Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch Bundt pan.
In a large bowl, stir together cake mix and poppy seeds. Make a well in the center and pour in yogurt, water, oil, sugar, eggs and lemon juice. Beat on low speed until blended. Scrape bowl, and beat 4 minutes on medium speed. Pour batter into prepared pan.
Bake in the preheated oven for 45 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool.