You will need 4 years of college with a science major and usually a minor in science as well. You also need a good grade average (GPA) to apply to Med School and also do well on the MCATs (medical college aptitude tests). Medical college is 4 more years. This is basic. Then further training. 1-3 years as an intern/resident. Many programs for specialties require 1-6 more years.
Take an English class.. Medicine*
chemistry
Yes you need a degree http://www.wikihow.com/Become-a-Physician-Assistant
Maths is one of the subjects
There are quite a few subjects you need to become a well rounded lyricist. You would need music classes for example.
communication
mathematics
What subjects do i need to take to be a psychology and a book writer .
scientist
Anything that has to do with science.
You need A-C grades to become a teacher
If you're asking what subjects you need to take during your undergraduate years, the answer is the same you would need for medical school. You can find a medical school's pre-requisite courses on their website, but it usually includes a good deal of science courses such as biology, chemistry, physics, etc.
The subjects that you need for mechanics are English Science Maths and preferably Technology (you will need to get a grade C or above in all of these subjects to get the qualifications needed to become a machanic)