The animal in Figure 21-2 represents:
a.
a mosasaur.
b. an ichthyosaur.
c. a pterosaur.
d. a thecodont.
e. a plesiosaur.
B
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The methylation state of an individual CpG island:
A. is fixed; such genes are permanently turned off. B. is fixed, but this has no effect on whether genes are expressed. C. is randomâ€"sometimes the cytosines are methylated and sometimes they're not, but the state is independent of the environment or cell type. D. can change over time in response to environmental cues, allowing genes to be turned on or off as needed. E. can change over time in response to environmental cues, but this has no effect on gene expression.
Many single-celled eukaryotes that normally exist in a haploid state reproduce asexually by:
A. meiotic cell division. B. binary fission. C. mitotic cell division. D. fusion.
Viruses ____________.
a) sit on the fence between life and nonlife. b) use either DNA or RNA as their genetic material. c) only infect sick people. d) all of the above are correct. e) only a and c
When the diaphragm contracts, the thoracic cavity ________, and you ________
A) gets smaller; exhale B) gets larger; exhale C) gets larger; inhale D) gets smaller; inhale