The adjustable ring of muscular tissue that controls the amount of light entering the eye is the:
a. lens
b. cornea
c. pupil
d. iris
e. retina
d
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Which of the following series is arranged in the correct sequence for nitrogen fixation and its subsequent use?
A. atmospheric nitrogen; use of bacterial nitrogenase; production of ammonia; conversion by plants or algae; synthesis of proteins B. atmospheric nitrogen; use of bacterial nitrogenase; conversion by plants or algae; production of ammonia; synthesis of proteins C. atmospheric nitrogen; production of ammonia; use of bacterial nitrogenase; conversion by plants or algae; synthesis of proteins D. atmospheric nitrogen; production of ammonia; use of bacterial nitrogenase; synthesis of proteins; conversion by plants or algae E. ammonia; conversion by plants and algae; production of atmospheric nitrogen; use of bacterial nitrogenase; synthesis of proteins
What happens to an enzyme after it has catalyzed a reaction?
a. it is sent to the proteasome for degradation b. it is inactivated by phosphorylation c. it is inactivated by dephosphorylation d. it releases the cofactor to get a new one ready for catalysis e. it returns to its original state
Ninhydrin is used to test for the presence of lipids
a. True b. False
Spinal nerves:a
contain only sensory neurons. b. contain only motor neurons. c. contain both sensory and motor neurons. d. form ganglia before they enter and exit the medulla. e. are part of the central nervous system.