An example where space would be a limiting factor would be this: Wolves live in a very good habitat for them - there are plenty of animals to be found and eaten. However, because their current habitat is rather limited, they cannot expand beyond a certain size because otherwise they would interfere with the habitat of each other and also reduce the amount of necessary food in the environment.
it is the force with which a body is attracted toward Earth or another celestial body. This means that when you are in space, away from Earth, objects do not weight anything since they do not feel gravitational attraction to the Earth. Objects can have a large mass, but weigh nothing.
A microscope is an instrument which makes an object appear bigger than it is. It took the invention of this relatively simple tool to lead to the discovery of cells<span>. In the 1660s, Robert Hooke began using microscopes to look at all sorts of materials. Anton van Leeuwenhoek took up similar work in the 1670s.</span>