Nerves are cells that can detect any type of pressure, movement, or anything of that nature. If we didn't have nerves, we couldn't feel pain. If the nerves in a foot are damaged, you wouldn't feel the pain of it being burned.
Fluid, rolling, air resistance, and not sure about the last one.
It will be half
A normal cell contains 46 chromosomes.
Gametes only contain 23 because they will be paired with an opposite gamete cell upon fertilisation
- Egg contains 23
- Sperm contains 23
Together they make the normal amount of 46
The system of classification relates to the diversity of species because the system of classification is how we organize the diversity of species. With out it we would have a hard time trying to determine which animals belong with which group. There would be no order, just chaos of trying to determine animal likeness of one another.
To cut this answer short, it helps them organize organisms.