notes are structured to cover foundational concepts in General Biology, including the properties of life, biological organization, energy flow, genetic information, evolution, natural selection, and the scientific method. Key terms, examples, and processes are expanded for clarity and exam preparation.