Down syndrome in humans is due to

A. two Y chromosomes.
B. trisomy (three copies of chromosome 21).
C. three X chromosomes.
D. monosomy (one copy of chromosome 21).


Answer: B

Biology & Microbiology

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A major chemical used to preserve meat products is ________.

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Which reefs are directly impacted by human activity the most?

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Answer the following statements true (T) or false (F)

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This animal is radially symmetric, has

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a. a jellyfish b. an earthworm c. a sea anemone d. a sponge e. more than one of these

Biology & Microbiology