You can make the most of your snow days by using them for revision. Spend an hour each day to replace your Biology lesson using these resources.
Make sure that you are familiar with the updated learning outcomes by visiting the SQA page
http://www.sqa.org.uk/files_ccc/CfE_CourseAssessSpec_N5_Sciences_BiologyCD.pdf Look at pages 8 to 14.
http://www.bbc.co.uk/education/subjects/zync87h (Try the on line tests.)