The Galapagos finches were an important clue to Darwin's thinking about the origin of species. These finches are believed to have descended from a single ancestral species that colonized the Galapagos archipelago, America, over a short period of time. The Galapagos finches differ in their beak shape and size. Different species feed on seeds that vary in size and hardness. Which of the following is the most likely explanation for these patterns?

#Question id: 8773

#Unit 9. Diversity of Life Forms

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient aerobic bacterium and an ancient cyanobacterium?

#Question id: 8774

#Unit 9. Diversity of Life Forms

A large proportion of archaeans are extremophiles, so called because they inhabit extreme environments with high acidity, salinity, and/or temperature. Such environments are thought to have been much more common on primitive Earth. Thus, modern extremophiles survive only in places that their ancestors became adapted to long ago. Which of the following is, consequently, a valid statement about modern extremophiles, assuming that their habitats have remained relatively unchanged?

#Question id: 8775

#Unit 9. Diversity of Life Forms

Use the following information to answer the question. Paulinella chromatophora is one of the few cercozoans that is autotrophic, carrying out aerobic photosynthesis with its two elongated "chromatophores." The chromatophores are contained within vesicles of the host cell, and each is derived from a cyanobacterium, though not the same type of cyanobacterium that gave rise to the chloroplasts of algae and plants. A crucial photosynthetic gene of the cyanobacterium that gave rise to the chromatophore is called psaE. This gene is present in the nuclear genome of the cercozoan, but is not in the genome of the chromatophore. This is evidence of ________.

#Question id: 8776

#Unit 9. Diversity of Life Forms

What kind of evidence has recently made it necessary to assign the prokaryotes to either of two different domains, rather than assigning all prokaryotes to the same kingdom?

#Question id: 8778

#Unit 9. Diversity of Life Forms

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Horizontal lines indicate instances of gene or genome transfer.

A possible phylogenetic tree for the three domains of life.

If the early history of life on Earth is accurately depicted by the figure, then which statement is most in agreement with the hypothesis proposed by this tree?

#Question id: 8781

#Unit 9. Diversity of Life Forms

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Horizontal lines indicate instances of gene or genome transfer.

A possible phylogenetic tree for the three domains of life.

Which of these processes can be included among those responsible for the horizontal components of the figure?