Scientists hypothesize that a major factor promoting the adaptive radiation of mammals was probably
A) their development of fur.
B) the mass extinction of most dinosaurs.
C) internal fertilization.
D) the origin and diversification of flowering plants.
Answer: B
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Pollen requires all of the following to germinate
EXCEPT a. contact with epidermal cells of the stigma b. binding to the stigma by species specific adhesion proteins c. nutrients to diffuse into the dry pollen d. metabolism to begin in the two cells in the pollen grain e. all of these are required
A human male diploid cell has which sex chromosome combination?
a. XX b. XY c. YY d. X e. Y
Avery, MacLeod, and McCarty (1944) demonstrated that DNA was the genetic material by treating heat-killed Streptococcus pneumoniae S (smooth) strain with DNase,
thereby preventing transfer of the "transforming substance" from the killed S strain to the live R (rough) strain when the two were mixed together and injected into mice. Another way that one could demonstrate transformation in bacteria would be to extract DNA from A) an R strain and mix it with cells of an S strain. B) both S and R strains and mix it to allow recombination to take place. C) an ampicillin-sensitive strain and mix it with cells of an ampicillin-resistant strain. D) an S strain and mix it with cells of an R strain. E) None of the above are correct.
What is hemoglobin?
A. A reliable source of oxygen B. A protein that is colorless when deoxygenated C. An iron-containing respiratory protein D. A protein found in invertebrates such as crabs and octopus E. A by-product of gas exchange