The homology of animals is based on scientists current understanding on the evolutionary history of living species.
There were two approaches for the planetary paths. The idea about the planets revolving around the Earth, the planetary paths were plotted and were erratic. It was not relevant to the laws of motion and gravity. That fact was neglected by the believers in an Earth-centered Solar System.
Sun-centered Solar System was theorized by Copernicus. The paths assumed to be relatively circular (or elliptical).
Manipulated Variable:The speed working on maths problems
Responding Variable: The group that use¬ using a calculator
Controlled Variable:The same maths quetions
<span>Sclerenchyma cells are the strongest. They have a second cell wallwhich is hardened by lignin, making them very tough and durable.</span>
