Which proteins form channels in the membrane that allow selected polar molecules and ions to pass through and
across the membrane?
a. transport proteins
b. recognition proteins
c. receptor proteins
d. cell adhesion proteins
e. nuclear proteins
ANSWER: a
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A) neurotoxins. B) endotoxins. C) ectotoxins. D) superantigen toxins.
The linking number:
A. is negative for most B-form DNAs. B. changes when double-stranded DNA is bent or deformed. C. increases when single-stranded breaks occur in the DNA. D. increases when double-stranded breaks occur in the DNA. E. is the number of times one strand of a closed circular DNA is wound about another.
Refer to the accompanying figure. The function of the structure labeled as 14 is to:
a. stimulate the ventricles to contract.
b. pump blood to the lungs.
c. pump blood into the systemic circulation.
d. receive blood from the systemic circulation.
e. receive blood from the pulmonary circulation.
The condition known as graft-versus-host disease may result after
A) a bone marrow allograft. B) a mismatched blood transfusion. C) a bone allograft. D) a plasmapheresis procedure. E) any type of allograft procedure.