Cast fossils form when a mold is filled in. Once a hollow mold is present, they are filled in with minerals that form a solid.
Mold fossils:
Mold fossils are an imprint mark made in a rock or sediment. They are hollow, and are often leaves, teeth, claws, and more.
True Form fossils:
True Form fossils are big parts of an organism went through a process called petrification, in which their body part was replaced by minerals which hardened to become rock.
Animals have a mitochondria, a nucleus, and a cell membrane, bu they do not have chloroplasts. You can only find chloroplasts in human and plant cells, not a animal's cell. Hope it helps!
The independent variable is that in which the result is dependent on. For experiments, this is usually the item being varied. For this case, what is being varied is that one group is given caffeine while the other is not. That makes the amount of caffeine given to be our independent variable.
