With repeated use of drugs,the tolerance level of the receptors present in our body ......

Which of the following chemicals is present in tobacco?

Given below are two statements with respect to the neurotransmitter,$Dopamine$.
Statement-$I$: Degeneration of $Dopamine$-producing neurons causes $Parkinson's$ disease.
Statement-$II$: $Dopamine$ level increases due to cocaine.
Choose the most appropriate answer from the options given below.

From which plant is the drug marijuana obtained?

Tunnel vision is caused by

Select the correct statement from the ones given below.