General Biology I: Study Guide for Exam 1 (Chapters 1–4)

Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry

Key Concepts and Vocabulary

• Biology: The scientific study of life, characterized by properties such as order, regulation, energy processing, growth and development, response to the environment, reproduction, and evolutionary adaptation.

• Levels of Biological Organization: Includes atom, molecule, cell, tissue, organ, organ system, organism, population, community, ecosystem, and biosphere.

• Hypothesis: A testable explanation for an observation, phenomenon, or scientific problem.

• Scientific Inquiry: The process by which scientists ask questions, make observations, form hypotheses, conduct experiments, and draw conclusions.

• Experimental Design: Involves variables such as independent variable (manipulated), dependent variable (measured), control group, and experimental group.

Scientific Method

• Steps: Observation, question, hypothesis, prediction, experiment, analysis, conclusion.

• Controlled Experiment: Only one variable is changed at a time; includes control and experimental groups.

Examples and Applications

• Example: Testing the effect of sunlight on plant growth by comparing plants exposed to sunlight (experimental group) and those kept in the dark (control group).

Additional info: Understanding the difference between qualitative and quantitative data is important in scientific inquiry.

Chapter 2: The Chemical Context of Life

Atoms, Elements, and Compounds

• Atom: The smallest unit of matter, composed of protons, neutrons, and electrons.

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

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

• Trace Elements: Elements required by an organism in minute quantities (e.g., iron, iodine).

Chemical Bonds and Interactions

• Covalent Bond: Sharing of electron pairs between atoms.

• 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 (e.g., oxygen, nitrogen).

• Polar vs. Nonpolar Covalent Bonds: Polar bonds have unequal sharing of electrons; nonpolar bonds have equal sharing.

Water and Its Properties

• Cohesion: Attraction between molecules of the same substance (important for water transport in plants).

• Adhesion: Attraction between different substances.

• Specific Heat: Amount of heat required to change the temperature of a substance; water has high specific heat.

• Evaporation: Process by which molecules at the surface of a liquid absorb enough energy to change to a gas.

• Hydrophilic vs. Hydrophobic: Hydrophilic substances interact with water; hydrophobic substances do not.

Acids, Bases, and pH

• pH Scale: Measures the concentration of hydrogen ions; ranges from 0 (acidic) to 14 (basic), with 7 as neutral.

• Buffer: Substance that minimizes changes in pH.

• Ocean Acidification: Decrease in ocean pH due to absorption of excess atmospheric CO2.

Example Table: Types of Chemical Bonds

Bond Type	Description	Example
Covalent	Electron sharing	H2O
Ionic	Electron transfer	NaCl
Hydrogen	Weak attraction between H and electronegative atom	Between water molecules

Chapter 3: Water and Life

Carbon and Molecular Diversity

• Organic Chemistry: Study of carbon-containing compounds.

• Isomer: Compounds with the same molecular formula but different structures (structural, cis-trans, enantiomers).

• Functional Groups: Specific groups of atoms within molecules that have characteristic properties (e.g., hydroxyl, carboxyl, amino, phosphate).

Macromolecules

• Polymer: Long molecule consisting of many similar building blocks (monomers).

• Dehydration Reaction: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Carbohydrates, Lipids, Proteins, Nucleic Acids

• Carbohydrates: Sugars and polymers of sugars; function as energy source and structural material.

• Lipids: Hydrophobic molecules including fats, phospholipids, and steroids.

• Proteins: Polymers of amino acids; function in catalysis, structure, transport, and more.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets formed by hydrogen bonding.

• Tertiary Structure: 3D folding due to side chain interactions.

• Quaternary Structure: Association of multiple polypeptide chains.

Example Table: Levels of Protein Structure

Level	Description	Bond/Interaction
Primary	Amino acid sequence	Peptide bonds
Secondary	Alpha helix, beta sheet	Hydrogen bonds
Tertiary	3D folding	Hydrophobic interactions, disulfide bridges
Quaternary	Multiple polypeptides	Same as tertiary

Chapter 4: A Tour of the Cell

Cell Types and Structures

• Prokaryotic Cells: Lack a nucleus; include Bacteria and Archaea.

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles; include plants, animals, fungi, and protists.

• SEM vs. TEM: Scanning Electron Microscopy (SEM) provides surface images; Transmission Electron Microscopy (TEM) provides internal structure images.

Cell Organelles and Functions

• Nucleus: Contains DNA; control center of the cell.

• Ribosomes: Sites of protein synthesis; found in cytoplasm or on rough ER.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Lysosomes: Contain digestive enzymes; break down waste.

• Vacuoles: Storage and structural support in plant cells.

• Mitochondria: Site of cellular respiration; produce ATP.

• Chloroplasts: Site of photosynthesis in plant cells.

• Cytoskeleton: Provides structural support; includes microtubules, microfilaments, and intermediate filaments.

• Cell Wall: Found in plants, fungi, and some protists; provides support and protection.

• Cilia and Flagella: Structures for cell movement.

Example Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic	Eukaryotic
Nucleus	Absent	Present
Organelles	Few, not membrane-bound	Many, membrane-bound
Size	Small (1-10 μm)	Larger (10-100 μm)
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Additional info: Understanding the function and structure of each organelle is essential for explaining how cells operate and interact with their environment.