I think QA responsibilities varies from place to place. In some places, it might be as easy as coming up with scenarios, going through the website, making sure the new features pass the said scenarios etc...whereas in other places where they have automated testing, you might have to know automated testing tools such as Selenium and maybe some HTML, javascript and various web protocols and also maybe some build scripts and tools such as Gradle, Hudson etc...so you can automate testing from scratch by manipulating the database and use customized data...in some places where they use TDD you might even have to write unit tests in which case, you'd also have to know .NET, Java or other backend languages/frameworks, OOP, Dependency Injection etc...so, it all depends. Best of luck.