Final answer:
Tim's routine of smoking marijuana daily to help him concentrate at school is an example of substance abuse, which could lead to drug addiction. This is distinct from tolerance and withdrawal, which are consequences of prolonged drug abuse and dependence.
Step-by-step explanation:
Tim, a high school junior, has been smoking marijuana daily before he comes to school and has claimed it helps him focus on his assignments for the day. Tim's actions are an example of substance abuse, which is defined as the use of a drug without the advice of a medical professional and for reasons not originally intended. If Tim continues to use marijuana in this way, it may lead to drug addiction, a compulsive use of a substance such as a psychoactive drug despite negative consequences that such use may entail. It is important to differentiate this from tolerance, which involves needing more of the drug to achieve the same effect, and withdrawal, which includes negative symptoms experienced when drug use is discontinued. Both physical and psychological dependence can develop as a result of drug abuse and addiction.