Determining sample dependence

#1
How do you determine if samples are independent?

I know that test scores of two separate groups of students are independent. Before-and-after measurements on the same group of students are dependent. But would test scores of biology and test scores of english for the same group of students be dependent of one another? (each student from the group has a biology and an english score, no before and after)

The students are the same between the two groups of scores so the scores are related to the student, but are they dependent from one another? Would a 2 sample t test be appropriate to test the two score sample means?
 

Dason

Ambassador to the humans
#2
Yes it would make sense to model those as dependent. At least if you can match the english and biology scores for each student.