MAJOR: The major consists of nine Biology courses (36 units) plus Senior Comprehensive Seminar (Biology 490, 4 units), and five supporting courses (20 units). Required Biology classes are Bio 105, 106, 110 or Bio 115, Bio 130, Bio 490, and seven additional 200- and 300- level Biology classes that satisfy the breadth and depth requirements defined below.

Two semesters of introductory biology are required. In these courses, students are exposed to basic biological principles and the diversity of life.

The introductory courses may be taken in any order, but at least one should be taken during the first year. One course must be in organismal biology, stressing diversity and the relationship between structure and function (Bio 105, 106, 110 or 115). The second course must be in cellular and molecular biology (Bio 130) and provide a broad introduction to the biochemistry, physiology, and molecular biology of prokaryotic and eukaryotic cells. 100-level Biology courses are not open to senior Biology majors.

To meet the requirement for breadth within Biology, majors will take four classes, one from each of four biology subject areas: Cellular and Molecular Biology (Bio 221, 222, 224 or 226), Environmental Biology (Bio 106, 260, 270 or 275), Evolutionary Biology (280), and Organismal Biology (Bio 240, 250 or 275) 200 level requirements. In 300-level courses, students engage deeply with a particular specialized subject. Three 300-level courses (at least two of which must be Biology laboratory courses) are required.

One seminar course (Biology 490) is required to fulfill senior comprehensive requirements.

Five supporting classes are required for the major: Two semesters of chemistry (Chemistry 120 or 130, and 220); three quantitative courses, including:

1) a calculus course:

  • Calc I
  • Students who pass out of Calc I instead take an additional quantitative course from those listed below

2) one data analysis course from the following list:

  • Bio 260
  • Bio 268 or Math 150 or Psych 201
  • Geo 150 or 255
  • Cog Sci 255

3) one additional quantitative course either from the list above or from the following list:

  • Calc II
  • Math 210, 212, 214, 310, 312, 320, 322, 330, 332, 340, 342, 350, 352, 354, 360, 362, 370, 380, 382, 392, 396
  • Comp Sci 210, 211, 311, 353
  • Comp Sci 151, 157, 161, 165, 167 (2-unit courses*)
  • Chem 221 (OChem II), Chem 300 (PChem), Chem 301 (BPChem)
  • Physics 110, 115, 120, 125
  • Cog Sci 242
  • Bio 270, 326, 340, 369, 370

*For 2-unit courses, students must complete two, 2-unit courses to fulfill one quantitative requirement

Biology majors must complete these courses within the Biology Department at Occidental:  at least two of the four 200-level courses and at least two 300-level electives. A course used to fulfill one requirement cannot fulfill another major requirement. 2 unit and AP courses, AP exams or placement exams do not meet requirements for the major.

Students intending to apply to health professional programs or graduate programs in Biology should include four semesters of Chemistry, two semesters of Physics, and two semesters of Calculus in their course plan. Pre-professional students are strongly encouraged to consult with the Health Professions Office early in their career. Students planning to apply to graduate programs in Biology are also advised to include research (Biology 395) in their program of study, and may wish to select an emphasis (see below).

Students intending to obtain a teaching certification in biology should contact the Education Department as early as possible for advice on course selection. Additional advice concerning courses and career planning may be obtained from the major advisor.

The Biology Department encourages international study for Biology majors. Among the semester options available are programs in Tropical Biology in Costa Rica, Global Medicine and Public Health in Costa Rica, and direct enrollment at James Cook University in Australia (with strengths in Marine Biology and Tropical Biology.) Students may receive credit towards the Biology major and to meet Core distribution requirements. See the International Programs Office and Professor Braker for more information.

EMPHASIS WITHIN THE MAJOR: Students may construct an individual program to meet the Biology major requirements, or they may choose an emphasis in Cell and Molecular Biology or Marine Biology, or the Environmental Science Concentration in Biology.

Cell and Molecular Biology Emphasis: This emphasis is designed for students who are interested in pursuing a career in the health professions or graduate school in cellular or molecular biosciences. Cell and Molecular Biology encompasses a wide range of studies, including: gene expression and regulation, transmission of genes between generations, cell-to-cell communication, cell physiology, the biochemistry of DNA and RNA, the development of a fertilized egg into a multi-cellular organism, the biology of microbes, the cellular and molecular mechanisms that drive the specialized functions of the immune system, the nervous system and other organs and tissues. All requirements for the Biology major apply, with the addition that students must take two of the three courses at the 200 level as part of their program of study: Bio 221, 224, and 226 as part of their program of study. At least two of the required three courses at the 300 level must be chosen from the following list: Bio 320, 322, 323, 325, 326, 330, 333, 340, 349 and 350. Students are strongly encouraged to participate in research with faculty (Biology 395). Courses in organic chemistry and physics are strongly recommended for students planning to attend graduate and professional schools.

Marine Biology Emphasis: The marine emphasis is designed for biology majors who are interested in pursuing careers or graduate school in the marine sciences. Marine science is one of the most integrative fields in biology with research topics ranging from molecular methods for the classification of marine bacteria to the effects of global warming on fisheries. Students are required to satisfy all the requirements for the biology major and must take four of the following upper-division courses: Biology 260, 268, 344, 356, 368, 369, or Geology 245. These courses may also satisfy biology major requirements. In addition to the coursework, students are encouraged to participate in as many of the following activities as their schedules allow: 1) independent or collaborative research with faculty (Bio 395), 2) scuba diving as part of a club or research team, 3) participation in programs (academic year and/or summer) at marine science institutions, 4) participation in faculty led field trips, and/or 5) attendance at seminars on marine topics at Oxy and other nearby campuses. Students graduating with a marine emphasis will have strong lab/field research experience, know the common local marine organisms (plankton to mammals), and be able to discuss the pertinent physical and biological processes affecting the southern California marine area. Students interested in joining this emphasis should monitor our web site at and contact one of the marine faculty to discuss their course of study.

Environmental Science Concentration in Biology: Environmental Science is a Concentration that explores earth processes and ecosystems and develops skills that students need for environmental analysis and problem-solving. The Environmental Science Concentration is designed for students who want to more fully understand the biological and geologic foundation of Environmental Science and provides them with a shared academic experience and expertise within a specific scientific field. Participation in a core of introductory courses establishes the interdisciplinary breadth necessary for understanding complex environmental problems. Further specialization gives students a strong background in Biology or Geology, preparing them to become involved in research projects, fieldwork, internships, and environmental studies. Students will receive their Bachelor of Arts in Biology or Geology with an Environmental Science Concentration, enabling them to pursue graduate work in Biology, Geology or Environmental Science, and professional careers in these and related fields.

Students complete the Environmental Science Introductory Core and additional courses to complete a major in Biology or Geology.

Environmental Science Introductory Core: (7 courses)
First level courses:

Earth: Our Environment (Geology 105)
Introductory Biology (105, 106, 110, or 115)
Introductory Economics (101)
Second level courses:
Spatial Analysis with GIS (Geo 255)
Earth's Climate: Past and Future (Geo 245)
Biodiversity and Organization of Marine and Terrestrial Ecosystems (Bio 260)
or Ecology (Bio 270)
Environmental Economics (Econ 301) or another 300-level course dealing with environmental
policy, chosen in consultation with Academic Advisor.

Environmental Science Concentration in Biology
Environmental Science Core (above) plus:

Introduction to Cellular And Molecular Biology (Bio 130)
Vertebrate Physiology (Bio 240), Plant Form And Function (Bio 250), or Flora Of Southern California (Bio 275)
Evolutionary Biology (Bio 280)
Three 300-level courses (e.g., Bio 350, 360, 369, 377, 380)
Chemistry 120 and one other chemistry course with lab
Mathematics through Math 120 (or equivalent)
or Math 110 and a Department-approved statistics course.

MINOR: Five courses (20 units) are required for the minor. These include any two of our introductory courses (Biology 105, 106, 110, 115 and 130) and any three additional courses at the 200 or 300 levels, two of which must be taken in the Biology Department. Independent Studies and Advanced Placement credit may not count toward the minor.

WRITING REQUIREMENT: Students majoring in Biology will satisfy the final component of Occidental College's campus-wide writing requirement by successfully completing two courses at the 300-level (or appropriate course work). Students should familiarize themselves with the departmental requirement at the time of declaring the major. See the Writing Program and consult the department chair for additional information.

HONORS: The Honors Program at Occidental College is designed to allow the superior student’s attention to be focused on a directed investigation for a sustained period of time. It is expected that students admitted to the College Honors Program will have established themselves as outstanding prospects for individualized work in the department of their major and will also have established themselves as doing work of very high quality in all that they have undertaken at Occidental. Student admission to the College Honors Program will be by formal action of the faculty in the student’s major department (taken from the College Catalogue statement on Honors).


  • Student typically will have worked on a research project for 2 semesters (or 1 semester + summer session) minimum, before applying for honors
  • Student must have an average GPA of 3.25 (college policy)

Application Process

  • Student should discuss with their research mentor and submit an official Letter of Intent to the Biology Chairperson by the beginning of their senior year, or sooner. 
  • The letter of intent should include a summary of research results (realized and projected), as well as significance of the research and any projects in progress at the time of submission.
  • Applications will be evaluated by the Biology faculty.
  • Students nominated for honors will be notified by the Biology Chairperson.

Completion Process

  • At the time of nomination, each candidate will be assigned an honors thesis committee of two Biology faculty members, in addition to their faculty mentor. This committee will be available for guidance and to help ensure that milestones are met in a timely manner.
  • Milestones will include a thorough literature review, written drafts of the introduction, methods, and results sections, including draft figures, and a final discussion section, as well as preparation of a public seminar.
  • The candidate must complete a written thesis of their work. It is expected that the student will spend part of their final semester or directed research writing the thesis.
  • The written thesis will be due to the mentor by Monday in the 4th week of February.
  • The revised honors thesis will be due to the committee by Monday in the 3rd week of February.
  • The thesis will be reviewed by committee, and final revisions must be submitted by the last day of March.
  • Honors candidates will also give a presentation on their research during the week of April 15. These presentations will last approximately 15 minutes, with 5 min for questions. 
  • Honors grades are Pass/Fail and reported to the registrar by the Chair.  The chair will inform the students of their grade when it is decided upon by the committee.

GRADUATE STUDY: Graduate study toward the degree of Master of Arts under the thesis plan may be undertaken in Biology by properly qualified students. Thesis projects may be elected in any of the following fields: cellular biology, developmental biology, immunology, microbiology, molecular biology, neurobiology, biochemistry, comparative physiology, animal behavior, environmental biology, ecology, systematics and evolutionary biology, and marine biology. Graduate courses, numbered 500 and above, are valued at five units unless otherwise noted. Consult the department chair for further information on graduate studies.

  • Phone:
    (323) 259-2697
  • Fax:
    (323) 341-4974
  • Email:
  • Location:
    Bioscience Building
    1600 Campus Road
    Los Angeles, CA 90041
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