I hope all is well.
General knowledge can be important in certain exams, especially the written portion just to illustrate your knowledge and understanding of current events or even when illustrating your understanding on certain issues. The more students read newspapers, legal or medical articles, and watch the news, the more general knowledge they will acquire.
If you are planning on taking an entrance exam, such as the GRE (masters programs and physical therapy schools), MCAT (medical schools), PCAT (pharmacy schools), or LSAT (law schools), it might be best to invest in a preparation book you can find online through Amazon, eBay or visit your local Barnes and Nobles to better prepare. They have multiple choice questions as well as some essay preparation, which can help with testing and practice your general knowledge in terms of essay writing.
Hope this helps!