| Questions | 5 |
| Topics | Carbon Cycle, Circulation, Core, Prefixes, Vitamins |
The carbon cycle represents the ciruit of carbon through Earth's ecosystem. Carbon dioxide (CO2) in the atmosphere is absorbed by plants through photosynthesis. Plants then die and release carbon back into the atmosphere during decomposition or are eaten by animals who breathe (respiration) the carbon into the atmosphere they exhale and produce waste which also releases carbon as it decays.
Like the respiratory system, the circulatory system serves to transport oxygen throughout the body while removing carbon dioxide. In addition, the circulatory system transports nutrients from the digestive system.
The Earth's core is divided into the liquid outer core (1,430 miles or 2,300 km radius) and the solid inner core (745 miles or 1,200 km radius).
A prefix is added to the base units of the metric system to indicate variations in size. Each prefix specifies a value relative to the base unit in a multiple of 10. Common prefixes are:
| Prefix | Symbol | Relative Value | Example |
|---|---|---|---|
| mega | M | 106 (1,000,000) | Mm |
| kilo | k | 103 (1,000) | km |
| base unit | N/A | 1 | m |
| centi | c | 10-2 (1/100) | cm |
| milli | m | 10-3 (1/1,000) | mm |
Vitamins are necessary for a wide variety of bodily processes. Some vitamins like Vitamins A and C come from diet but others, like Vitamin D, are generated in response to sunlight.