Which correctly describes crossing over?

Approximately what portion of the foods that we eat have been genetically modified in some way? a.fewer than 10% b.about 50% c.nearly 100%

Natural resources are any materials that humans obtain from the earth to meet our wants and needs.

Which of the following happened during the precambrian era? the first prokaryotic cells the first eukaryotic cells development of photosynthesis all of the above