Down syndrome results from which of the following chromosomal abnormalities?
a) a truncated copy of chromosome 3
b) all or part of a third copy of chromosome 21
c) translocation of genetic material on chromosome 21
d) the absence of a second copy of chromosome 10
e) two Y chromosomes
Ans: b) all or part of a third copy of chromosome 21
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The central nervous system first forms during
A. fertilization. B. cleavage. C. neurulation. D. gastrulation. E. organogenesis.
Why are contaminants such as TCEs and PCBs so difficult to remove using traditional methods?
A. They easily adsorb onto organic matter in the environment. B. They are too toxic to be safely handled. C. They naturally degrade into harmless forms that cannot be distinguished from the natural chemical makeup of the environment. D. They are so volatile they escape into the atmosphere so they're impossible to contain.
When humans are developing in utero they have characteristics that are not found in the fully developed infant. Which type of homology does this typify?
A. Structural. B. Molecular. C. Developmental. D. Both developmental and vestigal. E. Vestigal.
You are a medical microbiologist in Dallas, TX. A small population of individuals spread throughout the city have been experiencing alarming yet similar symptoms affecting the liver that have physicians puzzled as to the etiology, although they all suspect it is microbial in nature. What steps would you take to elucidate the organism?
A. 1. Biopsy the patient's liver to look for organisms; 2. Culture the organisms obtained from the liver and run biochemical tests to determine similarities to other known liver pathogens; 3. Inoculate liver pathogens into lab animals to compare symptoms. B. 1. Sample the livers from affected patients to culture and compare organisms; 2. Grow the suspected organisms in culture; 3. Inoculate the cultured organisms into a laboratory animal and monitor for similar symptoms; 4. Culture and analyze the organism from the lab animal and determine relatedness. C. 1. Inoculate all suspected organisms into a laboratory animal and monitor for similar symptoms; 2. Biopsy the original patient's liver to look for organisms; 3. Grow the suspected organisms from the liver in culture; 4. Culture and analyze the organism from the lab animal and determine relatedness. D. Sample the livers of all sick individuals and culture the organisms, comparing symptoms and microscopic characteristics.