In psychopathology, the biological perspective is the perspective that postulates that mental disorders have a biological root (usually in the brain, genetics or nervous system). Therefore, this approach studies psychological issues based on the physical basis and explanations for them.
In this example Linda goes to a psychiatrist and he believes that the main cause of her depression stems from a disruption in her levels of serotonin. We can see that <u>he's explaining the psychological issue (depression) based on the physical basis to it (levels of serotonin in the brain). </u>Therefore, he is using the biological perspective to diagnose her problem.