Which of the following is the most likely series of events?
A. Earth formed—oxygen in atmosphere—living organisms—ozone
B. Ozone—living organisms—plants—organic molecules
C. Organic molecules—ozone—living organisms—oxygen in atmosphere
D. Organic molecules—living organisms—oxygen in atmosphere—ozone
D. Organic molecules—living organisms—oxygen in atmosphere—ozone
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During the first major divergence of life the
atmosphere was a. high oxygen, high carbon dioxide. b. high hydrogen, low oxygen. c. changing from anaerobic to aerobic. d. firmly in the age of aerobes. e. all of these.
How could an embryonic stem cell be used to repair a severed spine?
A) Embryonic stem cells secrete proteins that repair all other cell types, including nerve cells. B) Embryonic stem cells can grow into any other cell type, including a nerve cell. C) Embryonic stem cells can cause any other cell type to multiply. D) Embryonic stem cells are primarily involved with neural growth and development.
According to the fossil record, the most ancient group of fungi is probably the
A) glomeromycetes. B) chytrids. C) basidiomycetes. D) zygomycetes. E) ascomycetes.
Microevolution involves ________
A. changes in a population's gene pool. B. a change in the ratio of males to females in a population. C. the fixation of an allele over a long period of time. D. changes to the number of individuals in a population.