According to the fossil record, how long ago do scientists believe life on Earth first appeared?

Which short-term environmental change is most likely to lead to ground shifting, landslides, and the collapse of buildings or roads? forest fires flooding earthquakes

Which to produce involved from a symbiotic relationship of organisms which resulted in eukaryotic organisms contain chloroplast

Pls me i need this ! each cell has genes activated depending on it's job and what kind of cell it is. it is the presence of that causes the repressor protein to fall off and unblock the gene on the lac operon. if a gene is turned on then it is being an additional circular chromosome found in some bacteria that is used in genetic engineering.