Name a difference between a vein and artery

Describe the iron sulfide hypothesis and the lipid membrane hypothesis.

Which of the following would most likely be key to gathering evidence that the rna world hypothesis is valid? creation of suitable environments for long-term study of single-celled organisms simulation of early earth conditions and long-term study of the resulting molecules development of a system for studying the microsphere's ability to absorb additional molecules categorization of the different specific conditions that result in the development of microspheres

Galaxy whose shape seems different follow no set pattern are classified as