Each DNA strand has a backbone that consists of alternating _____
a. amino acids
b. nitrogen-containing bases
c. hydrogen bonds
d. sugar and phosphate molecules
e. types of sugars
ANSWER: d
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All of the following are true of the natural killer cells
(NK cells) EXCEPT that they a. are most active in innate responses. b. are central to adaptive immunity, like B and T cells. c. alert the immune system to the presence of antigens. d. kill weakened or dying body cells. e. combat viral infections and cancer.
Catabolite repression refers to the repression of the lac operon in the presence of which catabolite?
What will be an ideal response?
What type of blood vessel is solely responsible for exchange between the blood and the interstitial fluid?
A) artery B) arteriole C) capillary D) venule
Of the following fermentation pathways, which can be carried out by human muscle cells?
A) alcoholic B) butanediol C) lactic acid: homolactic D) lactic acid: heterolactic E) mixed acid