Which of these events occurred during the precambrian time?

cyanobacteria filled the water and air with oxygen.

early humans began to make tools, harvest plants, and make cave paintings.

pangaea, the super continent, was formed.

pangaea began to break apart into many continents separated by shallow seas.

Cyanobacteria. The Cambrian explosion wouldn’t have happened without so much oxygen that the Cyanobacteria created

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.

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.