The ascending portion of the loop of Henle is
A. impermeable to water and permeable to sodium.
B. permeable to water and impermeable to sodium.
C. the site of active transport of water.
D. permeable to water and permeable to sodium.
E. impermeable to water and impermeable to sodium.
Answer: A
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Mammals lose unwanted solutes through
a. urinary excretion only. b. respiration only. c. muscle contraction only. d. respiration and urinary excretion. e. lymph filtering only.
Select the correct sequence of vertebrate development beginning with fertilization.
A. fertilization ? cleavage ? gastrulation ? neurulation ? organogenesis ? neural crest formation B. fertilization ? gastrulation ? cleavage ? neurulation ? neural crest formation ? organogenesis C. fertilization ? neurulation ? gastrulation ? organogenesis ? neural crest formation ? cleavage D. fertilization ? gastrulation ? neurulation ? neural crest formation ? cleavage ? organogenesis E. fertilization ? cleavage ? gastrulation ? neurulation ? neural crest formation ? organogenesis
The monomer of tubulin:
a. Has 3 subunits in it b. Is a monomer with a molecular weight of 42 kDa c. Is a dimer with a molecular weight of 220 kDa d. Is a heterodimer with a total molecular weight of 110 kDa e. None of the above
Biologists have discovered the kingdom Protista to be paraphyletic. Which of the following statements is true, and consistent with this conclusion?
A) Various combinations of prokaryotic ancestors gave rise to different lineages of protists. B) Animals, plants, and fungi arose from different protistan ancestors. C) Multicellularity has evolved only once among the protists. D) Chloroplasts among various protists are similar to those found in prokaryotes. E) The protists arose from a common ancestor that was a parabasalid.