In the Hershey and Chase experiment, the pellet was radioactive after bacteria had been infected with
32P-labeled viruses and centrifuged. Why?
a. Bacteria were centrifuged to form the pellet, and they had incorporated radioactive
proteins into their DNA.
b. Bacteria were centrifuged to form the pellet, and they had incorporated radioactive DNA.
c. Viruses were centrifuged to form the pellet, and they had incorporated radioactive proteins
from the bacterial DNA.
d. Bacteria were centrifuged to form the pellet, and they had incorporated radioactive
proteins into their cell membranes.
e. Viruses were centrifuged to form the pellet, and they had incorporated radioactive DNA.
B
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A nepron
a. is a kidney tubule. b. cleanses the blood. c. forms urine. d. connects the kidneys to the bladder. e. is all of these except d.
Four of the following statements about crocodilians are true. Which statement is false?
a. They live in or near water. b. They are predators with sharp teeth. c. They have a two-chambered heart. d. They have powerful jaws. e. They are the closest living relatives to birds.
Four of the five choices listed below are prokaryotic
structures. Select the exception. a. ribosomes b. cell wall c. pili d. endomembrane system e. nucleoid
Why do mammals adapted to dry climates tend to have considerably more long-looped nephrons than those adapted to wet climates?
A) So that their blood pressure does not drop to dangerously low levels during periods of drought B) So that a lower concentration of salt can be produced in the interstitial fluid of the kidney medulla, causing less water to be reabsorbed into the capillaries C) So that the wastes can be excreted as uric acid instead of urine D) So that the excess urea they produce as a result of dehydration can be properly filtered by the nephrons and excreted E) So that a higher concentration of salt can be produced in the interstitial fluid of the kidney medulla, causing more water to be reabsorbed into the capillaries