The lac operon in Escherichia coli
A) prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment.
B) prevents lactose intolerance.
C) prevents lactose-utilizing enzymes from being expressed when lactose is present in the environment.
D) promotes the expression of lactose-utilizing enzymes when lactose is absent from the environment.
Answer: A
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Of the three plants measured in the figure, which requires water to allow sperm to swim to the egg?
A. shrubs
B. All of the plant groups rely on sperm swimming to the egg in water.
D. None of the plant groups relies on sperm swimming to the egg in water.
D. mosses
E. herbs
The planets of our solar system were formed by the collisions of ____.
a. meteors b. asteroids c. comets d. moons e. existing planets
What are the predicted phenotypes of the female children from the union of a woman who is heterozygous for
hemophilia and a man who has normal blood clotting characteristics? (Use the Punnett square to verify your answer.) a. all carriers b. 3 homozygous normal : 1 carrier c. 1 homozygous normal : 1 carrier
d. 1 hemophilia: 2 homozygous; normal : 1 carrier e. all hemophiliacs
Lead is known to undergo biomagnification and accumulate in bones. What do you predict will happen to lead taken up by a tiger after it dies in the wild?
A. The lead will reenter the food web via detritivores and decomposers. B. The lead will be broken down to a non-toxic form. C. The lead will reenter the food web via evaporation and precipitation. D. The lead will be eliminated from the food web because no species prey upon the tiger.