Presenting evidence - quiz feedback...
Not referencing the author of the original idea, intentionally or not, leaves you open to accusations of plagiarism.
Again, as above, there is the danger that you could be seen to pass this off as your own work and leaves you open to accusations of plagiarism.
We would regard this an incomplete or sloppy referencing when using Harvard. However, some referencing conventions don't cite the date in the main body of the text, so it depends which method you are using.
As with No. 1 above, the reader will assume that you have compiled and completed this research unless you cite where you found it. If it is isn't your work, this leaves you open to the accusation of plagiarism (and in this case, will be quite easy for the reader to spot!)
You need to attribute the author to the idea - referencing in the reference list or bibliography is not enough. So, here again you may be open to the accusation of plagiarism.
Rewrite what you read in your own words, this way you will avoid plagiarising someone else's work. Remember to cite where the original ideas came from too.
This is plagiarism, quite simply. Adding some of you own ideas does not remove the fact that you have used someone else's work.
This is also plagiarism. It is possible that you may have good, peer discussion with others about your assessments, however, when it comes to writing it up, it has to be your work alone.
Very simply, the image was not your work, so you have to acknowledge it. (Unless you find a source online that gives you permission to use their work or is copyright free.)
Once again, this needs to be referenced - whether orally or on a slide etc. Otherwise, this could be seen as plagiarism.
This is known as 'self plagiarism' and is still considered plagiarism by many even if it is your own words. Plagiarism detection technology tools, such as Turnitin, which many universities use to check for plagiarism can pick this up, so it is better to reword work you have written before.
It is good practice to get someone to proof-read your work, and you don't always have to pay someone to do it! Most universities will have services that can help you, sometimes run by their student services or unions, particularly if you have a disability. Or you can ask a friend. However, if you then pay someone to edit your work, you are changing your work, and it is no longer just yours. You can have suggestions, but you have to do the edits yourself, otherwise...