Explain why only anaerobic bacteria inhabited Earth for the first two billion years of its existence
What will be an ideal response?
Answer: The key idea is an anoxic environment will not allow aerobic organisms to survive.
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Both extremes of an array of phenotypes are favored in _____ .
A. directional selection B. genetic drift C. gene flow D. disruptive selection E. stabilizing selection
The humoral immune response is delivered by
A. antibodies. B. T cells. C. lymphokines. D. antigens.
Neonatal conjunctivitis differs from non-neonatal conjunctivitis in that
A. neonatal conjunctivitis can be caused by Chlamydia trachomatis, Neisseria gonnorhoeae, or any number of viruses. B. it is transmitted during birth and occurs only in neonates less than 4 weeks old. C. neonates have immune privilege, and are therefore more susceptible to all types of infection. D. it cannot be prevented as the causative organisms are normal microbiota for the mother.
Which is the correct series of events in the evolution of life on Earth?
A) O2 ? aerobic metabolism ? photosynthesis B) Photosynthesis ? O2 ? aerobic metabolism C) Aerobic metabolism ? photosynthesis ? O2 D) O2 ? photosynthesis ? aerobic metabolism