Metallic elements with high atomic weights; (e.g. mercury, chromium, cadmium, arsenic, and lead); can damage living things at low concentrations and tend to accumulate in the food chain.
A process of inserting new genetic information into existing cells in order to modify a specific organism for the purpose of changing one of its characteristics.
The warming of the Earth's atmosphere attributed to a buildup of carbon dioxide or other gases; some scientists think that this build-up allows the sun's rays to heat the Earth, ...
The world's most popular fruit. The most common U.S. variety is the yellow Cavendish. They are picked green and develop better flavor when ripened off ...
5 词条
