Preheat oven to 400 degrees F. Dissolve yeast in water, set aside. Mix dry ingredients. Cut in shortenlng with pastry blender. Slowly add yeasted water. Turn dough out on floured pastry board and knead lightly as for regular biscuits. Roil and cut with biscuit cutter. Place rounds in a greased pan. Let the biscuits rise slightly before baking for 12 - 15 minutes or until browned and done.