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BIO123 Series

New Introductory Biology Courses and Labs for UC Davis

The College of Biological Sciences is revamping core biology at UC Davis to enhance STEM curricula. Replacing BIS 2A, 2B, and 2C, the BIO123 Series focuses on adaptation, heredity, ecology, evolution (BIO1); metabolism, DNA structure, and cell biology (BIO2); and challenges of multicellular life with evolved adaptations (BIO3). Optional labs BIO1L and BIO2L, now separate, emphasize inquiry-based approaches and multi-week projects for hands-on experience in biological techniques and hypothesis testing.

Evolution and Ecology

BIO1 Lecture and Discussion

BIO1L Lab

Molecules to Cells

BIO2 Lecture and Discussion

BIO2L Lab

Cells Through Organisms

BIO3 Lecture and Discussion

What's Changing

The BIO123 Series curriculum is designed to enhance student learning through an integrated and conceptual approach. The updated structure emphasizes hands-on experiences, problem-solving, and real-world applications, fostering deeper engagement with the life sciences. Some of the most notable changes include:

BIO123 Lectures

Sequencing of the courses will allow for improved student success as study skills and topics mastered in one course can be built on in subsequent courses. Topical themes can be connected and reinforced across the sequence, connecting to practical problems such as climate change, human health, and biodiversity conservation and ecosystem management.

BIO 1L and 2L 
  • Creation of a sequenced lab series that can be taken concurrently with BIO1 and BIO2 (2 additional units):
  • These courses have hands-on, hypothesis-driven, inquiry-based laboratory activities that meet 2.5 hours/week.
  • Their goal is to grow a student’s scientific mindset and build a more intuitive understanding of the molecular and biological world, and to enhance their ability to formulate and test hypotheses using current techniques in molecular and cellular biology, ecology, evolution and biodiversity.

Recommended Transition for Majors Requiring BIS2ABC

For majors that require a full year of introductory biology, or courses that require a full year of biology as a prerequisite, students should take BIO 1, 2, and 3. If laboratory experience is desired then requiring BIO 1L and BIO 2L is appropriate.

Replacing BIS2ABC Courses with BIO123 Courses and Labs

The introduction of the BIO123 Series will result in the eventual cancellation of courses in the BIS2 series. If you currently require BIS2A, B or C in your major's curriculum, or as a prerequisite for one of your courses, please use the collected BIS2ABC syllabi to familiarize yourself with their requirements. 

Currently, there are five scenarios where BIS2 courses represent instances where the change to the BIO123 Series will require substitutions to fulfill the prerequisite or major requirements:

  • If only BIS2A is required

  • If only BIS2A is required, we recommend the following replacements:

    Take BIO2 lecture (4 units). If lab component is desired, add BIO 2L. Note: BIO2 has prerequisites of BIO1 (4 units) and BIO1L (1 unit).

    Take BIS 010 – Everyday Biology (4 units).

  • If only BIS2B is required

  • If only BIS2B is required, we recommend the following replacements:

    Take BIO1 lecture (4 units). If lab component is desired, add BIO 1L.

  • If both BIS2A & BIS2B are required

  • If both BIS2A and BIS2B are required, we recommend the following replacements:

    Take BIO1 lecture (4 units) plus BIO1L lab (1 unit), and BIO2 lecture (4 units) plus BIO2L lab (1 unit).

    If lab component is not desired, take BIO1 lecture (4 units) plus BIO1L lab (1 unit), and BIO2 lecture (4 units).

  • If both BIS2B & BIS2C are required

  • If both BIS2B and BIS2C are required, we recommend the following replacements:

    To replace BIS 2B, Take BIO 1 (and 1L if lab desired). 

    To replace BIS 2C, take either BIS 70 or BIO 3 or other non-CBS courses to be listed here as they are identified. Note that if BIO 3 option is selected, BIO 2 will also be required since it is a prerequisite for BIO 3.

Syllabi of Potential Replacement Courses*

*This folder is populated with options within CBS, such as the new courses and labs in the BIO123 Series, as well as other CBS-administered courses, like BIS10 and BIS70. As various departments identify substitutions, we will update the pages above to include their recommendations. 

FAQs

  • Why are we making these changes now?
  • The new course series enhances small-group discussions, hands-on labs, and active learning to better prepare students for upper-division coursework. By focusing on core concepts and practical skills, the updated series allows for greater mastery and retention while maintaining a strong foundation in biological sciences.
  • How does the structure of the BIO123 series compare to that of the BIS2ABC series?
  • The new BIO123 series must be taken in sequence and separates labs and lectures into standalone courses (e.g., BIO1 and 1L). Lecture courses are now 4 units (3 units of lecture, 1 unit of discussion), while labs are optional 1-unit courses linked to the lecture. This structure increases small-group discussions and active learning while allowing flexibility for students and reducing the overall series by 1 unit.
  • How does the content of the BIO123 series compare to that of the BIS2ABC series?
  • Detailed learning goals for the BIO123 series are still being finalized by faculty committees. Summaries of BIS2ABC content are available HERE, and a proposed lecture schedule and course outline for BIO123 can be found HERE. BIO1’s extended description, including major topics and learning outcomes, is complete, with BIO2 and BIO3 in progress.
  • How is the material from the BIS2ABC series being reconfigured in the new BIO123 series?

  • BIO1 (Ecology and Evolution) retains BIS2B’s focus on natural selection, ecology, and population genetics but incorporates introductory phylogeny and diversification concepts from BIS2C. Some in-depth ecological and evolutionary content will now be covered in upper-division courses.

    BIO2 (Molecular and Cellular Biology) ensures a consistent, foundational understanding of cell structure, function, and metabolism. It introduces basic biological chemistry without requiring prior chemistry knowledge. Topics include metabolic processes (e.g., photosynthesis, glycolysis, fermentation) and key biomolecules (carbohydrates, lipids, proteins, and nucleotides).

    BIO3 (Integrated Organismal Biology) explores life’s diversity but focuses more on physiology, homeostasis, and organismal responses to the environment. Phylogeny is still included but with selective emphasis on evolutionary innovations.

  • What about BIS2C, Introduction to Biology: Biodiversity and the Tree of Life?
  • Key topics from BIS2C are distributed across the series. BIO1 covers the basics of phylogenies and major evolutionary innovations. BIO2 addresses the evolution of unicellular life and distinctions among bacteria, archaea, and eukarya. BIO3 highlights functional biology and adaptations in multicellular organisms (plants and animals) without systematically covering all organismal diversity. A broad survey of the diversity of life will still be available in the new BIS 070 course (Biodiversity and the Tree of Life).
  • How will these changes influence prerequisites for upper-division courses in BIS courses?

  • BIS101 currently requires BIS2A and BIS2B, which align with BIO1 and BIO2, and we anticipate no changes to these prerequisites.

    BIS102 and BIS105 currently require only BIS2A. Since BIO1 is a prerequisite for BIO2, this could introduce a “hidden prerequisite” for majors not already requiring BIO1.

    However, most majors that require BIS102 already include BIS2A and BIS2B, so this change will impact only a small number of students. Instructors can explore alternative pathways for students to prepare for these courses.

    BIS103 requires BIS102 and will see no additional changes.

    BIS104 requires BIS101, which already includes BIS2A and BIS2B (and hence BIO1 and BIO2).

  • How will these changes influence prerequisites for upper-division courses?
  • Departments will determine which of BIO1, BIO2, or BIO3 align with their course prerequisites. For courses that previously required BIS2ABC or a full-year biology introduction, the BIO123 series is recommended. Departments looking for broader coverage of organismal diversity across all life should consider requiring BIO70. A streamlined process for updating prerequisites will be shared when available.
  • How will the new series articulate with community college biology courses?
  • In the short term, articulation for the BIS2ABC and BIO123 series will both be acceptable. In the longer term, the BIO123 series is expected to articulate more easily with most community college courses than the current BIS2ABC series.