BIO 121 Unit 1 Exam Review: Foundations of Biology, Evolution, and the Chemistry of Life

Chapter 1: Biology – The Study of Scientific Life

Properties of Life

• Order: Living things exhibit complex but ordered organization.

• Regulation (Homeostasis): Organisms regulate their internal environment to maintain stable conditions.

• Growth and Development: Information carried by genes controls the pattern of growth and development.

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

• Response to Environment: Living things respond to environmental stimuli.

• Reproduction: Organisms reproduce their own kind.

• Evolutionary Adaptation: Populations evolve over generations as individuals with traits best suited to their environment have greater reproductive success.

Cell

• The cell is the basic unit of life. All organisms are composed of one or more cells.

Domains of Life

• There are three domains of life: Bacteria, Archaea, and Eukarya.

• Bacteria and Archaea are prokaryotic (no nucleus), while Eukarya includes all eukaryotic organisms (with nucleus), such as plants, animals, fungi, and protists.

Emergent Properties & Levels of Biological Organization

• Emergent properties arise at each level of biological organization due to the arrangement and interactions of parts as complexity increases.

Level	Description
Biosphere	All environments on Earth that support life
Ecosystem	All organisms and nonliving components in a particular area
Community	All organisms in an ecosystem
Population	All individuals of a species in a specific area
Organism	An individual living thing
Organ System	Group of organs working together
Organ	Part of an organism with a specific function
Tissue	Group of similar cells performing a function
Cell	Basic unit of life
Organelle	Membrane-bound structure within a cell
Molecule	Cluster of atoms held together by chemical bonds

Science and Inquiry

• Science is a way of knowing, based on inquiry and evidence.

• Inquiry involves asking questions and seeking answers through observation and experimentation.

Hypothesis and Scientific Method

• A hypothesis is a tentative answer to a question, testable and falsifiable.

• The scientific method involves observation, forming hypotheses, experimentation, data collection, and drawing conclusions.

• Independent variable: The factor manipulated in an experiment.

• Dependent variable: The factor measured in response to changes in the independent variable.

• Controlled experiment: An experiment in which only one variable is changed at a time.

• Qualitative data: Descriptive data (e.g., color, texture).

• Quantitative data: Numerical data (e.g., mass, volume).

• Theory: A broad, well-supported explanation for a wide range of observations.

Example: Beach Mouse Experiment

• Researchers tested how coat color affects predation on beach mice by placing models of different colors in different habitats and measuring predation rates.

Three Spheres Influencing Hypothesis Testing

• Society, Technology, and Science interact to influence hypothesis testing and scientific progress.

Relationship Between Science and Technology

• Science seeks to understand natural phenomena; technology applies scientific knowledge for practical purposes.

Evolution, Natural Selection, and Artificial Selection

• Evolution: The process of change over time that has resulted in the diversity of life.

• Natural selection: The process by which individuals with advantageous traits survive and reproduce more successfully.

• Artificial selection: Humans select and breed organisms for desired traits (e.g., dog breeds).

Energy Flow and Matter Cycling

• Energy flows through ecosystems (usually entering as sunlight and exiting as heat), while matter cycles within ecosystems.

Chapter 13: How Populations Evolve

Darwin and the Theory of Evolution

• Charles Darwin traveled on the HMS Beagle, especially to the Galápagos Islands, and developed the theory of evolution by natural selection.

• Adaptation: Inherited traits that enhance an organism's ability to survive and reproduce in a particular environment.

Fossils and Whale Evolution

• Fossils are preserved remains or traces of organisms from the past, providing evidence for evolution.

• Whale evolution is documented by transitional fossils showing the shift from land-dwelling to aquatic life.

Homology, Vestigial Structures, and Evolutionary Trees

• Homology: Similarity in characteristics resulting from shared ancestry (e.g., forelimbs of mammals).

• Vestigial structures: Remnants of features that served important functions in ancestors (e.g., human appendix).

• Evolutionary tree: Diagram showing evolutionary relationships among species.

Natural Selection and Artificial Selection

• Natural selection leads to adaptation and evolution; artificial selection is human-directed evolution.

Three Key Points of Evolution by Natural Selection

• 1. Individuals do not evolve; populations do.

• 2. Natural selection can only amplify or diminish heritable traits.

• 3. Evolution is not goal-directed; it is a remodeling process.

Population, Heritable Traits, and Genetic Variation

• Population: A group of individuals of the same species living in the same area.

• Heritable traits: Traits that are passed from parents to offspring.

• Genetic variation arises from mutations, sexual reproduction, and gene flow.

Observations of Natural Selection in Action

• Examples include the evolution of pesticide resistance in insects and antibiotic resistance in bacteria.

Mutations and Gene Pool

• Mutation: A change in DNA sequence; can introduce new genetic variation.

• Gene pool: The total collection of genes in a population at any one time.

Microevolution

• Microevolution is a change in the gene pool of a population over generations.

Chapter 15: Tracing Evolutionary History

Macroevolution vs. Microevolution

• Microevolution: Small-scale changes in allele frequencies within a population.

• Macroevolution: Large-scale evolutionary changes, such as the origin of new species.

Origin of Earth and Stromatolites

• Earth formed about 4.6 billion years ago.

• Stromatolites: Layered rocks formed by prokaryotes (cyanobacteria) about 3.5 billion years ago; evidence of early life.

Four Stages of First Life

1. Abiotic synthesis of small organic molecules (e.g., amino acids, nucleotides).

2. Joining of these molecules into polymers (e.g., proteins, nucleic acids).

3. Packaging of molecules into protocells (membrane-bound droplets).

4. Origin of self-replicating molecules (e.g., RNA).

Oparin-Haldane Hypothesis and Miller Experiment

• Oparin and Haldane proposed that early Earth's atmosphere could have produced organic molecules from inorganic precursors.

• The Miller experiment simulated early Earth conditions and produced amino acids, supporting this hypothesis.

Oxygen in Early Earth

• Early Earth had little O2; the appearance of photosynthetic organisms added O2 to the atmosphere.

• O2 would have been problematic for the origin of life because it can break down organic molecules.

Three Stages of First Cells

• 1. Synthesis of organic molecules

• 2. Formation of protocells

• 3. Origin of self-replicating molecules

• These stages are essential for the evolution of life from non-life.

Chapter 2: The Chemical Basis of Life

Matter, Elements, and Compounds

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

• There are about 92 naturally occurring elements; the top four in living organisms are Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N).

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

• Trace elements: Required in small amounts (e.g., iron, iodine); essential for health.

Atoms and Subatomic Particles

• Atom: Smallest unit of an element.

• Subatomic particles: Protons (positive, in nucleus), Neutrons (neutral, in nucleus), Electrons (negative, orbit nucleus).

• Atomic number: Number of protons.

• Mass number: Protons + neutrons.

• Atomic mass: Average mass of an atom (close to mass number).

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Radioactive isotopes: Unstable isotopes that decay, emitting radiation; used in dating fossils and medical imaging.

Electron Shells and Chemical Bonds

• Electrons are arranged in shells; chemical behavior depends on electron arrangement.

• Ionic bond: Attraction between oppositely charged ions; electrons are transferred.

• Covalent bond: Sharing of electron pairs between atoms.

• Carbon can form four covalent bonds.

• Nonpolar covalent bond: Electrons shared equally.

• Polar covalent bond: Electrons shared unequally, creating partial charges.

• Polarity: Unequal distribution of charge in a molecule.

• Ion: Atom or molecule with a charge due to loss/gain of electrons.

• Salt: Compound formed from ionic bonds (e.g., NaCl).

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

• Polar molecule: Molecule with uneven charge distribution (e.g., water).

Chemical Reactions

• Chemical reaction: Making and breaking of chemical bonds, leading to changes in composition.

• Reactants: Starting materials.

• Products: Resulting substances.

Properties of Water

• Cohesion: Attraction between molecules of the same substance (e.g., water molecules stick together).

• Adhesion: Attraction between different substances (e.g., water to plant cell walls).

• Surface tension: Measure of how difficult it is to stretch or break the surface of a liquid.

• Thermal energy: Total energy of molecular motion; water absorbs/releases heat slowly.

• Heat: Transfer of thermal energy.

• Temperature: Average kinetic energy of molecules.

• Evaporative cooling: Surface cools as molecules with highest energy evaporate.

• Ice is less dense than liquid water because hydrogen bonds hold molecules apart; thus, ice floats.

Solutions, Acids, Bases, and pH

• Solution: Homogeneous mixture of two or more substances.

• Solvent: Dissolving agent (e.g., water).

• Solute: Substance dissolved.

• Aqueous solution: Solution where water is the solvent.

• pH scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), with 7 as neutral.

• Acid: Substance that increases H+ concentration.

• Base: Substance that decreases H+ concentration.

• Buffer: Substance that minimizes changes in pH.

• Ocean acidification: Decreasing pH of ocean due to absorption of excess atmospheric CO2.

Chapter 3: The Molecules of Cells

Organic Compounds, Isomers, and Functional Groups

• Organic compounds: Carbon-based molecules.

• Isomers: Compounds with the same formula but different structures.

• Hydrocarbons: Molecules consisting only of carbon and hydrogen.

• Functional groups: Groups of atoms that affect a molecule's function (e.g., hydroxyl, carboxyl, amino, phosphate).

Macromolecules: Monomers and Polymers

• Macromolecules: Large molecules essential for life (carbohydrates, lipids, proteins, nucleic acids).

• Monomers: Building blocks of polymers.

• Polymers: Long chains of monomers.

Macromolecule	Monomer	Polymer	Function
Carbohydrate	Monosaccharide	Polysaccharide	Energy, structure
Lipid	Fatty acid, glycerol	Triglyceride, phospholipid	Energy storage, membranes
Protein	Amino acid	Polypeptide	Catalysis, structure, transport
Nucleic Acid	Nucleotide	DNA/RNA	Genetic information

Dehydration Reaction and Hydrolysis

• Dehydration reaction: Joins monomers by removing water to form polymers.

• Hydrolysis: Breaks polymers into monomers by adding water.

Enzymes

• Enzymes: Proteins that speed up chemical reactions by lowering activation energy.

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose).

• Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose, chitin).

• Starch: Storage in plants.

• Glycogen: Storage in animals.

• Cellulose: Structural in plant cell walls.

• Chitin: Structural in fungi and arthropod exoskeletons.

Lipids

• Lipids: Hydrophobic molecules, not true polymers.

• Fats: Glycerol + 3 fatty acids; energy storage.

• Unsaturated fats: One or more double bonds; liquid at room temperature; found in plants/fish.

• Saturated fats: No double bonds; solid at room temperature; found in animal fats.

• Trans fats: Unsaturated fats artificially hydrogenated; associated with health risks.

• Phospholipids: Glycerol + 2 fatty acids + phosphate; major component of cell membranes; hydrophilic head, hydrophobic tails.

• Steroids: Four fused rings; includes cholesterol and hormones.

• Cholesterol: Component of animal cell membranes; precursor for steroid hormones.

• Anabolic steroids: Synthetic variants of testosterone; can have health risks.

• Defining feature: Hydrophobicity.

Proteins

• Proteins: Polymers of amino acids; perform many functions (enzymes, structure, transport, etc.).

• Amino acids: 20 types; each has an amino group, carboxyl group, hydrogen, and R group (side chain).

• Peptide bond: Covalent bond linking amino acids.

• Polypeptide: Chain of amino acids.

• Denaturation: Loss of protein structure (and function) due to environmental changes.

• Structure-function relationship: Protein function depends on its 3D shape.

Level	Description
Primary	Sequence of amino acids
Secondary	Coiling/folding (alpha helix, beta sheet)
Tertiary	3D shape of polypeptide
Quaternary	Association of multiple polypeptides

Nucleic Acids: DNA and RNA

• Nucleotides: Monomers of nucleic acids; each has a sugar, phosphate group, and nitrogenous base.

• DNA: Double-stranded; stores genetic information.

• RNA: Single-stranded; involved in protein synthesis.

• DNA and RNA differ in sugar (deoxyribose vs. ribose), bases (thymine in DNA, uracil in RNA), and structure.

Lactose-Lactase-DNA Connection

• Lactase is an enzyme (protein) that breaks down lactose (a disaccharide); the ability to produce lactase is encoded by DNA.

Additional info: For all terms, be able to define, explain, and provide examples as indicated in the review sheet. Use diagrams and figures from your textbook for visual reinforcement where possible.