Which of the following statements about gap junctions is false?
(a) Gap junctions are made of connexons.
(b) Molecules up to 1000 daltons in molecular mass can move across gap junctions.
(c) Because gap junctions do not allow ions to pass through, they are not used for electrically coupling cells.
(d) Gap junctions can close in response to extracellular signals.
(c)
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Which of the following statements are not true of hormone actions in plants?
A. Most plant hormones are effective in extremely low concentrations. B. Plant hormones influence cell growth and differentiation. C. Plant hormones may alter patterns of gene expression and rates of cell division. D. Plant hormones act independently and do not affect one another's actions. E. Plant hormones play a central role in plant development. Answer Point Value: 1.0 points
Listeria monocytogenes causes over 2,500 illnesses annually in the United States. If it was isolated in two cases, would epidemiological studies be required to determine if the two cases are related?
A) Yes, epidemiological studies would be required to differentiate between two organisms of the same species and formulate an epidemiological explanation. B) No, simply identifying the bacterial species responsible for the outbreak would be enough to formulate an epidemiological explanation.
Answer the following questions true (T) or false (F)
1. The genome of all DNA animal viruses is replicated in the nucleus of the cell. 2. Bacteriophage release is a gradual process in which small numbers are released at a time. 3. Bovine spongiform encephalopathy is an example of a prion disease.
Which elements are required by all cells in the largest amounts?
a. nitrogen, sulfur, iron, and phosphorus b. phosphorus, oxygen, sulfur, and carbon c. carbon, oxygen, hydrogen, and nitrogen d. magnesium, hydrogen, nitrogen, and, iron