- A plant stem is the vehicle for transporting water and food from roots to the rest of the plant
- If something is a vehicle for a process then that something performs that process
- Therefore, a plant stem transports water and food from the roots to the rest of the plant

- A plant stem transports water and food from the roots to the rest of the plant
- Transporting materials through a plant is a kind of function
- So, a function of a plant stem is to transport water and food from the roots to the rest of the plant

Hence, a function of a plant stem is to transport water and food from the roots to the rest of the plant
[Question]What is the main function of a plant stem?
[Context]- A plant stem is the vehicle for transporting water and food from roots to the rest of the plant 
- Transporting materials through a plant is a kind of function 
- If something is a vehicle for a process then that something performs that process