| Questions | 5 |
| Topics | Atomic Number, Cell Division, Periods, Spinal Cord, Terrestrial Planets |
The Periodic Table of the Elements categorizes elements primarily by the number of protons in their nucleus (atomic number) and secondarily by the characteristics they exhibit.
Cell division is the process by which cells replicate genetic material in the nucleus. Cell division consists of several phases:
| Phase | Major Process |
|---|---|
| interphase | chromosomes replicate into chromatids and the cell grows |
| prophase | chromatids pair up |
| metaphase | paired chromatids move to opposite sides of the cell |
| anaphase | cell elongates and nucleus begins to separate |
| telophase | separation of nucleus is complete resulting in two new nuclei |
| cytokinesis | cytoplasm and cell membranes complete their separation resulting in two separate cells |
The rows of the Periodic Table are called periods and contain elements that have the same number of electron shells ordered from lower to higher atomic number.
The spinal cord connects the brain to the body's network of nerves. It carries impulses between all organs and the brain and controls simple reflexes.
The four planets closest to the Sun (Mercury, Venus, Earth, and Mars) are called terrestrial (Earth-like) planets because, like the Earth, they're solid with inner metal cores covered by rocky surfaces.