golden retriever heat?

Question
I have a 12 month old female golden retriever that I have never noticed being in heat.  We recently got a 6 month old male G.R. who is very interested in the female, but she bites and growls at him when he comes near.  Is it normal that she has not had her cycle yet and shouldn't she at least play with the male instead of biting at him?

Answer
Most females have their first heat cycle sometime the second half of their first year.  It isn't that uncommon for it to come after the first year.  I am surprised she isn't more welcoming of him unless he is being quite obnoxious.  

Might I ask why you don't go ahead and spay and neuter them?  If you are asking such basic questions I doubt if you have done the serious research it would take to select dogs that might be worth breeding.  To understand what I am talking about, read some of the material starting at http://www.woodhavenlabs.com/articles.html#breeding