<span>Russell's case (two illnesses: bipolar disorder and substance use disorder) illustrates </span>comorbidity. The term comorbity is used in medicine to denote a presence of two diseases or disorders, one primary and one additional, both occurring at the same person.
The answer to the question above is a cell.
These are known as Hormones. Hormones are chemical messengers that are released in one tissue normally endocrine glands for example, adrenal glands, pituitary glands, and transported in the blood stream to alter the activities of specific cells in other tissues. Hormones serves as messengers, controlling and coordinating activities or processes such as growth, metabolism and fertility in the body.
they combine the DNA of two different organims.
Explanation:
they join together genetic material especially the DNA from different biological species
It is definitely not a primary source: this would be a book itself.
Now, is it a tertiary source? I don't think so: the author of the review should have read the book and should only be referring to this book in the review.
I think it's a secondary source.