Many workbooks have the answers in the back of the book or on the publisher's website. At the collegiate level, some biology departments provide opportunities for students to get help from graduate student instructors or their peers.
Many textbooks have an optional accompanying workbook that students can use to give them more practice on specific subjects. Textbooks often have their own set of questions at the end of each chapter as well. The answers to textbook questions are often found in the back of the textbook, but sometimes textbooks only include answers for odd- or even-numbered questions. Workbook answers are often found online on the publisher's website.
The main difference between textbooks and workbooks is that workbooks are meant to be written in, leaving room on each page for the student to work on a problem and write his answer. These books often cost far less than textbooks and are not always a course requirement.
Recent studies have shown that factors involved with studying may affect how well a student does on an exam. Distributing practice throughout the semester, as is often done when using a workbook, instead of cramming is one of the most effective ways to prepare for an exam. Reading study material out loud is also effective.