I'm building a site with many dynamically created URLs. Basically I have categories and subcategories and I format my link "category/subcategory", however only index.php is being used and content is generated according to the selected categories. There are no direct links to each and every category/subcategory (the generated URL is SEO friendly, no GET parameters whatsoever), I'm trying to achieve a minimalistic design so adding links in bulk is not really an option. Will Google and other search engines be able to index my dynamic pages? The pages are reachable through a select tool where the user can select and/or search for the required categories. I hope i managed to explain my problem properly if not I will try to add some pictures. 

Thanks for the responses!