Preheat oven to 350 degrees. In a bowl mix together the flour, baking powder, baking soda and salt. Set aside. Mix the 1/4 cup lemon zest with the 1 3/4 cup sugar. Mix and muddle the zest into sugar a bit with the back of a wooden spoon. Cream butter and sugar/zest together in the bowl of an electric mixer and mix for 3-5 minutes until light and fluffy. Addeggs one at a time and vanilla - mix well. Scrape down sides of bowl.
In a separate bowl, add 3/4 cup lemon juice to the sour cream or buttermilk and mix together. On low speed, gradually add the flour mixture and sour cream to the butter mixture, alternating mixtures. Scrape down sides if needed. Stir in the poppy seeds. Pour mixture into a buttered and lightly floured bundt pan that has been tapped out.
Bake cake for 20 minutes then rotate and continue for another 15-25 minutes or until a wooden skewer inserted in to the cake comes out clean. The cake will begin to pull away from the sides and middle tube. Let the cake cool on a rack for 15 minutes. Invert the cake onto a cake plate then brush immediately with the lemon syrup. Then allow to cool completely before glazing it.
While the cake is baking, prepare the Lemon Syrup and Lemon Glaze. For the lemon syrup, heat the sugar and lemon juice over low heat until sugar dissolves.
To prepare the lemon glaze, in a small glass bowl combine the sugar, lemon zest, lemon juice and mix well with a wire whisk. Add more lemon juice until desired consistency. Drizzle over cooled cake and sprinkle with poppy seeds.