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The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere

Why are current extinctions of concern to enviromentalists?

During dna replication,each strand of dna is used as a template to produce a complementary strand of dna. this process is shown below. which base will attach to location