Since the Pleistocene ice age, deserts have been gradually forming in the southwestern United States. As the original lakes and rivers of this area shrank into isolated streams and springs, the fishes living in them developed a strong potential for:
A) hybrid inviability. B) temporal isolation. C) hybrid sterility. D) speciation.
Answer: D
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In mammals, the nuclei resulting from the union of the sperm and the egg are first truly diploid after the _____
A) acrosomal reaction B) completion of spermatogenesis C) initial division D) activation of the egg E) completion of gastrulation
Which is true about protein A?
A. It binds to the Fc region of antibody. B. It hides bacteria from phagocytes. C. It enhances binding of phagocytes. D. It digests antibodies. E. It binds to the Fc region of antibody AND it hides bacteria from phagocytes
This chordate has a four-chambered heart, no
bladder, the males typically have no penis, and no teeth. This animal is
a. a bird. b. a crocodile. c. a bat. d. a frog. e. a shark
Which of the following is best observed by using a compound light microscope?
A. A eukaryotic cell B. a virus C. A DNA sequence D. The inner structure of a mitochondrion E. A nuclear pore