angle-up angle-right angle-down angle-left close user menu open menu closed search globe bars phone store

Biology Test


  • The test consists of approximately 188 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. In addition to the total score, a subscore in each of these subfield areas is reported.

Content Specifications

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


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

  1. 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 transmitter substances
      • Mechanisms of cell recognition, intercellular transport and communication
      • Cell wall and extracellular matrix
    5. Organelles: structure, function, synthesis, and targeting
      • Nucleus, mitochondria, and plastids
      • Endoplasmic reticulum and ribosomes
      • Golgi apparatus and secretory vesicles
      • Lysosomes, peroxisomes, and vacuoles
    6. Cytoskeleton: motility and shape
      • Actin-based systems
      • Microtubule-based systems
      • Intermediate filaments
      • Bacterial flagella and movement
    7. Cell cycle: growth, division, and regulation (including signal transduction)
    8. Methods
      • Microscopy (e.g., electron, light, fluorescence)
      • Separation (e.g., centrifugation, gel filtration, PAGE, fluorescence-activated cell sorting [FACS])
      • Immunological (e.g., Western Blotting, immunohistochemistry, immunofluorescence)
  2. 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
      • Whole genome expression (e.g., microarrays)
      • Regulation of gene expression by RNAi (e.g., siRNA)
      • Epigenetics
    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


The structure, physiology, behavior and development of organisms 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. Responses to environmental stimuli are examined as they pertain to organisms. Major distinguishing characteristics and phylogenetic relationships of organisms are also covered.

  1. Animal Structure, Function and Organization (10%)
    1. Exchange with environment
      • Nutrient, salt, and water exchange
      • Gas exchange
      • Energy
    2. Internal transport and exchange
      • Circulatory, respiratory, excretory, 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)
  2. Animal Reproduction and Development (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)
  3. Plant Structure, Function, and Organization, with Emphasis on Flowering Plants (7%)
    1. Organs, tissue systems, and tissues
    2. Water transport, including absorption and transpiration
    3. Phloem transport and storage
    4. Mineral nutrition
    5. Plant energetics (e.g., respiration and photosynthesis)
  4. Plant Reproduction, Growth, and Development, with Emphasis on Flowering Plants (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)
  5. Diversity of Life (6%)
    1. Archaea
      • Morphology, physiology, and identification
    2. Bacteria
      • 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


The interactions of organisms and their environment, emphasizing biological principles at levels above the individual are addressed. Ecological topics range from physiological adaptations to the functioning of ecosystems. Although principles are emphasized, some questions may consider applications to current environmental problems. Topics in evolution range from genetic foundations through evolutionary processes and to their consequences. Evolution is considered at the molecular, individual, population and higher levels. Some quantitative skills, including the interpretation of simple mathematical models, may be required.

  1. Ecology (16–17%)
    1. Environment/organism interaction
      • Biogeographic patterns
      • Physiological ecology
      • Temporal patterns (e.g., seasonal fluctuations)
    2. Behavioral ecology
      • Habitat selection
      • Mating systems
      • Social systems
      • Resource acquisition
    3. Population ecology
      • Population dynamics/regulation
      • Demography and life history strategies
    4. Community ecology
      • Direct and indirect interspecific interactions
      • Community structure and diversity
      • Change and succession
    5. Ecosystems
      • Productivity and energy flow
      • Chemical cycling
  2. 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. Macroevolutionary and microevolutionary processes
      • Gene flow and genetic drift
      • Natural selection and its dynamics
      • Levels of selection (e.g., individual and group)
      • Trade-offs and genetic correlations
      • Natural selection and genome evolution
      • Synonymous vs. nonsynonymous nucleotide ratios
    3. Evolutionary consequences
      • Fitness and adaptation
      • Speciation
      • Systematics and phylogeny
      • Convergence, divergence, and extinction
      • Coevolution
    4. History of life
      • Origin of life
      • Fossil record
      • Paleontology and paleoecology
      • Lateral transfer of genetic sequences

Download the Practice Book

< Back to: Test Content

Promotional Links

Ready to take a GRE® Subject Test?

Register Now

Send Only Your Best Scores

Approach test day with more confidence, knowing you can send the scores that show your personal best — only with the ScoreSelect® option.

Official Test Prep from ETS

Nobody knows our tests better than we do. We offer free practice tests and tips to help you prepare for your GRE Subject Test. Check them out today.