Introduction to Biology

Properties of Life

Biology is the study of living organisms and their interactions with the environment. All living things share certain properties that define life.

• Order: Living things exhibit complex but ordered organization. Example: The structure of a sunflower.

• Regulation: Organisms regulate their internal environment. Example: Birds maintaining constant body temperature.

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA. Example: A caterpillar transforming into a butterfly.

• Energy Processing: Living things obtain and use energy. Example: Plants performing photosynthesis.

• Response to Environment: Organisms respond to environmental stimuli. Example: Venus flytrap closing when touched.

• Reproduction: Organisms reproduce their own kind. Example: Birds laying eggs.

• Evolutionary Adaptation: Populations evolve over generations. Example: Camouflage in insects.

Emergent Properties

Emergent properties are new characteristics that arise at each level of biological organization, due to the arrangement and interactions of parts as complexity increases.

• Example 1: A functioning bicycle emerges only when all necessary parts are connected in the correct way.

• Example 2: The brain's ability to think and feel emerges from the interactions of billions of neurons.

Biological Organization

Levels of Biological Organization

Life is organized in a hierarchy from the largest to the smallest scale:

• Biosphere: All life on Earth and all places where life exists.

• Ecosystem: All living things in a particular area, along with nonliving components.

• Community: All organisms in an ecosystem.

• Population: All individuals of a species within an area.

• Organism: An individual living thing.

• Organ/Organ System: Body parts that perform a specific function.

• Tissues: Groups of similar cells performing a function.

• Cells: The basic unit of life.

• Organelles: Functional components within cells.

• Molecules: Chemical structures consisting of two or more atoms.

Cell Types

• Eukaryotic Cell: Contains a nucleus and membrane-bound organelles.

• Prokaryotic Cell: Lacks a nucleus and membrane-bound organelles.

Genetic Information

• DNA: The molecule that stores genetic information.

• Genes: Units of inheritance made of DNA.

• Genome: The complete set of genetic material in an organism.

Feedback Mechanisms

• Negative Feedback: A process in which a system is regulated by reducing the output or activity when it exceeds a set point.

• Positive Feedback: A process in which the end product of an action causes more of that action to occur.

Evolution and Classification

Domains of Life

All life is classified into three domains:

Levels of Classification

From broadest to most specific:

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Darwin's Theory of Evolution

• Main Points: Species show evidence of "descent with modification" from common ancestors; natural selection is the mechanism for evolution.

• Natural Selection: Individuals with traits best suited to their environment are more likely to survive and reproduce.

The Process of Science

Data and Hypotheses

• Data: Recorded observations or items of information.

• Quantitative Data: Numerical measurements (can be graphed).

• Qualitative Data: Descriptions (e.g., field sketches).

• Hypothesis: A testable explanation for an observation.

• Qualities of a Scientific Hypothesis: Must be testable and falsifiable.

• Scientific Hypotheses: Are never proved, only supported or refuted by evidence.

Basic Chemistry for Biology

Matter and Elements

• Matter: Anything that takes up space and has mass.

• Element: A substance that cannot be broken down to other substances by chemical means.

• Compound: A substance consisting of two or more elements in a fixed ratio.

• Essential Element: An element required for an organism to survive, grow, and reproduce.

• Trace Element: An element required by an organism in only minute quantities.

Atomic Structure

• Proton: Positively charged subatomic particle in the nucleus.

• Neutron: Neutrally charged subatomic particle in the nucleus.

• Electron: Negatively charged subatomic particle orbiting the nucleus.

• Atomic Number: Number of protons in an atom.

• Atomic Mass: Sum of protons and neutrons.

Electron Shells and Energy

• Electrons are arranged in shells around the nucleus.

• Valence electrons are those in the outermost shell and are involved in chemical reactions.

• Potential Energy: Energy that matter possesses because of its location or structure.

Chemical Bonds

• Covalent Bond: Sharing of electron pairs between atoms.

• Nonpolar Covalent Bond: Electrons are shared equally.

• Polar Covalent Bond: Electrons are shared unequally, leading to partial charges.

• Ionic Bond: Transfer of electrons from one atom to another, resulting in oppositely charged ions.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom.

• Van der Waals Interactions: Weak attractions between molecules or parts of molecules that result from transient local partial charges.

Electronegativity

• Electronegativity: The attraction of a particular atom for the electrons of a covalent bond.

Table: Molecules and Compounds

Chemical Reactions in Biology

• Chemical Reaction: The making and breaking of chemical bonds, leading to changes in the composition of matter.

• Photosynthesis Equation:

• Reactants: Carbon dioxide and water

• Products: Glucose and oxygen

Properties of Water

Polarity and Hydrogen Bonding

• Water is a polar molecule, with oxygen being more electronegative than hydrogen.

• Hydrogen bonds form between the slightly positive hydrogen of one water molecule and the slightly negative oxygen of another.

Emergent Properties of Water

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

• Adhesion: Water molecules stick to other substances.

• Surface Tension: A measure of how difficult it is to stretch or break the surface of a liquid.

• High Specific Heat: Water can absorb or release a large amount of heat with only a slight change in its own temperature.

• Heat of Vaporization: The quantity of heat a liquid must absorb for 1 g to be converted to gas.

• Expansion upon Freezing: Ice is less dense than liquid water, so it floats.

• Versatile Solvent: Water dissolves more substances than any other liquid.

Solvent of Life

• Solution: A liquid that is a homogeneous mixture of two or more substances.

• Solvent: The dissolving agent of a solution.

• Solute: The substance that is dissolved.

• Hydrophilic: Substances that have an affinity for water.

• Hydrophobic: Substances that do not have an affinity for water.

Biological Importance of Water's Properties

• Moderation of temperature helps maintain stable environments for organisms.

• Ice floating insulates bodies of water, protecting aquatic life in winter.

• Water's solvent abilities facilitate chemical reactions in cells.

Additional info: These notes are based on foundational concepts in introductory biology, including the chemistry of life and the unique properties of water essential for life on Earth.