In the United States, most thyroid disorders are
caused by
a. iodine deficiency.
b. iron deficiency.
c. an autoimmune disorder.
d. insecticides.
e. a combination of more than one of these
C
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Cells communicate with each other by various mechanisms. All of the following are examples of ways
cells communicate EXCEPT ____.
a. gap junctions b. transfer chain proteins c. recognition of specific membrane surface molecules d. cell adhesion molecules e. chemical messengers
What types of cells perform cell division?
a. prokaryotes only b. eukaryotes only c. both prokaryotes and eukaryotes d. neither prokaryotes, nor eukaryotes
A species of archaea, Ferroplasma acidarmanus, lives in water and has a pH of zero, yet are able to maintain their internal pH at a cozy 5 despite living in an environment with a composition essentially the same as hot battery acid. These data showing the pH profiles of four enzymes isolated from F. acidarmanus indicate that optimal enzyme function occurs at
1.around pH 5, which is consistent with the organism’s internal environment.
2.around 0, which is consistent with the external environment.
3.an average of around pH 2.5.
4.a fairly basic pH.
What are the two major types of chromosomes in many eukaryotic organisms?
a. sex and non-sex b. XY and ZZ c. sex and autosomes d. autosomes and ZZ