How do we know that the atmosphere of the earth experienced an increase in O2 and became oxidizing between 2.5 and 2 billion years ago?
What will be an ideal response?
The oxygen reacted with the iron ions in the seawater, causing them to form insoluble iron oxides, which built up great iron ore deposits on the ocean floor.
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Which of the following reproduce by binary fission?
A. bacteria B. archaea C. chloroplasts D. mitochondria E. All of these choices are correct.
Activity of the two halves of the cerebrum is coordinated by means of the __________ that connects
them. Neural Control 293 Fill in the blank(s) with the appropriate word(s).
Joan and her doctor notice a suspicious lump in her breast. Joan also has a family history of breast cancer. Which of the following is not a likely next step as they work to determine the cause of the lump?
A. performing a diagnostic mammogram B. genetic testing for mutations in the BRCA1 gene C. taking a biopsy of the lump to look for the presence of cancer cells D. performing a mastectomy to remove all breast tissue in that breast
A significant difference between Neanderthals and modern humans is that Neanderthals:
A) were taller. B) used throwing spears. C) were foragers, not "collectors." D) had smaller brains.