A Gram stain uses a primary dye to stain Gram-positive organisms and a counterstain to dye Gram-negative organisms. What color will a Gram-negative specimen be?

A) clear
B) purple
C) green
D) red


Ans: D) red

Biology & Microbiology

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Racker and Stoeckenius used synthetic phospholipid membrane vesicles that contained a light-activated protein pump

and ATP synthase to test Mitchell's chemiosmotic hypothesis. What was the conclusion of this experiment?

a. Phospholipid membrane vesicles require a proton gradient to maintain integrity. b. ATP synthase is powered by the proton-motive force. c. ATP synthase can generate a proton gradient. d. Light-activated proton pumps can generate a proton gradient. e. Light-activated proton pumps interact with ATP synthase to modulate its activity.

Biology & Microbiology

Which of the following statements about progeria is false? a. Progeria arises from a mutation in the gene for lamin

b. Progeriacs die of diseases usually seen in the elderly, like stroke or heart attack. c. The symptoms of progeria begin before age two. d. Progeria can run in families because parents may be unaffected carriers.

Biology & Microbiology

What are characteristics of the pedigrees of families with mitochondrial diseases?

A) All children of affected mothers are usually affected regardless of their sex. B) Only the male children of affected mothers are affected, female children are not affected. C) Only female children of affected mothers are also affected, male children are not affected. D) All children of affected males are usually affected.

Biology & Microbiology

How fast a population grows depends only on its birth rate

a. true b. false

Biology & Microbiology