Drugs can cross the blood-brain barrier only if they are
a) large-molecular-weight molecules.
b) small-molecular-weight molecules.
c) water-soluble.
d) lipid-soluble.
Ans: d) lipid-soluble.
You might also like to view...
In Connell's experiments with the barnacles Chthamalus stellatus and Semibalanus balanoides, the potential distribution of each species, in the absence of the other, is known as the
A. competition zone. B. idealized niche. C. fundamental niche. D. tidal boundary. E. realized niche
Small quantities of hormone can result in profound responses in target tissues. This type of response is referred to as
a. amplification b. a first messenger response c. a gene activation response d. a neural response e. a growth factor response
In the studies by David Tilman of the University of Minnesota and John Downing of the University of
Iowa, reported in the journal Nature in 1994, they established and monitored 207 plots of Minnesota grasslands for seven years. During the study period, Minnesota's worst drought in 50 years occurred (1987-1988). The ecologists found that those plots with the greatest number of plant species lost __________ ground cover, as measured by dry weight, and recovered faster than species-poor plots. a. less b. more c. no detectable d. only deciduous e. detectable
Which cells form flexible support strands such as the "strings" in celery?
a. sclerenchyma cells b. tracheids cells c. collenchyma cells d. parenchyma cells