The most frequently occurring form of Down syndrome results from
A) an extra broken piece of a twenty-first chromosome attaching to another chromosome.
B) an error during the early stages of mitosis.
C) a failure of the twenty-first pair of chromosomes to separate during meiosis.
D) the inheritance of an extra X chromosome.
Answer: C
Psychology
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A child generally says his or her first true word at about
A) six months of age. B) eighteen months of age. C) nine months of age. D) twelve months of age.
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Which part of the PNS projects from only the cranial and sacral portions of the CNS?
A) parasympathetic nervous system B) sympathetic nervous system C) somatic nervous system D) cranial nerves E) autonomic nervous system
Psychology