Fundamental Concepts in General Biology: Properties of Life, Biological Organization, and Chemistry of Life

Properties of Life

Defining Characteristics of Living Organisms

All living things share a set of fundamental properties that distinguish them from non-living matter. Understanding these properties is essential for studying biology.

• Order: Living organisms exhibit complex organization, from molecules to cells to tissues.

• Regulation: Organisms maintain stable internal environments (homeostasis).

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

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

• Response to Environment: Living things respond to stimuli in their environment.

• Reproduction: Organisms reproduce, passing genetic material to offspring.

• Evolutionary Adaptation: Populations evolve over generations through natural selection.

Biological Organization

Levels of Organization in Biology

Biology studies life at various levels of organization, from the smallest units to the largest systems.

• Atom: The basic unit of matter.

• Molecule: Two or more atoms bonded together.

• Organelle: Specialized structures within cells (e.g., mitochondria).

• Cell: The basic unit of life.

• Tissue: Groups of similar cells performing a function.

• Organ: Structures composed of tissues with specific functions.

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

• Organism: An individual living thing.

• Population: Group of organisms of the same species in an area.

• Community: All populations in a given area.

• Ecosystem: Community plus nonliving environment.

• Biosphere: All ecosystems on Earth.

Properties of Water

Unique Features of Water Essential for Life

Water is vital for life due to its unique chemical and physical properties.

• Cohesion: Water molecules stick together due to hydrogen bonding.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water resists temperature changes.

• High Heat of Vaporization: Water requires much energy to change from liquid to gas.

• Expansion upon Freezing: Ice is less dense than liquid water.

• Versatility as a Solvent: Water dissolves many substances.

• Surface Tension: Water has a high surface tension due to hydrogen bonds.

• Capillary Action: Water moves up narrow tubes against gravity.

Basic Chemistry for Biology

Elements, Atoms, and Subatomic Particles

Understanding the structure of atoms and elements is foundational for biology.

• Trace Elements: Elements required in small amounts for life (e.g., iron, iodine).

• Subatomic Particles:

  • Proton: Positively charged particle in the nucleus.

  • Neutron: Neutral particle in the nucleus.

  • Electron: Negatively charged particle orbiting the nucleus.

• Atomic Mass: Sum of protons and neutrons in an atom.

• Atomic Number: Number of protons in an atom.

• Valence Shell: Outermost electron shell, determines chemical reactivity.

• Electronegativity: Atom's ability to attract electrons in a bond.

Chemical Bonds

Atoms interact through chemical bonds to form molecules essential for life.

• Covalent Bond: Atoms share electrons.

  • Polar Covalent Bond: Electrons shared unequally, creating partial charges (e.g., water).

  • Nonpolar Covalent Bond: Electrons shared equally.

• Ionic Bond: Electrons transferred from one atom to another, creating ions.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., between water molecules).

Ions and Solutions

Ions and solutions are important for biological processes, including nerve impulses and cellular transport.

• Ions: Charged atoms or molecules (cations are positive, anions are negative).

• Solvent: Substance that dissolves other substances (water is the universal solvent).

• Solute: Substance dissolved in a solvent.

• Solution: Homogeneous mixture of solute and solvent.

Scientific Method

Process of Scientific Inquiry

The scientific method is a systematic approach to investigating natural phenomena.

• Independent Variable: The factor that is changed or manipulated in an experiment.

• Dependent Variable: The factor that is measured or observed.

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

Evolution and Natural Selection

Mechanisms of Biological Change

Evolution explains the diversity of life through changes in populations over time, driven by natural selection.

• Evolution: Change in the genetic composition of populations over generations.

• Natural Selection: Process by which individuals with advantageous traits survive and reproduce more successfully.

DNA

Genetic Material of Life

DNA (deoxyribonucleic acid) is the molecule that stores genetic information in all living organisms.

• Structure: Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).

• Function: Encodes instructions for building proteins and regulating cellular activities.

Chemical Reactions in Biology

Reactants and Products

Chemical reactions transform substances in biological systems.

• Reactants: Substances that start a chemical reaction.

• Products: Substances formed as a result of a chemical reaction.

Example Equation:

Photosynthesis:

$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$

Summary Table: Types of Chemical Bonds

Bond Type	Description	Example
Covalent (Polar)	Electrons shared unequally	Water ($H_2O$)
Covalent (Nonpolar)	Electrons shared equally	Methane ($CH_4$)
Ionic	Electrons transferred, forming ions	Sodium chloride ($NaCl$)
Hydrogen	Weak attraction between molecules	Between water molecules

Additional info: Some content was inferred and expanded for completeness, such as the full list of biological organization levels and detailed properties of water.