The zona pellucida is

A) a protective layer around the secondary oocyte.
B) a protective layer around the sperm.
C) a bump on the head of a sperm that contains enzymes.
D) the biggest constriction of a chromosome.


A) a protective layer around the secondary oocyte.

Biology & Microbiology

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H. ducreyi requires what special media to grow?

a. Heart infusion–based agar, supplemented with 10% IsoVitaleX and vancomycin b. Mueller-Hinton–based chocolate agar, supplemented with 1% IsoVitaleX and vancomycin c. Heart infusion–based chocolate agar, sup-plemented with 10% fetal bovine serum and vancomycin d. Mueller-Hinton–based agar, supplemented with 10% IsoVitaleX and vancomycin

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The concept of "immune privilege" explains why the central nervous system has

A. a completely different set of immune responses. B. more MHC markers than other tissues. C. a reduced immune response compared to the rest of the body. D. a greater immune response than the rest of the body.

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Parasites have often been described incorrectly as having "devolved" from a more highly evolved organism. Why would it be more accurate to say that they are just as evolved as any other organism?

What will be an ideal response?

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The DO represents the _____ dose for human cells.

a) mean survival b) mean lethal c) 50% survival d) 50% lethal

Biology & Microbiology