A large asteroid or comet impacted the earth.
Answer:
5. Gregor Mendel
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a) ribosomes on the rough endoplasmic reticulum
mRNA (created by DNA) leaves the nucleus through the nucleic pores, and from there will enter a nearby ribosome since the rough endoplasmic reticulum is surrounding the nucleus. It is there that polypeptides are made and transported in vesicles to the Golgi apparatus because they cannot touch the cytoplasm when still incomplete. Hope this helped.