Failure would ruin your life

It does, of course, cause difficulties if you fail an exam, but do get things into perspective.

Unless you have understood everything on the course, it isn’t worth taking the exam

There are usually choices to be made in the material you present in an exam answer.  No exam ever asks you to “write everything you know about ...”

Examiners are out to ‘trick’ you

They really aren’t!  We just want you to be able to show what you’ve learned.

Exams suit people who have a good memory

That may be true in some subjects, but there is a lot of English work which really can’t be done by memory alone.  Often it is skills (eg of analysis or argument) which are being tested primarily.  You will need some facts/names or quotes to hand, but memory really sisn’t the main thing for English exams.

There are marks available for specific points made

That’s not how it works.  The examiners are looking for evidence of the assessment objectives, not checking against a list of things to be mentioned/discussed.