Down syndrome is caused by a(n)
a. dominant lethal gene.
b. chromosomal aberration.
c. extra Y chromosome.
d. deletion of genetic material in chromosome 21.
e. a homozygous recessive gene.
Answer: b. chromosomal aberration.
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In studies of the differences in men's and women's brains, which of the following statements is FALSE?
a. No physical differences between male and female brains have been found. b. When presented with a language task, both men and women showed increased activity in Broca's area. c. During the language task, both the left and right brains were activated in more than half the women tested. d. Men and women performed equally well on a task that involved sounding out words.