Restriction endonucleases in bacteria may have evolved in order to
A. protect the bacteria from infection by viruses.
B. carry out natural genetic engineering.
C. use nucleic acids as a food (energy) source.
D. All of the choices are correct.
Answer: A
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What important feature(s) of noncovalent bonds makes them so important to life?
A. They are strong bonds that hold atoms together tightly in cells. B. They are weak in a cellular environment so they can be made, broken, and reformed easily. C. They can only occur in cells. D. Both a & c. E. Both b & c.
Harry Noller's experiments in which he extracted the ribosomal proteins and found that RNA molecules could catalyze
protein synthesis had one major flaw. What was the flaw?
a. the extraction process may have altered the RNA molecules b. protein synthesis may have occurred prior to extraction c. coenzymes, which were not extracted, might have been responsible for the reaction d. the extraction process may have altered the pH of the environment e. undetectable amounts of protein may have remained
In the blood clotting process, platelets arrive at the site of damage and start secreting substances to attract more platelets. More platelets arrive at the site and secrete attractants to recruit more platelets. This is an example of:
A. positive feedback. B. negative feedback. C. electrical signaling. D. feedforward regulation.
The splitting of water in photosynthesis provides:
A) hydrogen ions and light energy. B) O2 and electrons. C) CO2 and electrons. D) glucose and electrons.