Chapter 1: Scientific Method and Properties of Life

Key Concepts in Scientific Inquiry

The scientific method is a systematic approach used to investigate natural phenomena. Understanding its steps and related terminology is essential for biological studies.

• Terms: Hypothesis (a testable statement), Prediction (expected outcome), Experimental Variables (factors changed or measured), Control Variables (constants), Independent Variable (manipulated), Dependent Variable (measured).

• Experiment: A controlled procedure to test a hypothesis.

• Graphing: Independent variable on x-axis, dependent variable on y-axis.

Properties of Life and Evolution

Life is characterized by organization, metabolism, responsiveness, growth, reproduction, and adaptation. Evolution explains the diversity and unity among organisms.

• Natural Selection: Process by which organisms better adapted to their environment tend to survive and reproduce.

• Adaptation: Traits that improve survival and reproduction.

• Charles Darwin: Developed the theory of evolution by natural selection.

• Descent with Modification: Passing traits from parent to offspring with changes over generations.

Example: Darwin's finches on the Galápagos Islands show adaptation in beak shape for different food sources.

Chapter 2: Chemistry for Biology

Atoms, Elements, and Chemical Bonds

Understanding atomic structure and chemical bonding is fundamental to biology. Elements are defined by their atomic number and are represented by chemical symbols.

• Atom: Smallest unit of matter retaining properties of an element.

• Element: Substance consisting of one type of atom.

• 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 Isotope: Unstable isotope that emits radiation.

• Valence Shell: Outermost electron shell; determines chemical reactivity.

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

• Cation: Positively charged ion.

• Anion: Negatively charged ion.

Chemical Bonds and Reactions

Chemical bonds form between atoms to create molecules. The main types are ionic, covalent, and hydrogen bonds.

• Ionic Bond: Transfer of electrons from one atom to another.

• Covalent Bond: Sharing of electron pairs between atoms.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom.

• Chemical Reaction: Process that changes substances into new ones.

• Chemical Equilibrium: State where forward and reverse reactions occur at equal rates.

Example: Water (H2O) forms via covalent bonds between hydrogen and oxygen; hydrogen bonds between water molecules give water its unique properties.

Table: Types of Chemical Bonds

Chapter 3: Water and Its Properties

Importance and Properties of Water

Water is essential for life due to its unique chemical and physical properties. It exists in three states: solid, liquid, and gas.

• Polarity: Water is a polar molecule with partial positive and negative charges.

• Cohesion: Water molecules stick together via hydrogen bonds.

• Adhesion: Water molecules stick to other surfaces.

• Surface Tension: Cohesion at the surface of water creates a 'skin'.

• Specific Heat: Amount of heat needed to change water's temperature; water has a high specific heat.

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

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

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

• pH: Measure of hydrogen ion concentration; water is neutral at pH 7.

• Buffer: Substance that minimizes changes in pH.

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

Table: Physical States and Properties of Water

Chapter 4: Organic Molecules and Carbon Chemistry

Carbon and Organic Compounds

Carbon is the backbone of organic molecules, capable of forming complex structures. Organic chemistry studies carbon-containing compounds.

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

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

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

• ATP (Adenosine Triphosphate): Main energy currency of the cell.

• Enzymes: Biological catalysts important in medicine and metabolism.

Example: Miller-Urey experiment demonstrated that organic molecules could form under prebiotic conditions.

Table: Common Functional Groups in Organic Molecules

ATP and Energy in Cells

ATP stores and releases energy for cellular processes. Its hydrolysis provides energy for metabolism.

• ATP Structure: Adenine base, ribose sugar, three phosphate groups.

• ATP Hydrolysis: Releases energy by breaking the terminal phosphate bond.

Equation:

Additional info: Scientists use radioactive isotopes for dating fossils and medical imaging. Ocean acidification is caused by increased CO2 dissolving in seawater, forming carbonic acid and lowering pH.