The primary function of the carbon cycle is to recycle the supply of carbon on Earth.
For mutations to affect an organism's descendants, they must: 1) occur in cells that produce the next generation, and 2) affect the hereditary material. Ultimately, the interplay between inherited mutations and environmental pressures generates diversity among species.
You can do golden rice. It was genetically modified to produce beta carotene, which rice does not usually have. When metabolized by the body beta carotene is turned to vitamin A which is essential to human vision, immune systems, and healthier skin
The fish that were following the other fish around.