How to create a dynamic drop down list from multiple values?

I have some data in a tabular format in one sheet (Sheet1) with some table heads. In the Sheet2 in cell A2 I've created a drop down list.
What I want to do is when I select an item from that drop down list then in cell B2 of Sheet2 there will be a dynamic drop down list of all the matches (doing lookup or something in Sheet1's data).

Desired result in Sheet2 should look like below :

sample1.jpg

Please help..