Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection when injected into mice, and a second that is harmless
He observed that pathogenic bacteria that have been killed by heating can no longer cause an infection. But when these heat-killed bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a mouse. What did Griffith conclude from this experiment?
(a) The infectious strain cannot killedby heating.
(b) The heat-killed pathogenic bacteria "transformed" the harmless strain into a lethal one.
(c) The harmless strain somehow revived the heat-killed pathogenic bacteria.
(d) The mice had lost their immunity to infection with S. pneumoniae.
(b)
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In DNA replication there are leading and lagging strands, because
A) DNA replication is conservative and a completely new DNA molecule must be made. B) DNA replication is semiconservative and each strand is copied simultaneously in opposite directions. C) the strands of DNA are parallel and are copied in the same direction simultaneously. D) one strand of DNA is copied faster than the other.
You have 1 L of 2 mM uric acid. Conditions change in such a way that all the uric acid precipitates out of solution. What is the final osmolarity of your solution?
A. 2 mM B. 1 mM C. 1/2 mM D. 0 mM
The name given to the reaction involving addition of electrons or hydrogen atoms to a compound is termed
A. glycolysis. B. reduction. C. oxidation. D. metabolism.
Ammonia is produced when cells break down
a. fats. b. amino acids. c. carbohydrates. d. nucleic acids. e. vitamins.