Which gas did volcanoes not produce in the precambrian era?
o
a. oxygen
o
b. sulfur
o
c. water vapor
o
d. carbon dioxde

Which best describes how the common cold spreads in the human body? a bacteria burst out of normal cells killing them b viruses replicate inside respiratory cells c bacteria inject dna into normal cells d viruses insert dna into bacteria

What percentage of light hits earth's surface directly?

Which of the following statements most accurately describes convergent evolution? the process in which two similar species evolve separately from each other and share similar characteristics the process in which a single species evolves into two or more new species the process in which two entirely different species evolve in response to each other the process in which two different species evolve separately from each other but still share similar characteristics