Which body system develops first in a human embryo?

A. nervous
B. excretory
C. reproductive
D. respiratory
E. circulatory


Answer: A

Biology & Microbiology

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Many species of angiosperms are self-incompatible due to the presence of the ____ -gene

Fill in the blank with the appropriate word.

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Multiple operons may be controlled by ________ or ________.

Fill in the blank(s) with the appropriate word(s).

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Demographic studies include all of the following except what? 

A. age structure B. growth rates C. mortality and survivorship curves D. sex ratio E. measurements of interspecific competition

Biology & Microbiology

All gills

a. consist of overlapping rows of filaments. b. are external. c. are paired. d. are associated with a blood transport system. e. fit all of these descriptions.

Biology & Microbiology