Which of the following statements regarding Down syndrome is INCORRECT?
A. The affected fetus can be detected before birth by means of amniocentesis.
B. The affected child is mentally retarded and usually has a characteristic physical appearance.
C. Cells from an affected child reveal an extra sex chromatin body (Barr body) attached to the nuclear membrane of the cells.
D. Chromosome karyotype of affected child usually reveals trisomy of chromosome 21.
Question 2
The mechanism by which penicillin, cephalosporins, and other beta-lactarn ring antibiotics act against bacteria is
A. They prevent the synthesis of the bacterial cell wall by inactivating the bacterial enzymes that make the cell wall.
B. They disrupt the function of the bacterial cell membrane.
C. They attach to ribosomes of the bacterial cell so that the bacterium cannot make needed proteins.
D. They compete with compounds that the bacterium needs in order to grow and divide, thereby inhibiting or stopping the growth of the bacteria.
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24 weeks old human fetus
The photo shows an ultrasound image of a fetus of about 20 weeks’ gestational age.
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