Answer:
Here is some background information...
Explanation:
Leeuwenhoek (1633-1723) used melted glass balls to form lenses for apparently crude simple microscopes that nevertheless magnified up to 275 times! Modern tests have concluded that he could have achieved a resolution of two micrometres.
Nervous System
Skeletal System
Muscular System.
The Nervous System fires electrical signals to your muscles, galvanizing them into action and making them move. The Skeletal System helps to support the Muscular System and move blood throughout your body so your body can receive oxygen. Your Muscular System in turn keeps your heart beating and helps you with locomotion.
They increase in number and they are more specialized