One trend in the evolution of animals is the increase in the number of tissue (germ) layers during embryonic development. Flatworms and more complex animals have ________ layers
A) two B) three C) four D) five E) six
B
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During transcription which strand will act as the template for coding? a. The DNA strand
b. Both can be used as a template. c. The RNA strand. d. Neither is used as a template. e. None of these choices.
Plant cells called ____ form flexible support strands such as the "strings" in celery
a. sclerenchyma b. tracheids c. collenchyma d. parenchyma e. vessel members
In which of the following plants is the
gametophyte larger and longer-lived than the sporophyte?
a. mosses b. conifers c. ferns d. flowering plants e. none of these
Besides the obvious fact that chemical mutagens are dangerous to handle, another major disadvantage to their use is that __________
A) most of these mutations are immediately lethal B) most chemically induced changes are detectable only by sequencing C) chemical mutagens activate transposons D) two or more generations of further matings are required to isolate them E) they alter all A-T and C-G base pairing