Plants reacting to light is called phototropism. As plants need light to survive, by growing towards the direction of the light they give themselves the best chance of gettingâ¦ the most light.   Plants can tell the direction of the light because their surface has chemicals that react to light.
By On 11/29/15 at 12:30 PM. Refugees undergo the strictest background checks of any group of people entering the U.S. While some lawmakers have criticized the process for not being strict enough, it can sometimes take longer than two years, and Syrians go through an additional screening. Above, 5-year-old Syrian refugee Leen works on her homework at her new home in Sacramento, California, on November 16.
Although refugees have been a constant and accepted part of human migration for centuries, the development of the nation-state and fixed borders in the 19th century caused countries to shun refugees and turn them into international pariahs.hen refugees flee from a less developed country to a developed country, the refugees can legally remain in the developed country until the situation in their home country has become stable and no longer threatening.