When two frog species, Rana pippins and Rana sylvatica, mate, the offspring die early in embryonic development. This is an example of ___________.
A. Hybrid sterility
B. Reduced hybrid fertility
C. Mechanical isolation
D. Reduced hybrid viability
Ans: D. Reduced hybrid viability
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The histocompatibility complex proteins function in
A. antibody proliferation. B. B cell maturation. C. recognition of self. D. T cell maturation.
Retroviruses make __________ by the process of __________
a. RNA copies of DNA; reverse transcription b. DNA copies of RNA; reverse transcription c. genetic probes; Southern blotting d. genetic probes; Northern blotting e. telomerase; mutagenesis
What hypothetical hormone promotes flowering but has never been successfully isolated?
a. florigen b. ubiquitin c. jasmonic acid d. brassinosteroids e. methyl salicylate
Which cells provide flexible support to the growing parts of plants?
A) collenchyma cells B) sieve-tube elements C) sclerenchyma cells D) parenchyma cells