Explain why geneticists believe that almost all chromosomally abnormal embryos and fetuses are eliminated as
pregnancy progresses. What will be an ideal response?
ANSWER: Comparison of the number of chromosomal abnormalities detected by CVS (performed at 8
to 10 weeks of gestation) versus amniocentesis (at 16 weeks of gestation) shows that the
abnormalities detected by CVS are two to five times more common than those detected by
amniocentesis, which in turn are about two times more common than those found in
newborns. This decrease in the frequency of chromosomal abnormalities during pregnancy
provides evidence that almost all chromosomally abnormal embryos and fetuses are
eliminated as pregnancy progresses.
You might also like to view...
A silent mutation is a mutation that only occurs in noncoding regions of DNA
A. true B. false
All of the following nucleotide bases are pyrimidines EXCEPT
A. adenine. B. thymine. C. cytosine. D. uracil. E. cytosine and thymine.
Trichomoniasis is the primary nonviral sexually transmitted disease worldwide. One complication of this infection is:
a. keratitis. b. endometritis. c. meningitis. d. appendicitis.
During which stage of syphilis does fever, lymphadenopathy, and a red to brown rash occur?
A. Latent B. Tertiary C. Primary D. Secondary