General Biology Exam Study Guide: Key Concepts and Processes

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Biology is the scientific study of life and living organisms. Understanding what constitutes life is foundational to the study of biology.

Biology: The study of living organisms and their interactions with the environment.
Characteristics of Life: Living organisms display organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation through evolution.
Levels of Biological Organization: Ranges from molecules to the biosphere, including cells, tissues, organs, organisms, populations, communities, ecosystems, and biosphere.
Structure and Function: The shape and structure of biological components are closely related to their function. Example: The structure of a bird's wing enables flight.
Unity and Diversity: All living things share common features (unity) but also exhibit diversity due to evolution.
Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.
Biological Investigation: Involves forming hypotheses, conducting experiments, and analyzing results.
Scientific Method: Steps include observation, hypothesis formation, experimentation, and conclusion.
Variables in Experiments:
- Independent Variable: The factor that is changed or manipulated.
- Dependent Variable: The factor that is measured.
- Experimental Group: Receives the treatment.
- Control Group: Used for comparison, does not receive the treatment.

Additional info: The scientific method is central to all biological research and helps ensure objectivity and reproducibility.

All matter is composed of atoms, which combine to form molecules and compounds essential for life.

Atom: The smallest unit of an element, consisting of protons, neutrons, and electrons.
Element: A substance that cannot be broken down into simpler substances by chemical means.
Molecule: Two or more atoms bonded together.
Compound: A substance formed from two or more elements in fixed proportions.
Ion: An atom or molecule with a net electric charge due to loss or gain of electrons.
Isotope: Atoms of the same element with different numbers of neutrons.
Electron Shell Model: Electrons are arranged in shells around the nucleus; the arrangement determines chemical reactivity.

Chemical bonds hold atoms together in molecules and compounds. Water's unique properties are vital for life.

Covalent Bond: Atoms share electrons.
Ionic Bond: Atoms transfer electrons, resulting in charged ions.
Hydrogen Bond: Weak attraction between a hydrogen atom and another electronegative atom.
Polar vs. Nonpolar Bonds: Polar bonds have unequal sharing of electrons; nonpolar bonds have equal sharing.
Water Molecule: H2O; exhibits polarity and forms hydrogen bonds.
Emergent Properties of Water: Cohesion, adhesion, high specific heat, solvent abilities, and ice's lower density compared to liquid water.

Water molecules interact through cohesion and adhesion, leading to surface tension and capillary action.

Cohesion: Attraction between molecules of the same substance (e.g., water molecules).
Adhesion: Attraction between molecules of different substances.
Surface Tension: The result of cohesion at the surface of a liquid.

Acids and bases affect the pH of solutions, which is crucial for biological processes.

Acid: Substance that increases hydrogen ion concentration in solution.
Base: Substance that decreases hydrogen ion concentration.
pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), with 7 as neutral.
pH Equation:
Law of Conservation of Matter: Matter cannot be created or destroyed in chemical reactions.

Organic molecules are carbon-based and form the building blocks of cells. Macromolecules include carbohydrates, proteins, lipids, and nucleic acids.

Organic Molecule: Contains carbon and is found in living organisms.
Carbohydrates: Provide energy and structural support. Examples: Glucose, starch, cellulose.
Proteins: Made of amino acids; perform structural, enzymatic, and regulatory functions.
Lipids: Include fats, phospholipids, and steroids; important for energy storage and membrane structure.
Nucleic Acids: DNA and RNA; store and transmit genetic information.
Monomer: A single subunit; polymers are chains of monomers.
Polymerization: Formation of polymers from monomers via dehydration reactions.
Hydrolysis: Breakdown of polymers into monomers by adding water.

Functional groups determine the properties and reactivity of organic molecules.

Functional Groups: Specific groups of atoms within molecules that confer particular chemical properties (e.g., hydroxyl, carboxyl, amino, phosphate).
Classification Table:

Macromolecule	Monomer	Function
Carbohydrate	Monosaccharide	Energy, structure
Protein	Amino acid	Structure, enzymes, regulation
Lipid	Fatty acid, glycerol	Energy storage, membranes
Nucleic Acid	Nucleotide	Genetic information

Additional info: The structure of each macromolecule determines its biological role.

Genetic information is stored in DNA and RNA, which direct protein synthesis. Protein structure determines function.

DNA: Double helix; stores genetic information.
RNA: Single-stranded; involved in protein synthesis.
Protein Denaturation: Loss of structure due to environmental changes, affecting function.

Cell Theory states that all living things are composed of cells, which are the basic units of life. Cells can be prokaryotic or eukaryotic.

Cell Theory: All organisms are made of cells; cells are the basic unit of life; all cells arise from pre-existing cells.
Prokaryotic Cells: Lack a nucleus and membrane-bound organelles (e.g., bacteria).
Eukaryotic Cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals, fungi).

Cells contain specialized structures (organelles) that perform distinct functions necessary for life.

Plasma Membrane: Controls entry and exit of substances.
Nucleus: Contains genetic material (DNA).
Nucleolus: Produces ribosomes.
Ribosome: Synthesizes proteins.
Smooth Endoplasmic Reticulum: Lipid synthesis and detoxification.
Rough Endoplasmic Reticulum: Protein synthesis (has ribosomes attached).
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.
Lysosome: Digests cellular waste.
Peroxisome: Breaks down fatty acids and detoxifies harmful substances.
Mitochondrion: Produces ATP via cellular respiration.
Chloroplast: Site of photosynthesis in plant cells.
Cytoskeleton: Provides structural support and facilitates movement.
Centrosome & Centrioles: Organize microtubules during cell division.
Cilia & Flagella: Enable cell movement.
Cell Wall: Provides structure and protection (in plants, fungi, and some bacteria).
Extracellular Matrix (ECM): Supports and regulates cell behavior.

Additional info: The function of each organelle is essential for cell survival and specialization.