Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement but one (extra) chromosome 21. Although fertility is reduced in both sexes, females have higher fertility than males. Van Dyke et al
(1995; Down Syndrome Research and Practice 3[2]:65—69 ) summarize data involving children born of Down syndrome individuals. Given the fact that conceptuses with 48 chromosomes (four chromosome 21's) are not likely to survive early development, what percentage of surviving offspring would be expected to have Down syndrome if both parents have Down syndrome?
A) One-half of the surviving offspring would be expected to have Down syndrome.
B) All the children would be expected to have Down syndrome.
C) One-third of the surviving offspring would be expected to have Down syndrome.
D) None of the surviving offspring would be expected to have Down syndrome.
E) Two-thirds of the surviving offspring would be expected to have Down syndrome.
E
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Which of the following is likely required to initiate cell differentiation during development?
A. cell division B. the presence of certain mRNAs needed for expression of cell-specific proteins C. the buildup of cell-to-cell adhesion molecules D. the presence of carbohydrates E. hydration of the egg during fertilization
3-phosphoglycerate is to C3 plants as ________ is to C4 plants
Fill in the blank with correct word.
Marine annelids (polychaetes) are different than earthworms in that polychaetes
A. have paddle-like parapodia that earthworms do not have. B. marine annelids have a well developed coelom, whereas earthworms do not. C. lack the setae that earthworms have. D. lack a larval form, whereas earthworms have a larvae form. E. have segments, whereas marine annelids do not.
states Page 61that all organisms are composed of cells, the smallest units of living matter and that new cells come only from preexisting cells.
What will be an ideal response?