General Biology: Foundational Concepts and Review Questions (Ch. 1–4)

Ch. 1 – An Introduction to Life on Earth

Scientific Method and Experimental Design

The scientific method is a systematic approach to understanding natural phenomena through observation, hypothesis formation, experimentation, and analysis.

• Controlled Experiments: Involve manipulating one variable while keeping others constant to determine its effect.

• Variables: Independent (manipulated), dependent (measured), and controlled (kept constant).

• Example: Testing the effect of vitamin D on rat growth by comparing groups with and without vitamin D under identical conditions.

Additional info: A good experiment should minimize the number of variables to isolate the effect of the independent variable.

Autotrophs and Heterotrophs

Organisms are classified based on how they obtain energy and nutrients.

• Autotrophs: Produce their own food from inorganic sources (e.g., photosynthetic bacteria).

• Heterotrophs: Obtain energy by consuming other organisms.

Natural Selection and Evolution

Natural selection is the process by which individuals with advantageous traits survive and reproduce more successfully.

• Variation: Exists among individuals in a population.

• Selection: Favors traits that enhance survival and reproduction.

Ch. 2 – Atoms, Molecules, and Life

Atomic Structure and Chemical Bonds

Atoms are the basic units of matter, composed of protons, neutrons, and electrons.

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

• Covalent Bonds: Formed by the sharing of electron pairs between atoms.

• Example: A single covalent bond involves the sharing of two electrons.

Water and Its Properties

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

• Cohesion: Water molecules stick to each other via hydrogen bonds.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water resists temperature changes.

• Solvent Properties: Water dissolves many substances due to its polarity.

Acids, Bases, and Buffers

Acids and bases affect the pH of solutions, while buffers help maintain pH stability.

• Acids: Substances that release H+ ions.

• Bases: Substances that accept H+ ions or release OH- ions.

• Buffers: Substances that stabilize pH by accepting or releasing H+.

Radioactive Isotopes and Dating

Radioactive isotopes decay at predictable rates and are used in dating fossils and rocks.

• Carbon-14 Dating: Used to determine the age of formerly living materials.

• Equation: $N = N_0 e^{-\lambda t}$ (where $N$ is the number of radioactive atoms remaining, $N_0$ is the initial number, $\lambda$ is the decay constant, and $t$ is time)

Ch. 3 – Biological Molecules

Types of Biological Molecules

Biological molecules are essential for structure and function in living organisms.

• Carbohydrates: Provide energy and structural support.

• Lipids: Store energy and make up cell membranes.

• Proteins: Serve as enzymes, structural components, and signaling molecules.

• Nucleic Acids: Store and transmit genetic information (DNA, RNA).

Polymers and Monomers

Large biological molecules (polymers) are synthesized by joining smaller units (monomers).

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Examples and Functions

• Starch: Storage form of glucose in plants.

• Glycogen: Storage form of glucose in animals.

• Cellulose: Structural component in plant cell walls.

Ch. 4 – Cell Structure and Function

Prokaryotic vs. Eukaryotic Cells

Cells are classified as prokaryotic or eukaryotic based on their structure.

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles.

• Eukaryotic Cells: Have a nucleus and various organelles (e.g., mitochondria, endoplasmic reticulum).

Cell Organelles and Their Functions

• Nucleus: Contains genetic material (DNA).

• Rough Endoplasmic Reticulum (ER): Synthesizes proteins with attached ribosomes.

• Golgi Apparatus: Packages and modifies proteins.

• Mitochondria: Site of aerobic respiration and ATP production.

• Plastids: In plants, involved in photosynthesis and storage.

Cell Membranes and Transport

Cell membranes regulate the movement of substances in and out of cells.

• Phospholipid Bilayer: Provides structural integrity and selective permeability.

• Transport Proteins: Facilitate movement of molecules across membranes.

Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic Cell	Eukaryotic Cell
Nucleus	Absent	Present
Membrane-bound Organelles	Absent	Present
Size	Smaller	Larger
Examples	Bacteria, Archaea	Plants, Animals, Fungi

Additional info:

These foundational concepts are essential for understanding subsequent chapters in General Biology, including cell processes, genetics, and evolution.