In order to create a text within a genre we need to know its common features. If you are asked to write a lab report, for example, you need to be able to analyse lab reports as a genre; this will help you notice and then replicate its organization and language in your own writing.
Depending on your academic background, you may have more or less experience with the type of text you are asked to produce. The more experience you have with a genre, the easier it will be for you to produce a similar text.
For example, if you are studying in a field in the arts and humanities, or the social sciences, you might be very familiar with essays. The moment you read the word essay, your mind probably went directly to a particular type of text. But do you know how to create a conservation plan? If you do not study archaeology or in another field that uses them, chances are you don’t know what a conservation plan looks like.