Theories on the atmosphere of early Earth indicate that it lacked
A) H2. B) NH3. C) H2O. D) CH4. E) O2.
E
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What are some nonscience job opportunities in a biotechnology company? Why would it still be useful to have some science background for these positions?
What will be an ideal response?
Label the leaf arrangements as opposite, whorled, or alternate. 
A. ________B. ________C. ________
What will be an ideal response?
Estimates of earth's carrying capacity for humans vary from about 0.6 billion to several tens of billions.
a. true b. false
Which type of proteins are involved in nutrient transport across the plasma membrane and why?
A) integral proteins, because they span the membrane and are able to carry nutrients across the membrane B) integral proteins, because they are smaller and can travel across the membrane, thereby carrying nutrients across the membrane C) peripheral proteins, because they are smaller and can travel across the membrane, thereby carrying nutrients across the membrane D) receptor proteins, because their carbohydrate chains bind to nutrients and carry them across the membrane E) peripheral proteins, because they span the membrane and are able to carry nutrients across the membrane