According to the National Heart, Lung, and Blood Institute, adults need around seven to eight hours. For teenagers they recommend nine to ten, and at least ten for children.
Answer:
The total magnification of a cell is calculated by multiplying the magnification of the ocular lens (also known as eyepiece lens) and the objective lens.
A mutation is a change in trait. For example people who are lactose intolerant are normal, but people that can can drink milk without a problem have mutated. Hopefully this makes sense and helped.
Planet earth is the only known region of the universe to host life and so the basic criteria for life is based on observations made here. For an entity to be considered a living organism it must contain DNA or some other means of storing genetic information. The second criteria is that it must have some way of extracting nutrients from its surroundings. The organism must be able to respond to environmental stimulus and last but not least it must be able to reproduce.