Nana's Angel Biscuits

1 cake or 1 pkg dry yeast (Rapid Rise)
4 T warm water (not too hot)
5 c all-purpose flour
1 t baking soda
3T sugar
2 t salt
1 c vegetable shortening
2 c buttermilk

Preheat oven to 425 degrees. Sift all dry ingredients (not yeast) into a large bowl. Cut in shortening with a pastry blender. Add buttermilk, then yeast dissolved in the warm water. Stir until thoroughly moistened; turn onto a lightly floured board and knead a minute or two. (No rising required.) Roll out to desired thickness and cut into rounds. Brush with melted butter and bake for 10-12 minutes or until lightly browned. Baked biscuits can be frozen.