The answer is 20. Duplicated chromosome has two sister chromatids, identical copies of the chromosome. These two chromatids are joined at the region called centromere. Therefore, one duplicated chromosome has one centromere and two sister chromatids. If there are 20 duplicated chromosomes in a cell, there will be 20 centromeres.
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The world's largest passenger jet, Airbus A380, landed for the first time Monday afternoon at DFW International Airport. (Published Tuesday, Sept. 30, 2014) The largest passenger jet in the world, the Airbus A380, landed Monday at Dallas-Fort Worth International Airport, completing the longest currently flown nonstop route in the world.