Here are a few ways to use "biological" in a sentence:

* Scientific: "The study explored the biological mechanisms behind aging."

* Medical: "Doctors are investigating the biological causes of the patient's illness."

* Environmental: "The pesticide has a negative impact on the biological diversity of the ecosystem."

* Personal: "Our biological clocks are telling us it's time to sleep."

* Figurative: "He was a biological machine, working tirelessly to achieve his goals."

Let me know if you'd like to see more examples!