Tis is my bio discussion question... I have really no idea what to write on it...

Well, one place where you can talk about it is the gut where the process of peristalsis takes place. How does the pair of longitudinal and circular muscles work together?

OK... thx^^ other than that... what can I say... I need 2 more point...

There are the arteries too.

Now YOU think of the last one.

Google has some interesting links:
Muscular layer - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Muscular_layer)

Though the most common is within the gut. Maybe you can talk about the different parts of the gut: the oesophagus, the stomach, the small and large intestines, etc.