General Biology: Foundations, Chemistry, Water, and Organic Molecules

Chapter 1: Introduction to Biology and the Scientific Method

Key Concepts in Biology

This chapter introduces the foundational principles of biology, focusing on the scientific method, experimental design, and the characteristics of life.

• Terms: Hypothesis (a testable statement), Prediction (expected outcome), Experimental Variables (factors that can change in an experiment), Control Variables (constants), Independent Variable (manipulated factor), Dependent Variable (measured outcome), Constants/Controls (unchanged factors).

• Scientific Method: A systematic approach to inquiry involving observation, hypothesis formation, experimentation, and conclusion.

• Properties of Life: Organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation through evolution.

• Evolution: The process by which populations of organisms change over generations through mechanisms such as natural selection.

• Natural Selection: The differential survival and reproduction of individuals due to differences in phenotype.

• Adaptation: Traits that improve an organism's ability to survive and reproduce in a particular environment.

• Descent with Modification: The passing on of traits from parent organisms to their offspring, with changes over time.

Example: Charles Darwin's theory of evolution by natural selection explains how species adapt to their environments over time.

Chapter 2: Chemistry and Biology

Atoms, Elements, and the Periodic Table

This section covers the basic chemical principles underlying biological processes, including atomic structure, chemical bonds, and the periodic table.

• Terms: Element, Atom, Molecule, Compound, Subatomic Particle (proton, neutron, electron), Atomic Number (number of protons), Mass Number (protons + neutrons), Isotope (atoms with same number of protons but different neutrons).

• Atomic Mass/Weight: The weighted average mass of an atom's isotopes.

• Radioactivity: The spontaneous emission of particles or energy from unstable atomic nuclei.

• Half-life: The time required for half the atoms in a radioactive sample to decay.

• Radioactive Dating: Using isotopes to determine the age of materials.

• Energy: The capacity to do work; Kinetic Energy (energy of motion), Potential Energy (stored energy).

• Valence Shell: The outermost electron shell of an atom; determines chemical reactivity.

• Electronegativity: The tendency of an atom to attract electrons in a chemical bond.

• Ions: Atoms or molecules with a net electric charge due to loss or gain of electrons.

Example: Carbon-14 dating is used to estimate the age of ancient biological materials.

Chemical Bonds and Reactions

• Chemical Bond: The force holding atoms together in molecules; includes covalent, ionic, and hydrogen bonds.

• Covalent Bond: Atoms share electron pairs.

• 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 or nitrogen).

• Polar/Nonpolar Molecules: Polar molecules have unequal sharing of electrons; nonpolar have equal sharing.

• Van der Waals Forces: Weak attractions between molecules due to temporary dipoles.

• Chemical Reaction: The process by which substances change into different substances through the breaking and forming of bonds.

• Chemical Equilibrium: The state in which the forward and reverse reactions occur at the same rate.

Example: Water molecules are held together by hydrogen bonds, giving water its unique properties.

Chapter 3: Water and Its Properties

Properties of Water

Water is essential for life due to its unique chemical and physical properties, which arise from its molecular structure and hydrogen bonding.

• States of Water: Solid (ice), liquid, gas (vapor).

• Polarity: Water is a polar molecule, allowing it to form hydrogen bonds.

• Cohesion: Attraction between water molecules; leads to surface tension.

• Adhesion: Attraction between water molecules and other substances.

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

• Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance by 1°C.

• Evaporative Cooling: As water evaporates, it removes heat, cooling the surface.

• Density: Ice is less dense than liquid water, so it floats.

• Solvent Properties: Water dissolves many substances, making it the "universal solvent."

• Hydrophilic: Substances that dissolve in water; Hydrophobic: Substances that do not dissolve in water.

• Acids and Bases: Acids increase H+ concentration; bases decrease it. pH measures hydrogen ion concentration.

• Buffer: A substance that minimizes changes in pH.

Example: Water's high specific heat helps regulate Earth's climate and organisms' body temperatures.

Table: Properties of Water

Property	Description	Biological Importance
Cohesion	Water molecules stick together	Enables transport in plants
Adhesion	Water molecules stick to other surfaces	Helps water move up plant vessels
High Specific Heat	Resists temperature change	Stabilizes climate and body temperature
Ice Floats	Solid water is less dense than liquid	Insulates aquatic life in winter
Solvent	Dissolves many substances	Facilitates chemical reactions in cells

Chapter 4: Organic Chemistry and Biological Molecules

Carbon Chemistry and Functional Groups

Organic chemistry is the study of carbon-containing compounds, which form the basis of all living organisms. Carbon's ability to form four covalent bonds allows for a diversity of stable molecules.

• Terms: Organic Chemistry, Hydrocarbon, Functional Group, Isomer (structural, cis-trans), Carboxyl, Hydroxyl, Amino, Sulfhydryl, Phosphate, Methyl.

• Carbon Backbone: The chain or ring of carbon atoms in organic molecules.

• Functional Groups: Specific groups of atoms that confer characteristic chemical properties to molecules (e.g., hydroxyl, carboxyl, amino).

• Isomers: Molecules with the same molecular formula but different structures.

• ATP (Adenosine Triphosphate): The primary energy carrier in cells.

Example: The amino group (-NH2) is found in amino acids, the building blocks of proteins.

Table: Common Functional Groups in Biology

Functional Group	Structure	Properties
Hydroxyl	-OH	Polar, forms hydrogen bonds
Carboxyl	-COOH	Acidic, donates H+
Amino	-NH2	Basic, accepts H+
Phosphate	-PO4	Contributes negative charge, energy transfer
Methyl	-CH3	Nonpolar, affects gene expression

Additional Key Points

• Know the results of Miller's experiment, which demonstrated the abiotic synthesis of organic molecules.

• Understand the importance of ATP and how it provides energy for cellular processes.

• Recognize the significance of functional groups in determining the properties and functions of biological molecules.

Example: ATP releases energy when its phosphate bonds are broken, fueling cellular activities.