• The test contains about 200 five-choice questions, a number of which are grouped in sets toward the end of the test and are based on descriptions of laboratory and field situations, diagrams, or experimental results.
• The content of the test is organized into three major areas: cellular and molecular biology, organismal biology, and ecology and evolution. Approximately equal weight is given to each of these three areas. In addition to the total score, a subscore in each of these subfield areas is reported. Subject area subdivisions indicated by Arabic numerals may not contain equal numbers of questions.
• 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