The period during which the presence of stromatolites decline is the Proterzoic period. Stromatolites are widely distributed sedimentary structures consisting of laminated carbonate or silicate rocks, produced over geologic time by the trapping, binding, or the precipitating of sediment by groups of microorganisms, primarily cyanobacteria.
Answer:
pathogens
Explanation:
pathogens may occur in various way e.g spread from a person to person by directly body contact
Answer:
i
Explanation:
long chains of repeating subunits, called nucleotides
A nucleotide is the basic building block of nucleic acids
