Honors Biology Final Exam Review: Cell Division, Genetics, Evolution, and Body Systems

Cell Division

Stages of the Cell Cycle

• G1 Phase (Gap 1): Cell grows, carries out normal functions, and prepares for DNA replication.

• S Phase (Synthesis): DNA is replicated, resulting in two identical sets of chromosomes.

• G2 Phase (Gap 2): Further cell growth and preparation for mitosis; organelles may duplicate.

• M Phase (Mitosis): Division of the nucleus and cytoplasm (cytokinesis) to form two daughter cells.

• G0 Phase: Resting phase where cells exit the cycle and do not divide (e.g., nerve cells).

Regulation of the Cell Cycle

• Controlled by checkpoints (G1, G2, M) and regulatory proteins (cyclins, CDKs).

• Unregulated cell division can lead to cancer, where cells divide uncontrollably.

Mitosis: Stages and Events

• Prophase: Chromosomes condense, spindle fibers form, nuclear envelope breaks down.

• Metaphase: Chromosomes align at the cell's equator.

• Anaphase: Sister chromatids separate and move to opposite poles.

• Telophase: Nuclear envelopes reform, chromosomes decondense.

• Cytokinesis: Division of the cytoplasm, forming two daughter cells.

Meiosis: Stages and Events

• Meiosis I: Homologous chromosomes separate (reductional division).

• Meiosis II: Sister chromatids separate (similar to mitosis).

• Produces four haploid gametes (sperm or eggs).

Comparison: Mitosis vs. Meiosis

Feature	Mitosis	Meiosis
Number of Divisions	1	2
Daughter Cells	2 (diploid)	4 (haploid)
Purpose	Growth, repair	Gamete production
Types of Cells Produced	Somatic	Gametes

Genetic Variation

• Meiosis and fertilization increase genetic diversity via crossing over, independent assortment, and random fusion of gametes.

Genetics

Key Terminology

• Homozygous: Two identical alleles for a gene (e.g., AA or aa).

• Heterozygous: Two different alleles (e.g., Aa).

• Dominant/Recessive: Dominant alleles mask recessive ones in heterozygotes.

• Pedigree: Diagram showing inheritance patterns in families.

• Monohybrid/Dihybrid: Crosses involving one or two traits, respectively.

• F1/F2 Generations: First and second filial generations in genetic crosses.

Solving Genetic Crosses

• Use Punnett squares to predict offspring genotypes and phenotypes.

• Dihybrid crosses involve two traits; typical ratio for heterozygotes is 9:3:3:1.

• X-linked traits are found on sex chromosomes; males are more affected by recessive X-linked disorders.

• Linked genes are inherited together unless crossing over occurs.

• Blood types are determined by multiple alleles (A, B, O) and codominance.

Genetic Engineering

• Involves inserting human genes into bacteria to produce proteins (e.g., insulin).

Genetic Diseases and Mutations

• Mutations can alter protein function, leading to genetic diseases.

Gel Electrophoresis

• Separates DNA fragments by size using an electric field; used in DNA fingerprinting.

Karyotypes and Chromosomal Abnormalities

• Karyotype: Visual display of chromosomes; used to detect abnormalities (e.g., Down syndrome from nondisjunction).

Pedigree Charts

• Show inheritance of traits; can distinguish between dominant/recessive and X-linked/autosomal disorders.

Origin of Life and Evolution

Species and Evolution

• Species: Group of organisms that can interbreed and produce fertile offspring.

• Evolution in Bacteria: Seen in antibiotic resistance due to natural selection.

Evidence for Evolution

• Fossil record, comparative anatomy, molecular biology, and observed evolutionary changes.

Natural Selection

• Process where organisms with advantageous traits survive and reproduce more successfully.

Microevolution

• Small-scale changes in allele frequencies within a population.

• Causes: mutation, gene flow, genetic drift, natural selection.

Hardy-Weinberg Equilibrium

• Describes a non-evolving population; requires no mutation, migration, selection, random mating, and large population size.

Cladograms and Phylogenetic Trees

• Show evolutionary relationships among species.

Ecosystems

Productivity and Biomass

• Productivity: Rate at which producers convert energy into biomass.

• Higher productivity supports more biomass and higher trophic levels.

Trophic Levels and Food Webs

• Producers, primary consumers, secondary consumers, etc.

Pyramids of Energy and Biomass

• Show energy or biomass at each trophic level; energy decreases up the pyramid.

Keystone Species

• Species with a disproportionately large effect on ecosystem structure.

Community Interactions

• Predation: One organism eats another.

• Competition: Organisms vie for the same resource.

• Symbiosis: Close relationships between species:

  • Mutualism: Both benefit.

  • Commensalism: One benefits, other unaffected.

  • Parasitism: One benefits, other harmed.

Cardiovascular System

Path of Blood Flow

• Blood flows: body → right atrium → right ventricle → lungs (oxygenated) → left atrium → left ventricle → body.

Oxygenation of Blood

• Blood is oxygenated in the lungs and deoxygenated in the body tissues.

Blood Vessels

• Arteries: Carry blood away from the heart (usually oxygenated).

• Veins: Carry blood toward the heart (usually deoxygenated).

• Capillaries: Site of exchange between blood and tissues.

• Valves: Prevent backflow of blood in veins and heart.

Components of Blood

• Red blood cells: Carry oxygen.

• White blood cells: Immune defense.

• Platelets: Blood clotting.

• Plasma: Liquid component, transports nutrients and waste.

Respiratory System

Structures

• Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli.

Mechanism of Breathing

• Inhalation: Diaphragm contracts, thoracic cavity expands, air enters lungs.

• Exhalation: Diaphragm relaxes, thoracic cavity decreases, air exits lungs.

Gas Exchange

• Occurs in alveoli (lungs) and at tissues; oxygen diffuses into blood, carbon dioxide diffuses out.

Nervous System

Types of Neurons

• Sensory neurons: Carry signals from receptors to CNS.

• Motor neurons: Carry signals from CNS to effectors (muscles/glands).

• Interneurons: Connect neurons within CNS.

Parts of the Brain

• Pons: Relays signals, regulates sleep and breathing.

• Medulla oblongata: Controls vital functions (heart rate, breathing).

• Cerebellum: Coordinates movement and balance.

• Cerebrum: Higher brain functions; divided into lobes (frontal, parietal, temporal, occipital).

Structure of Myelinated Neurons

• Dendrites: Receive signals.

• Cell body: Contains nucleus.

• Myelin sheath: Insulates axon, speeds up signal transmission.

• Synaptic terminal: Releases neurotransmitters.

• Axon: Conducts impulses away from cell body.

Reflexes

• Automatic responses to stimuli; involve sensory and motor neurons, sometimes bypassing the brain.

Action Potentials

• Generated by movement of ions across neuron membrane; propagated along axon.

Neurotransmitters

• Chemicals that transmit signals across synapses between neurons.

Immune System

Lymph vs. Blood Vessels

• Lymph vessels: Transport lymph, part of immune system.

• Blood vessels: Transport blood, part of circulatory system.

Lymphatic System Function

• Returns fluid to blood, filters pathogens, houses immune cells.

Components of Blood (Immune Function)

• White blood cells: Defend against pathogens.

Innate vs. Adaptive Immunity

Feature	Innate Immunity	Adaptive Immunity
Response Time	Immediate	Slower (days)
Specificity	Non-specific	Specific to pathogens
Memory	None	Has memory

B Lymphocytes vs. T Lymphocytes

• B cells: Produce antibodies, mediate humoral immunity.

• T cells: Kill infected cells, regulate immune response (cell-mediated immunity).

Inflammation

• Response to injury/infection; increases blood flow, recruits immune cells.

Antibodies

• Proteins that bind specific antigens to neutralize pathogens.

Vaccines

• Stimulate immune system to develop memory cells without causing disease.

Additional info: Where the original notes were brief, academic context and definitions have been added for clarity and completeness.