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Which group of vertebrates was the first to evolve an amniotic egg, allowing the group to completely break its tie to water?

Suppose a hard frost in southern Florida wipes out nearly all of a population of plants. Even though the plant population recovers in numbers after a couple of decades, the genetic variation within that population remains much reduced. Which is the most likely cause of the diminished genetic variation?

The ultimate origin of genetic variation is

Which of the following groups possess xylem?

The Isthmus of Panama cut off gene flow between Atlantic and Pacific populations of a species of fish. The cessation of gene flow led to the accumulation of genetic differences between the populations, which then led to reproductive isolation. Now, Atlantic and Pacific populations of this fish are separate species that cannot interbreed, even if they were again to come into contact with each other. The process described here is that of

The sporophyte of a vascular plant is nutritionally _______; the sporophyte of a nonvascular plant is nutritionally _______.

At which step in the diagram are gametes being formed?

The blastopore is a structure that first becomes evident during:

Which of the following groups has a water vascular system?

When an isotope releases gamma radiation the atomic number