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, variables, and the characteristics of life.

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

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

• Experiment: A controlled procedure to test a hypothesis.

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

Evolution and Natural Selection

• Charles Darwin: Developed the theory of evolution by natural selection, explaining how species adapt and change over time.

• Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.

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

• Descent with Modification: The passing of traits from parent to offspring, with changes accumulating over generations.

• Unity and Diversity: All living things share common characteristics but also exhibit diversity due to evolutionary processes.

Example: Darwin's finches on the Galápagos Islands evolved different beak shapes to exploit different food sources.

Chapter 2: Basic Chemistry for Biology

Atoms, Elements, and Molecules

This section covers the chemical basis of life, including atomic structure, elements, and chemical bonds.

• Atom: The smallest unit of matter retaining the properties of an element.

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

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

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

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

• Electron Shells: Energy levels where electrons are found; determine chemical reactivity.

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

Chemical Bonds and Reactions

• 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 or nitrogen).

• Chemical Reaction: Process that changes substances into different substances by breaking and forming bonds.

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

Example: Water (H2O) forms when two hydrogen atoms covalently bond with one oxygen atom.

Additional info: Scientists use isotopes in medicine (e.g., PET scans) and to date ancient biological materials (e.g., carbon dating).

Chapter 3: Water and Its Properties

Structure and Properties of Water

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

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

• Polarity: Water is a polar molecule, with partial positive and negative charges, leading to hydrogen bonding.

• Cohesion: Attraction between water molecules; responsible for 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: Amount of heat needed to raise the temperature of 1 gram of a substance by 1°C.

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

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

• Buffer: Substance that minimizes changes in pH.

Importance of Water for Life

• Water moderates Earth's temperature and supports all known forms of life.

• Water's high specific heat helps organisms maintain stable internal temperatures.

• Ice floats because it is less dense than liquid water, insulating aquatic life in winter.

• Water is an excellent solvent, dissolving many substances necessary for life.

Example: Capillary action allows water to move up plant stems against gravity.

Table: Comparison of Water's Properties

Chapter 4: Organic Molecules and Carbon Chemistry

Carbon: The Backbone of Life

Carbon's unique properties allow it to form a variety of complex molecules essential for life.

• Organic Chemistry: Study of carbon-containing compounds.

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

• Cis-Trans Isomers: Differ in arrangement around a double bond.

• Functional Groups: Specific groups of atoms that confer particular properties to molecules (e.g., hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, methyl).

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

Biological Molecules and Their Functions

• Hydrocarbons: Compounds composed only of carbon and hydrogen; nonpolar and hydrophobic.

• Enzymes: Biological catalysts that speed up chemical reactions.

• Macromolecules: Large molecules such as proteins, nucleic acids, carbohydrates, and lipids.

• Functional Groups in Biology: Affect molecular behavior and interactions (e.g., amino group in amino acids).

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

Additional info: Stanley Miller's experiment demonstrated that organic molecules could form under prebiotic Earth conditions, supporting theories about the origin of life.

Table: Common Functional Groups in Organic Molecules

Key Equations

• Calculating Atomic Mass:

• Calculating Moles:

• Energy in ATP Hydrolysis: