In humans, an extra copy of chromosome 21 typically leads to moderate to severe mental retardation and sterility, as

well as to a greater likelihood of heart defects and other problems. This disorder is known as ____.



a. Turner syndrome
b. Down syndrome
c. cri-du-chat
d. Triple-X syndrome
e. Klinefelter syndrome


ANSWER: b

Biology & Microbiology

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A tidal pattern of two equal high and low tides per day is called a:

a. mixed semidiurnal tide. b. semidiurnal tide. c. diurnal tide. d. spring tide. e. neap tide.

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Ribosomes can catalyze formation of peptide bonds. This supports the hypothesis that _____

a. an RNA world preceded DNA-based genomes b. RNA can hold more information than DNA c. the first protists had RNA as their genetic material d. RNA's only role is that of an enzyme e. protocells contained DNA

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Which one of the following is directly involved in the process of blood clotting?

A) sodium ions B) antigen C) fibrin D) clotting factor XX E) globulins

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The enzyme rubisco is important to the process of

a. catabolism. c. glycolysis. b. fermentation. d. carbon fixation.

Biology & Microbiology