Answer:
Trees have to adapt to their environments in order to survive them, from the shape of their leaves to the size of their branches. They also have had to adapt the shape of their crowns to the kind of climate they live in so that they may have better chances at survival.
In warm areas with lots of sunlight for instance, you will see broad cones as the tree takes advantage to get as much sunlight as it can. In colder areas where snow is abundant, trees will be conical in shape so as not to gather too much snow when it falls.
Fuel is use to produce a force to accelerate in a new direction.In the void of space the object will continue its velocity until somthing acts upon it.(newtons first law of motion)
It could be dinosaurs, or a specific species... could you be more specific with what it's related to?
D-walls and doors would represent the cell membrane