The approximate distribution of questions by content category is shown below.

I. CELLULAR AND MOLECULAR BIOLOGY— 33-34%

• Fundamentals of cellular biology, genetics, and molecular biology are addressed.
• Major topics in cellular structure and function include metabolic pathways and their regulation, membrane dynamics, cell surfaces, organelles, cytoskeleton, and cell cycle.
• Major areas in genetics and molecular biology include chromatin and chromosomal structure, genomic organization and maintenance, and the regulation of gene expression.
• The cellular basis of immunity, the mechanisms of antigen-antibody interactions, and cell-pathogen interactions are included.
• Distinctions between prokaryotic and eukaryotic cells are considered where appropriate.
• Attention is also given to experimental methodology.

A. Cellular Structure and Function — 16-17%

1. Biological compounds

• Macromolecular structure and bonding
• Abiotic origin of biological molecules

2. Enzyme activity, receptor binding, and regulation

3. Major metabolic pathways and regulation

• Respiration, fermentation, and photosynthesis
• Synthesis and degradation of macromolecules
• Hormonal control and intracellular messengers

4. Membrane dynamics and cell surfaces

• Transport, endocytosis, and exocytosis
• Electrical potentials and neurotransmitters
• Mechanisms of cell recognition, cell junctions, and plasmodesmata
• Cell wall and extracellular matrix

5. Organelles: structure, function, and targeting

6. Cytoskeleton, motility, and shape

• Actin-based systems
• Microtubule-based systems
• Intermediate filaments
• Bacterial flagella and movement

7. Cell cycle, growth, division, and regulation

B. Genetics and Molecular Biology — 16-17%

1. Genetic foundations

• Mendelian inheritance; Pedigree analysis
• Prokaryotic genetics (transformation, transduction, and conjugation)
• Genetic mapping

2. Chromatin and chromosomes

• Nucleosomes
• Karyotypes
• Chromosomal aberrations
• Polytene chromosomes

3. Genome sequence organization

• Introns and exons; Single-copy and repetitive DNA
• Transposable elements

4. Genome maintenance

• DNA replication; DNA mutation and repair

5. Gene expression and regulation in prokaryotes and eukaryotes: mechanisms

• The operon; Promoters and enhancers; Transcription factors; RNA and protein synthesis; Processing and modifications of both RNA and protein

6. Gene expression and regulation: effects

• Control of normal development; Cancer and oncogenes
• Signaling mechanisms in cells

7. Immunobiology

• Cellular basis of immunity; Antibody diversity and synthesis
• Antigen-antibody interactions

8. Bacteriophages, animal viruses, and plant viruses

• Viral genomes, replication, and assembly
• Virus-host cell interactions

9. Recombinant DNA methodology

• Restriction endonucleases; Blotting and hybridization
• Restriction fragment length polymorphisms;
• DNA cloning, sequencing, and analysis;
• Polymerase chain reaction

II. ORGANISMAL BIOLOGY— 33-34%

• The structure, physiology, behavior, and development of plants and animals are addressed.
• Topics covered include nutrient procurement and processing, gas exchange, internal transport, regulation of fluids, control mechanisms and effectors, and reproduction in autotrophic and heterotrophic organisms. 
• Examples of developmental phenomena range from fertilization through differentiation and morphogenesis.
• Perceptions and responses to environmental stimuli are examined as they pertain to both plants and animals.
• Major distinguishing characteristics and phylogenetic relationships of selected groups from the various kingdoms are also covered.

A. Animal Structure, Function, and Organization — 9-10%

1. Exchange with environment

• Nutrient, salt, and water exchange
• Gas exchange; Energy

2. Internal transport and exchange

• Circulatory, gastrovascular, and digestive systems

3. Support and movement

• Support systems (external, internal, and hydrostatic)
• Movement systems (flagellar, ciliary, and muscular)

4. Integration and control mechanisms

• Nervous and endocrine systems

5. Behavior (communication, orientation, learning, and instinct)

6. Metabolic rates (temperature, body size, and activity)

B. Animal Reproduction and Development — 5-6%

1. Reproductive structures

2. Meiosis, gametogenesis, and fertilization

3. Early development (e.g., polarity, cleavage, and gastrulation)

4. Developmental processes (e.g., induction, determination, differentiation, morphogenesis, and metamorphosis)

5. External control mechanisms (e.g., photoperiod)

C. Plant Structure, Function, and Organization, with Emphasis on Flowering Plants — 6-7%

1. Tissues, tissue systems, and organs

2. Water transport, including absorption and transpiration

3. Phloem transport and storage

4. Mineral nutrition

5. Plant energetics (e.g., respiration and photosynthesis)

D. Plant Reproduction, Growth, and Development, with Emphasis on Flowering Plants — 4-5%

1. Reproductive structures

2. Meiosis and sporogenesis

3. Gametogenesis and fertilization

4. Embryogeny and seed development

5. Meristems, growth, morphogenesis, and differentiation

6. Control mechanisms (e.g., hormones, photoperiod, and tropisms)

E. Diversity of Life — 6-7%

1. Archaebacteria Morphology, physiology, and identification

2. Eubacteria (including cyanobacteria)

• Morphology, physiology, pathology, and identification

3. Protista

• Protozoa, other heterotrophic Protista (slime molds and Oomycota), and autotrophic Protista
  
  Major distinguishing characteristics
  Phylogenetic relationships
  Importance (e.g., eutrophication, disease)

4. Fungi

• Distinctive features of major phyla (vegetative, asexual, and sexual reproduction)
• Generalized life cycles
• Importance (e.g., decomposition, biodegradation, antibiotics, and pathogenicity)
• Lichens

5. Animalia with emphasis on major phyla

• Major distinguishing characteristics
• Phylogenetic relationships

6. Plantae with emphasis on major phyla

• Alternation of generations
• Major distinguishing characteristics
• Phylogenetic relationships

III. Ecology and Evolution— 33-34%

• Interactions of organisms and their environment, emphasizing biological principles at levels above the individual.
• Ecological and evolutionary topics are given equal weight.
• Ecological questions range from physiological adaptations to the functioning of ecosystems.
• Although principles are emphasized, some questions may consider applications to current environmental problems.
• Questions in evolution range from its genetic foundations through evolutionary processes to their consequences.
• Evolution is considered at the molecular, individual, population, and higher levels.
• Principles of ecology, genetics, and evolution are interrelated in many questions.
• Some questions may require quantitative skills, including the interpretation of simple mathematical models.

A. Ecology — 16-17%

1. Environment/organism interaction

• Biogeographic patterns; Adaptations to environment; Temporal patterns

2. Behavioral ecology

• Habitat selection; Mating systems; Social systems; Resource acquisition

3. Population structure and function

• Population dynamics/regulation; Demography and life history strategies

4. Communities

• Interspecific relationships; Community structure and diversity; Change and succession

5. Ecosystems

• Productivity and energy flow; Chemical cycling

B. Evolution — 16-17%

1. Genetic variability

• Origins (mutations, linkage, recombination, and chromosomal alterations)
• Levels (e.g., polymorphism and heritability)
• Spatial patterns (e.g., clines and ecotypes)
• Hardy-Weinberg equilibrium

2. Evolutionary processes

• Gene flow and genetic drift; Natural selection; Levels of selection (e.g., individual and group)

3. Evolutionary consequences

• Fitness and adaptation; Speciation; Systematics and phylogeny; Convergence, divergence, and extinction

4. History of life

• Origin of prokaryotic and eukaryotic cells
• Fossil record

Paleontology and paleoecology