Which of the following Eras is described by these two facts:
1. Earth's atmosphere was likely a mix of methane, ammonia, and other gases which would be
toxic to most life on our planet today.
2. Life (bacteria) first appeared on Earth.

coconut why: has water in it : )

the index of refraction of the second medium is higher. i just took the test trust me !

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.

substitution is the answer in this case