Oxygen was absent in Earth's early atmosphere. When oxygen levels rose in the atmosphere, what likely occurred? A. Some life went extinct.
B. Some life survived in a few habitats without oxygen. C. All of the above.
D. Some life survived because it had adaptations and/or evolved metabolism that used oxygen.

How are the reproductive cycles of a fungus and a pteridophyte similar? a)both organisms form fruiting bodies that produce diploid seeds. b)both organisms produce haploid spores and exhibit diploid and haploid stages. c)both organisms reproduce sexually when two haploid hyphae fuse. d)both organisms exhibit a diploid stage and are only able to reproduce asexually.

Why is it incorrect to say that mitochondria function only as energy factories with cell

Is there any solid scientific evidence that humans have been cloned?