Bio Technology is just what the name suggests. In this branch, there are two opposing sides, the aggressive side of Bio War and the path to improve the habitability of new planets.
Here, the player can try to develop better technologies to improve colonization of new planets by, for example, increasing the adaptiveness of one's citizens or the effectiveness of current terraforming procedures.
On the side of Bio War, the player can try to develop deadly plagues to wipe the enemy of the surface of a new planet, or even design a plague that converts the current population to the player side.
But be warned!
Bio War is a dangerous subject and occasional outbreaks can occur while developing the weapon.