Which of the following is most likely the cause of the current extinction crisis?
a. asteroid impact
b. human activity
c. adaptive radiation
d. tectonic activity
e. rising sea levels
ANSWER: b
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In transformation, cells
a. take up pieces of DNA that are released as other cells disintegrate. b. take up pieces of DNA through infection of a virus. c. replicate DNA molecules. d. make replicate copies of one another. e. generate their own DNA.
When conditions do not favor growth of Chlamydomonas, ________ are formed
a. haploid (+) and (-) cells b. diploid immobile spores c. haploid flagellated spores d. zygotes
Why does the sarcomere get narrower during muscle contraction?
A. The myosin fiber shrinks. B. The myosin and actin fibers overlap more. C. The edges of the muscle push the cells closer together. D. The actin fiber shrinks. E. The sarcoplasmic reticulum empties.
Which of the following is an example of predation?
A) a lizard's camouflage B) a hawk swooping down quickly to capture, kill, and eat a prairie king snake C) a goldfinch feeding on the seeds of a thistle plant D) the vivid colors of the poison-arrow frog in Costa Rica E) mechanical devices, such as quills in a porcupine