Which of the following choices best describes gated transporters?
a. Gated transporters are channels or pores in the membrane that are always open
b. Gated transporters expend energy to move molecules against concentration gradients.
c. Gated transporters change shape in response to binding or charge, releasing the molecule on the other side.
d. Gated transporters move two substances across the membrane in opposite directions.
c
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Which is not a component of innate immunity?
A. Skin B. Inflammation C. Fever D. Antibody
The single-celled yeast, Saccharomyces cerevisiae, was used to construct the first eukaryotic artificial chromosome. This was a significant achievement because
A) yeast centromeres are identical to human centromeres. B) it defined chromosomal regions that serve as centromeres and origins of replication in yeast. C) it revealed the rate of DNA replication in yeast. D) it demonstrated that some yeast genes are not essential. E) it defined the chromosomal region with the TRP+ gene for tryptophan synthesis in yeast.
Which type of cell division occurs during growth and repair of tissues?
Statistics show that thirty-four people per thousand enter the population by birth. This is a statement about
A. mortality. B. the stable equilibrium phase of a population growth curve. C. the lag phase of a population. D. natality.