General Biology Exam 1 Review: Key Concepts and Practice Questions

Chapter 1: Introduction to Biology

Key Concepts in Biology

Biology is the scientific study of life and living organisms. It encompasses a wide range of topics, from the molecular mechanisms within cells to the interactions of organisms with their environment.

• Biological Organization Levels: Life is organized in a hierarchical structure, from atoms and molecules to cells, tissues, organs, organisms, populations, communities, ecosystems, and the biosphere.

• Genomics vs. Proteomics: Genomics is the study of the entire genome of an organism, while proteomics focuses on the full set of proteins produced.

• Analogous vs. Homologous: Homologous structures are similar due to shared ancestry, while analogous structures have similar functions but evolved independently.

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

• Archaea, Bacteria, Eukarya: The three domains of life, distinguished by cellular structure and genetics.

• Deductive and Inductive Reasoning: Deductive reasoning starts with a general principle and deduces specific results; inductive reasoning builds generalizations from specific observations.

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

• Hypothesis, Theory, Prediction: A hypothesis is a testable statement; a theory is a well-substantiated explanation; a prediction is a logical outcome based on a hypothesis.

• Control Group: The group in an experiment that does not receive the experimental treatment, used as a baseline for comparison.

• Cell Theory: States that all living things are composed of cells, and all cells arise from pre-existing cells.

Chapter 2: Chemistry of Life

Atoms, Molecules, and Bonds

The chemistry of life is based on the properties and interactions of atoms and molecules.

• Elements and Compounds: Elements are pure substances consisting of one type of atom; compounds are substances formed from two or more elements chemically combined.

• Protons, Neutrons, Electrons: Subatomic particles; protons (+), neutrons (neutral), and electrons (-).

• Atomic Number and Mass: Atomic number is the number of protons; atomic mass is the sum of protons and neutrons.

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

• Covalent Bonds: Atoms share electron pairs. Polar covalent bonds have unequal sharing, leading to partial charges; nonpolar covalent bonds share electrons equally.

• Ionic Bonds: Formed when electrons are transferred from one atom to another, creating charged ions.

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

• Solution, Solvent, Solute: A solution is a homogeneous mixture; the solvent dissolves the solute.

• Hydrophobic vs. Hydrophilic: Hydrophobic substances repel water; hydrophilic substances attract water.

Chapter 3: Carbon and the Molecular Diversity of Life

Organic Molecules and Functional Groups

Carbon's ability to form four covalent bonds makes it the backbone of organic molecules, leading to a diversity of life forms.

• Functional Groups: Specific groups of atoms within molecules that have characteristic properties (e.g., hydroxyl, carboxyl, amino, phosphate).

• Polymers and Monomers: Polymers are large molecules made from repeating monomers (e.g., proteins from amino acids, nucleic acids from nucleotides).

• Dehydration Synthesis and Hydrolysis: Dehydration synthesis joins monomers by removing water; hydrolysis breaks polymers by adding water.

• Carbohydrates, Proteins, Nucleic Acids, Lipids: The four major classes of biological macromolecules, each with distinct structures and functions.

• Phospholipids: Major components of cell membranes, consisting of hydrophilic heads and hydrophobic tails.

Chapter 4: Cell Structure and Function

Prokaryotic and Eukaryotic Cells

Cells are the basic units of life, classified as prokaryotic or eukaryotic based on their structure.

• Prokaryotes vs. Eukaryotes: Prokaryotes (Bacteria and Archaea) lack a nucleus; eukaryotes (plants, animals, fungi, protists) have a nucleus and membrane-bound organelles.

• Cell Membrane: A phospholipid bilayer that controls the movement of substances in and out of the cell.

• Organelles: Specialized structures within eukaryotic cells (e.g., nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes).

• Cell Wall: Provides structural support in plants, fungi, and some prokaryotes.

• Plasma Membrane Permeability: Selectively allows certain molecules to pass through.

• Concentration Gradient: Difference in concentration of a substance across a space or membrane.

Chapter 5: Membrane Structure and Function

Transport Across Membranes

Cell membranes regulate the movement of substances, maintaining homeostasis.

• Fluid Mosaic Model: Describes the structure of cell membranes as a mosaic of components (phospholipids, proteins, cholesterol) that move fluidly.

• Passive Transport: Movement of substances across membranes without energy input (e.g., diffusion, osmosis, facilitated diffusion).

• Active Transport: Movement of substances against their concentration gradient, requiring energy (usually ATP).

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Facilitated Diffusion: Passive movement of molecules via transport proteins.

• Endocytosis and Exocytosis: Processes for bulk transport of materials into (endocytosis) or out of (exocytosis) the cell.

Practice Questions and Reasoning

Scientific Reasoning and Experimental Design

• Deductive Reasoning: Drawing specific conclusions from general principles. Example: "All students who sleep 8 hours do well; you sleep 8 hours; therefore, you will do well."

• Experimental Controls: Positive control is a group expected to show a response; negative control is not expected to show a response. Independent variable is manipulated; dependent variable is measured.

• Example Table: Types of Experimental Variables

Term	Definition	Example
Independent Variable	The factor that is changed or controlled in an experiment	Type of medicine given
Dependent Variable	The factor that is measured or observed	Hours of sleep
Control Group	Group not receiving the experimental treatment	Placebo group
Positive Control	Group expected to show a positive result	Group receiving known effective treatment
Negative Control	Group expected to show no effect	Group receiving placebo

Sample Multiple Choice Questions

• Reasoning Types: Deductive, cumulative, inductive, incomplete reasoning.

• Experimental Design: Identifying positive controls, negative controls, and variables in a study.

Key Equations and Concepts

• Concentration Gradient: Drives diffusion and osmosis.

• Osmosis Equation:

$J = -P (C_2 - C_1)$ Where $J$ is the flux, $P$ is the permeability coefficient, and $C_2 - C_1$ is the concentration difference across the membrane.

• ATP Hydrolysis (energy for active transport):

$ATP + H_2O \rightarrow ADP + P_i + \text{energy}$

Additional info: Some explanations and examples have been expanded for clarity and completeness based on standard General Biology curricula.