Define the following professions: paramedic, botanist, electrician, and pharmacist.

Here are the answers to the questions:

1. A person who helps sick people in emergencies is a paramedic.
2. A person who studies plants is a botanist.
3. A person who installs electrical wire is an electrician.
4. A person who sells drugs and medicines is a pharmacist.

Here are the completed sentences:

1. A person who helps sick people in emergencies is an $\boxed{\text{paramedic}}$.
2. A person who studies plants is a $\boxed{\text{botanist}}$.
3. A person who installs electrical wire is an $\boxed{\text{electrician}}$.
4. A person who sells drugs and medicines is a $\boxed{\text{pharmacist}}$.