General Biology Exam 1 Study Guide: Chapters 1–3

Chapter 1: Introduction to Life and Scientific Inquiry

Characteristics of Life

Living things share several fundamental characteristics that distinguish them from non-living matter.

• Order: Living organisms exhibit complex but ordered organization.

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

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Energy Processing: Living things acquire and use energy for metabolism and work.

• Response to Environment: Organisms respond to environmental stimuli.

• Reproduction: Organisms reproduce their own kind.

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

Examples: A plant growing toward light (response to the environment), a dog maintaining body temperature (regulation).

Classification of Living Things

Biologists classify living things to organize and understand the diversity of life.

• Taxonomy: The science of naming, describing, and classifying organisms.

• Domains: The broadest classification: Bacteria, Archaea, and Eukarya.

• Emergent Properties: New properties that arise at each level of biological organization, not present at the preceding level.

Example: A cell is alive, but its individual molecules are not.

Scientific Method

The scientific method is a systematic approach to understanding the natural world.

• Steps: Observation, Question, Hypothesis, Prediction, Experiment, Analysis, Conclusion.

• Hypothesis: A testable explanation for an observation.

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

• Difference: A hypothesis is a specific, testable statement; a theory is a comprehensive explanation supported by evidence.

• Scientific Literacy: The ability to understand scientific concepts and processes.

Example: Hypothesis: "Plants grow faster under blue light." Theory: "Cell theory" states all living things are made of cells.

Chapter 2: Chemical Context of Life

Periodic Table and Atomic Structure

The periodic table organizes elements by atomic number and properties.

• Groups: Columns with similar chemical properties.

• Periods: Rows indicating energy levels.

• Atomic Number: Number of protons in an atom.

• Atomic Mass: Sum of protons and neutrons.

Example: Carbon has atomic number 6 and atomic mass 12.

Polar Molecules

Polar molecules have regions of partial positive and negative charge due to unequal sharing of electrons.

• Example: Water (H2O) is polar because oxygen is more electronegative than hydrogen.

Ionic and Covalent Bonding

Atoms form chemical bonds to achieve stable electron configurations.

• Ionic Bonds: Formed when electrons are transferred from one atom to another, creating ions (e.g., NaCl).

• Covalent Bonds: Formed when atoms share electrons (e.g., H2O).

• Diagram: Covalent bonds are shown as lines between atoms; ionic bonds as attractions between charged ions.

Example: Sodium chloride (NaCl) is ionic; water (H2O) is covalent.

Water and Its Properties

Water is essential for life due to its unique properties.

• Cohesion: Water molecules stick together via hydrogen bonds.

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water resists temperature changes.

• Solvent: Water dissolves many substances.

Example: Water moderates Earth's climate and is the medium for biochemical reactions.

pH and Buffers

pH measures the concentration of hydrogen ions in a solution.

• pH Scale: Ranges from 0 (acidic) to 14 (basic); 7 is neutral.

• Formula: $\text{pH} = -\log_{10}[\text{H}^+]$

• Buffers: Substances that minimize changes in pH by accepting or donating H+ ions.

Example: Blood contains buffers to maintain pH near 7.4.

Chapter 3: Organic Molecules and Biological Macromolecules

Organic Molecules

Organic molecules are carbon-based compounds essential for life.

• Carbon: Can form four covalent bonds, allowing for diverse structures.

Example: Glucose (C6H12O6), DNA, proteins.

Major Biological Macromolecules

There are four major classes of biological macromolecules, each with unique structures and functions.

Macromolecule	Monomer	Function
Carbohydrates	Monosaccharides	Energy storage, structure
Lipids	Fatty acids, glycerol	Energy storage, membranes
Proteins	Amino acids	Catalysis, structure, transport
Nucleic Acids	Nucleotides	Genetic information

Polymerization

Macromolecules are formed by joining monomers through dehydration synthesis (removal of water).

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

• Hydrolysis: Breaking polymers into monomers by adding water.

Example: Starch is a polymer of glucose; proteins are polymers of amino acids.

Carbohydrates: Starch vs. Cellulose

Starch and cellulose are both polysaccharides made of glucose, but differ in structure and function.

• Starch: Energy storage in plants; digestible by humans.

• Cellulose: Structural component of plant cell walls; indigestible by humans without specific enzymes.

Example: Potatoes store starch; wood contains cellulose.

Nucleic Acids: DNA vs. RNA

DNA and RNA are nucleic acids with distinct roles in genetic information.

• DNA: Double-stranded, stores genetic information.

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

Example: DNA in chromosomes; mRNA in translation.

Lipids: Saturated vs. Unsaturated Fats

Lipids are hydrophobic molecules important for energy storage and membranes.

• Saturated Fats: No double bonds; solid at room temperature (e.g., butter).

• Unsaturated Fats: One or more double bonds; liquid at room temperature (e.g., olive oil).

Denaturation

Denaturation is the loss of a protein's native structure due to external stress (e.g., heat, pH).

Biological Impact: Denatured proteins lose function, which can affect cellular processes.

Example: Cooking an egg denatures its proteins.

Functions of Macromolecules

Each macromolecule class has specific functions essential for life.

• Carbohydrates: Energy, structure (e.g., cellulose in plants).

• Lipids: Energy storage, cell membranes, signaling.

• Proteins: Enzymes, structure, transport, defense.

• Nucleic Acids: Store and transmit genetic information.

Example: Cellulose digestion in cows is possible due to symbiotic bacteria.

Additional info: Some content (e.g., details on denaturation, cellulose digestion) is inferred from standard biology curricula, as the original guide references these topics but does not elaborate.