Biology 1222 or 1223;
Chemistry 1050 or the former Chemistry 1020 or 023;

plus 1.0 additional course, with no mark in these principal courses below 60%.

Additional requirements (which may be counted towards the 3.0 principal courses):
1.0 course from: Calculus 1000A/B or 1100A/B and one of Calculus 1201A/B, 1301A/B, 1501A/B, Linear Algebra 1600A/B, Statistical Sciences 1024A/B, or Mathematics 1225A/B and 1229A/B or the former Mathematics 030. This requirement must be completed by the end of second year.

3.5 courses: Earth Sciences 2200A/B, 2206A/B, 2250Y, 2260A/B, 2261A/B, 2265A/B, 3314A/B.
1.0 course from: Earth Sciences 2240F/G or 2241A/B, 2266F/G, 3340A/B, 3369A/B, 4400A/B, 4460A/B, 4461A/B, 4462A/B.
0.5 course: Biochemistry 2280A.
2.5 courses: Biology 2290F/G, 2382B, 2483A, 2486A, 2581B.
0.5 course from: Chemistry 2213A/B or Earth Sciences 2230A/B.
1.0 courses from: Biology 2240F/G, 2244A/B, 2471A/B, 2484A, 2660A/B, 3404F/G, 3651A/B, the former 216b or 328a,  Microbiology and Immunology 2100A, the former 450b. Note: Biology 2244A/B is recommended.
1.0 or 1.5 courses from: Earth Sciences 4490E or Biology 4999E (1.5 courses), with a mark of at least 70%.

Note: If Biology 4999E is chosen the module will consist of 10.5 courses.