Which of the following is a typical feature of an ATP-driven active transport mechanism?
A) The transport protein must cross to the correct side of the membrane before the solute can bind to it.
B) The transport protein is irreversibly phosphorylated as transport takes place.
C) The transport protein catalyzes the conversion of ADP to ATP.
D) The solute moves against the concentration gradient.
Answer: D
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What is the tonicity of the urine of marine mammals compared with another fluid?
a. hyperosmotic, compared with seawater b. hypoosmotic, compared with seawater c. isoosmotic, compared with their body fluids d. hypoosmotic, compared with their body fluids
Which of the following is associated with mitosis?
A. Fertilization B. Body cells C. Sexual reproduction D. Sperm and egg E. Germ cells
T cell receptors recognize ______, distinguishing cells that belong to the body from infected body cells.
A. antigens B. MHC markers C. antigens and MHC markers D. complement E. cytokines and complement
Citrus fruit has always been distributed from areas where the fruit is grown to other parts of the country, often by train. In the early 1900s train cars were heated with coal, and it was believed that this heat helped ripen the fruit. Imagine the
surprise of growers and suppliers when fruit that arrived in new boxcars heated by steam arrived unripe. Why did the fruit no longer ripen? A) The length of time needed to ripen the fruit was met by slow-moving older trains; newer steam-powered locomotives arrived before the fruit ripened. B) Ethylene, a by-product of coal burning, ripened the fruit in the cars with the coal stove but was absent from the steam-powered trains. C) The light from the coal-burning stoves caused the fruits to experience short nights, so without this light, they no longer ripened. D) The steam prevented the buildup of abscisic acid, which is needed to ripen fruit.