Based on Acanthostega fossils, scientists now believe that the earliest tetrapods were
A) fully terrestrial.
B) amphibians that used their limbs to drag themselves over the land from one water hole to another.
C) fish that used their limbs to raise themselves out of the water to get gulps of air for oxygen.
D) reptiles that resembled crocodiles.
Answer: C
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Which of the following is a component of the spore—or zygote—wall (in mosses, ferns, gymnosperms, and angiosperms) and helps prevent the desiccation of these structures?
A. sporangium B. sporopollenin C. chitin D. peptidoglycan E. sporangia
The cell cycle is a series of events a cell undergoes as it prepares to
A) divide. B) die. C) adhere to another cell. D) pass along a signal.
The most commonly used unit for measuring cell size is a ____
a. decimeter (dm) b. centimeter (cm) c. millimeter (mm) d. micrometer (?m) e. nanometer (nm)
Habituation can best be described as a form of _____
a. fixed action b. learned behavior c. stereotyping d. instinctual response e. observational learning