In a large bowl whisk together sugar and lemon zest. This step helps to bring out the lemon flavor. Add flour, poppy seeds (if using), baking powder, baking soda, and salt, and whisk until combined. Set aside. In a medium bowl, whisk together eggs, yogurt, melted butter, and lemon juice until combined and smooth. Pour the egg mixture into the flour mixture and stir with a wooden spoon or a rubber spatula just until combined. Fold in raspberries gently, being careful not to mash.