A1) Students who exhibit more undesirable academic behaviors feel more strongly that work contributes to less time and energy for studying.
A2) The class is believed to assess subjective feelings of increased knowledge and awareness of the need for a coherent system for studying in response to taking the course.
B1) Fifteen weeks later, the mice were sacrificed and the tissues removed for study.
B2) It's not just a quiet place. I want to have a quiet place for study, but I want to have a social room - a noisy place where you can meet other people.
In A1), A2) studying is used while in B1), B2) study is.
What's the difference between two uses of studying and study. Are they interchangeable?