- Food contains nutrients for living things
- Nutrients are a source of energy for living things
- Therefore, food is a source of energy for living things

- Food is a source of energy for living things
- A living thing requires energy to grow and heal
- Hence, a living thing requires food to get energy to grow and heal

- A living thing requires food to get energy to grow and heal
- Living things eat their food source
- Hence, eating food is used to get energy by living things

So, eating food is used to get energy by living things
Q: Animals get energy for growth and repair from
Context:
- A living thing requires energy to grow and heal 
- Food contains nutrients for living things 
- Living things eat their food source 
- Nutrients are a source of energy for living things