BIOLOGY

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.

To cover the broad field of the biological sciences, the subject matter on which the students are tested 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. However, 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

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 phemonena 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

This section deals with the 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