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: A.
Explanation:
Cells generally have a relatively short lifestyle in that they grow, divide and then die off. This is not the case with cancerous cells as those ones mutate and then multiply such that they eventually form a tumor.
Looking at the graph, most of the cells are remaining at a lower or manageable number because they are dying off. Cell A on the other hand is simply increasing in number which means that it is a cancerous cell as it is increasing its number by mutating instead of dying off like other cells would.
Blood flows to the brain through the internal carotid and vertebral arteries and away from the brain through the internal jugular vein. The internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as the face, skull, scalp and the meninges. The vertebral arteries provide supply to the upper spinal cord, brainstem, cerebellum, and the posterior part of the brain.
Answer: the purpose is to help eliminate harmful germs or bacteria and can help prevent food-borne illness.
What person? You might want to send a picture or something.
