Answer:
The earliest oxygen-producing life forms were Cyanobacteria. Besides Cyanobacteria, these tiny organisms have another name known as blue-green algae
Explanation:Some scientists think that 2.4 billion years ago is when organisms called cyanobacteria first evolved, which could perform oxygen-producing (oxygenic) photosynthesis. Other scientist think that cyanobacteria evolved long before 2.4 billion years ago but something prevented oxygen from accumulating in the air
An increase in finite resources
A) The DNA replicates, producing two copies of each chromosome.
Pepsin (D.)
Pepsin is an enzyme that break down protein to make smaller peptide, in other words, they break up polypeptidae into peptide.
Hope it helped,
BioTeacher101
D). Many different experiments are performed and repeated.
