Various combinations for B.Sc are,

Applied Mathematics:Pure Mathematics and/or Physics.

Biochemistry: Chemistry, Microbiology, Botany, Computer Science or Zoology.

Botany: Chemistry, Microbiology or Zoology.

Chemistry: Biochemistry, Geology, Mathematics, Microbiology, Physics, Zoology.

Computer Science: many other sciences, but especially GIS.

Geology: Chemistry, Physics, GIS, Computer Science, Soil Science, Geography.

Geographic Information Systems (GIS): Botany, Computer Science, Geography,Geology, Physics, Statistics, Zoology.

Geography: Botany, GIS, Geology, Computer Science, Zoology, Chemistry.

Pure Mathematics:Applied Mathematics, Chemistry, Computer Science,  Mathematical Statistics, Physics.

Mathematical Statistics:Computer Science, GIS, Mathematics.

Microbiology:Biochemistry, Botany, Chemistry.

Physics: Applied Mathematics, Chemistry, (Pure) Mathematics.

Zoology: Biochemistry, Botany, Geography, Geology, GIS, Microbiology