The movement of molecules across a membrane from an area of higher concentration to an area of lower concentration with the use of a carrier molecule embedded in the membrane is called
A. passive diffusion.
B. active transport.
C. facilitated diffusion.
D. osmosis.
Answer: C
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Unattached earlobes (EE or Ee) are described in the textbook as dominant over attached earlobes (ee). A couple both have unattached earlobes. Both notice that one of their parents on both sides has attached earlobes (ee). Therefore, they correctly assume that they are carriers for attached earlobes (Ee). The couple proceeds to have four children.
A. The children must repeat the grandparents' genotype (Ee). B. If the first three are heterozygous, the fourth must be homozygous recessive. C. Two heterozygous, one homozygous recessive, and one homozygous dominant is a likely outcome, but all heterozygous, or two, three, or all four homozygous are also possible. D. They can be certain that three will be heterozygous and one homozygous recessive. E. All children must have unattached earlobes since both parents possess the dominant gene for it.
Drug resistance to anti-HIV drugs is a serious problem. Why does drug resistance appear so rapidly in HIV?
A) It has a high rate of mutation. B) It's a virus. C) It's found in the blood. D) It's sexually transmitted.
Membranes that do not contain glands are called
A. espiratory B. serous C. dense D. mucous
Atherosclerosis is characterized by
a. increased circulation to the heart b. larger muscles c. a narrowing of the inner walls of coronary arteries due to buildup of fatty materials d. a widening of inner walls of blood vessels as a result of a heart attack