During days 8 and 9 after fertilization in humans, ____

a. amnion cleavage begins
b. a blastocyst forms
c. an embryonic disk is formed
d. implantation occurs
e. gastrulation occurs


ANSWER: d

Biology & Microbiology

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Chitinases are examples of ____

a. systemins b. phytoalexins c. PR proteins d. R genes e. heat-shock proteins

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Inversions occur when a portion of a chromosome is ________

a. relocated on a different chromosome b. lost c. repeated two or more times d. oriented in a reversed direction

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Which of the following molecules is the most

common photosynthetic pigment in plants?

a. chlorophyll a b. chlorophyll b c. chlorophyll c d. chlorophyll d e. chlorophyll e

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The ________ zone extends from a depth of 200 to 4000 meters.

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

Biology & Microbiology