The cell membrane is the structure across which substances must pass if they are to enter or leave a cell.
They do this by a process called diffusion.
Substances such as glucose and oxygen diffuse into a cell.
While carbon-dioxide and water diffuses out of a cell.
National 5 & GCSE Biology RevisionNon-Fiction
National 5 ( and GCSE ) revision book to help you revise for your exams. This is only the work of the account and is not SQA or other qualification authority endorsed, you have to rely on other revision materials aswell as this book