The mass extinction at the end of the Cretaceous period:a
occurred about 250 million years ago.
b. had little impact on gymnosperms.
c. was likely the result of dramatic climate changes.
d. was followed by the period dominated by reptiles and dinosaurs.
e. was caused by the global distribution of iridium and the subsequent radioactive fallout.
C
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There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then hair is a shared _____
A) derived character of mammals, even if cynodonts continue to be classified as reptiles B) derived character of the amniote clade and not of the mammal clade C) ancestral character of the amniote clade, but only if cynodonts are reclassified as mammals D) derived character of mammals, but only if cynodonts are reclassified as mammals
Which of the following is a "cost" associated with sexual reproduction?
a. other than mutation, no new genetic diversity in the next generation b. requires time/energy to find/court mat c. only females can produce offspring d. disruption of beneficial allele/trati combinations e. none of the aboves are costs associated with sexual reproduction
Which element is most particularly associated with organic chemistry?
A. carbon B. sulfur C. nitrogen D. hydrogen E. oxygen
Iron is considered an essential element for many bacteria. Based on the animation, how would lack of iron affect energy production of a bacterium?
a. Lack of iron would mean lack of heme, and thus lower amounts of functioning cytochrome proteins. This would mean lower energy yields. b. Lack of iron would mean that most of the oxygen could be reduced to form water, improving energy yields. c. Lack of iron would not have any affect on this system.