Plagarised work

If you're directly quoting you should be using quotation marks.
What your lecturer was probably trying to convey is that the standard in your field would be to paraphrase the works and reference them accordingly rather than using a direct quote with quotation marks.
In any event you'll just have to wait and see what the outcome is.

Do you think that it may result in a reduction of marks?

I have no idea, it depends on how your coursework is assessed and also whether they flag it as plagiarism or not.

I’m just really worried about this. It’s my first essay and i’ve never referenced before

Hi i recently wrote an essay for my foundation year module. I used direct quotes from online sources and in text cited them. I didn’t however use quotation marks as my lecturer told me it wasn’t a common practice in biological science essay writing. I’m now worried that i’m going to be done for plagiarism because i didn’t use quotation marks and i didn’t change the wording of the direct quotes so i really don’t know what to do and im worried im going to get zero marks. My lecturer did tell the class that there has been some people who have plagiarised but i haven’t had a direct message from them so i assumed i was fine until today and im now stressing about it.