Which of the following is not largely secreted
by the gonads?
a. estrogen.
b. testosterone.
c. progesterone.
d. all of these.
e. none of these
D
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What is the complement DNA strand to 5?-ATTCGGTGA-3??
A. 5?-TAAGCCACT-3? B. 3?-CGGATTGTC-5? C. 5?-CGGATTGTC-3? D. 3?-TAAGCCACT-5? E. 3?-ATTCGGTGA-5?
In opsonization with IgG, why would it be important that IgG react with the antigen BEFORE a phagocytic cell recognizes the antibody molecule?
A. If the IgG is bound to the phagocyte BEFORE opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen (it would be "naked," so to speak). B. Binding of IgG by phagocytes would block the antigen binding sites on the IgG molecules, preventing them from binding to the microbes. C. Binding of IgG by phagocytes changes their conformation-and by changing their protein conformation, their antigen binding sites are changed and they can no longer recognize their specific antigenic epitopes. D. Binding of antibody by phagocytes results in immediate release of protein-destroying enzymes to the outside of the cell. Since antibodies are proteins, they would be destroyed by these enzymes (and would then be unable to bind to their specific antigenic epitopes).
The rate of diffusion through a semipermeable membrane will be lowest when the
a. differences in concentration on either side are the greatest. b. temperature is raised to near boiling. c. differences in concentration on either side are the least. d. actions of active transport override diffusion. e. inside is hypertonic to the outside.
Extracellular ground substance is composed of
a. liquid proteins. b. lipids. c. polysaccharides. d. fibrous proteins. e. specialized cells