General Biology Exam Study Guide: Key Concepts and Processes

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A. Scientific Process and General Chemistry

1. Scientific Process

The scientific process is a systematic method for investigating natural phenomena. It involves observation, hypothesis formation, experimentation, data analysis, and conclusion.

Observation: Gathering information about the natural world.
Hypothesis: A testable explanation for an observation.
Experimentation: Testing the hypothesis under controlled conditions.
Data Analysis: Interpreting results to support or refute the hypothesis.
Conclusion: Drawing inferences based on data; may lead to new hypotheses.

2. Types of Chemical Bonds

Chemical bonds are forces that hold atoms together in molecules and compounds.

Ionic Bonds: Transfer of electrons between atoms, forming charged ions (e.g., NaCl).
Covalent Bonds: Sharing of electron pairs between atoms (e.g., H2O).
Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom (e.g., between water molecules).

3. Properties of Water; pH

Water is essential for life due to its unique properties.

Cohesion and Adhesion: Water molecules stick to each other and to other surfaces.
High Specific Heat: Water resists temperature changes.
Solvent Abilities: Water dissolves many substances.
pH: Measures hydrogen ion concentration;

B. Organic Chemistry

1. Major Functional Groups

Functional groups are specific groups of atoms within molecules that determine chemical properties.

Hydroxyl (-OH): Found in alcohols.
Carboxyl (-COOH): Found in acids.
Amino (-NH2): Found in amino acids.
Phosphate (-PO4): Found in nucleotides.
Sulfhydryl (-SH): Found in some amino acids.
Carbonyl (C=O): Found in ketones and aldehydes.

2. Structure, Functions, and Examples of Macromolecules

Macromolecules are large biological molecules essential for life.

Carbohydrates: Energy storage and structure; monomer is monosaccharide (e.g., glucose).
Lipids: Energy storage, membranes; monomer is fatty acid (e.g., triglycerides).
Proteins: Catalysis, structure, transport; monomer is amino acid (e.g., enzymes).
Nucleic Acids: Information storage; monomer is nucleotide (e.g., DNA, RNA).

C. Cell Parts

1. Prokaryote vs. Eukaryote

Cells are classified as prokaryotic or eukaryotic based on their structure.

Feature	Prokaryote	Eukaryote
Nucleus	Absent	Present
Organelles	Few	Many
Examples	Bacteria, Archaea	Plants, Animals, Fungi

2. Organelles; Functions; Plants vs. Animals

Organelles are specialized structures within eukaryotic cells.

Nucleus: Contains genetic material.
Mitochondria: Site of cellular respiration.
Chloroplasts: Site of photosynthesis (plants only).
Cell Wall: Provides structure (plants only).
Lysosomes: Digestion (animals only).

D. Transport

1. Types of Transport In and Out of the Cell

Cells regulate movement of substances across membranes.

Passive Transport: No energy required; includes diffusion and osmosis.
Active Transport: Requires energy (ATP); moves substances against concentration gradient.
Facilitated Diffusion: Uses transport proteins for movement.

2. Hypotonic, Isotonic, and Hypertonic

These terms describe the relative concentration of solutes in solutions.

Hypotonic: Lower solute concentration outside the cell; water enters cell.
Isotonic: Equal solute concentration; no net water movement.
Hypertonic: Higher solute concentration outside; water leaves cell.

E. Enzymes & Metabolism

1. How an Enzyme Works

Enzymes are biological catalysts that speed up chemical reactions.

Active Site: Region where substrate binds.
Lower Activation Energy: Enzymes reduce the energy needed for reactions.
Specificity: Each enzyme acts on specific substrates.

2. Structure and Importance of ATP

ATP (adenosine triphosphate) is the main energy currency of the cell.

Structure: Adenine, ribose, and three phosphate groups.
Function: Provides energy for cellular processes.
Hydrolysis: Releases energy:

F. Cellular Respiration

1. Presence and Absence of Oxygen

Cellular respiration can be aerobic (with oxygen) or anaerobic (without oxygen).

Aerobic Respiration: Produces more ATP; includes glycolysis, Krebs cycle, and electron transport chain.
Anaerobic Respiration: Produces less ATP; includes glycolysis and fermentation.

2. ATP Production via ETC and Chemiosmosis

The electron transport chain (ETC) and chemiosmosis generate ATP.

ETC: Electrons pass through protein complexes, pumping protons.
Chemiosmosis: Protons flow back through ATP synthase, producing ATP.
Equation:

G. Photosynthesis

1. Light Reactions vs. Calvin Cycle

Photosynthesis consists of two main stages.

Stage	Main Events	Location
Light Reactions	Convert light energy to chemical energy (ATP, NADPH)	Thylakoid membrane
Calvin Cycle	Uses ATP and NADPH to fix CO2 into sugars	Stroma

2. Main Products of Photosynthesis

Glucose (C6H12O6): Main energy storage molecule.
Oxygen (O2): Byproduct released into atmosphere.

H. Cell Cycle

1. Stages and Control of the Cell Cycle

The cell cycle is a series of events leading to cell division.

Stages: G1, S, G2, M (mitosis).
Checkpoints: Control progression and ensure accuracy.

2. Animal vs. Plant Mitosis

Animal Cells: Use cleavage furrow for cytokinesis.
Plant Cells: Form a cell plate during cytokinesis.

I. Meiosis

1. Importance of Crossing-Over

Crossing-over increases genetic diversity by exchanging DNA between homologous chromosomes during meiosis I.

2. Stages of Meiosis

Meiosis I: Homologous chromosomes separate.
Meiosis II: Sister chromatids separate.

3. Gametogenesis in Humans

Process	Location	End Result
Spermatogenesis	Testes	4 sperm cells
Oogenesis	Ovaries	1 egg cell, 3 polar bodies

J. Genetics

1. Mendel’s Laws

Law of Segregation: Each organism has two alleles for each gene, which separate during gamete formation.
Law of Independent Assortment: Genes for different traits assort independently.

2. Exceptions to Mendelian Inheritance

Incomplete Dominance: Heterozygotes show intermediate phenotype.
Codominance: Both alleles are expressed.
Multiple Alleles: More than two alleles exist for a gene.
Polygenic Inheritance: Multiple genes affect a trait.

3. Solving Genetic Problems

Use Punnett squares to predict genotype and phenotype ratios.
Apply probability rules for complex crosses.

K. Molecular Biology

1. DNA Replication

DNA replication is the process of copying genetic material before cell division.

Semiconservative: Each new DNA molecule has one old and one new strand.
Enzymes: DNA polymerase, helicase, primase.

2. Transcription and Translation

Transcription: DNA is copied into mRNA.
Translation: mRNA is decoded to build proteins.

3. Regulation of Eukaryotic Genes

Promoters and Enhancers: Control gene expression.
Epigenetic Modifications: DNA methylation, histone modification.

4. Modern Molecular Biology Techniques and Biotechnology

PCR (Polymerase Chain Reaction): Amplifies DNA.
Gel Electrophoresis: Separates DNA fragments.
CRISPR: Genome editing.

L. Evolution

1. Theories of Descent with Modification, History of Life, Speciation

Descent with Modification: Species change over time, giving rise to new species.
Speciation: Formation of new species through evolutionary processes.
History of Life: Fossil record and phylogenetic trees trace evolutionary history.

2. Proof of Natural Selection

Observation: Variation exists in populations.
Mechanism: Individuals with advantageous traits survive and reproduce.
Evidence: Fossils, comparative anatomy, molecular biology.

3. Mechanism for Evolution

Mutation: Source of genetic variation.
Gene Flow: Movement of genes between populations.
Genetic Drift: Random changes in allele frequencies.
Natural Selection: Differential survival and reproduction.

4. Change Driven by Natural Selection

Populations adapt to their environment over generations.
Traits that increase fitness become more common.