During succession, two plant species become established at different times. Species A is a perennial with roots that secrete chemicals to maintain a distance between members of the species and similar species. Species B is a low-growing annual with nitrogen-fixing bacteria in its root nodules. Which (if either) of these two species most likely appears first during succession, and why?

An imported plant escapes from a greenhouse and begins to grow outdoors. Unnoticed at first, it proliferates and its seeds begin to spread. After several years, it occurs in the wild in several states. The plant grows faster than many native species and is difficult to eradicate. Which is the most likely result of this plant’s introduction into the ecosystem?

A survey of a pond community identified 57 different species that made up the community. This number can best be described as a measure of the community’s

The California sea otter has the world’s thickest fur. The entrapped air provides:

Asbestos, radiation, and ultraviolet light are all examples of _____.

Which is the best example of a coupled human–natural system?

Which BEST describes why it is important for us to understand how things are measured with the SI system?

The island of Madagascar, off the southern African coast, has a highly unique endemic biota. Roughly 170 million years ago, Madagascar was landlocked in the middle of the supercontinent Gondwana. Gondwana eventually split by continental drift, forming Africa, South America, India, Australia, and Antarctica. For the past 88 million years, Madagascar has been isolated, but some new species can still reach the island from the coast of Africa. This suggests that the evolution of Madagascar’s unique biota is

Which organism is not correctly matched with its dispersion pattern?

If both homologous chromosomes of each pair exist in the same nucleus, that nucleus is