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 the 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? A) Among themselves, they should share relatively few ancestral traits, especially those that enabled ancestral forms to adapt to extreme conditions.
B) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the branches of the extremophiles should be shorter than the non-extremophilic archaeans.
C) They should contain genes that originated in eukaryotes that are the hosts for numerous species of bacteria.
D) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic archaeans.
B
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a. apomorphy b. exaptation c. polymorphy d. homology e. homoplasy
In complex land plants, the diploid stage is resistant to adverse environmental conditions, such as dwindling water supplies and cold weather. The diploid stage progresses through which sequence?
a. gametophyte ? male and female gametes b. spores ? sporophyte c. zygote ? sporophyte d. zygote ? gametophyte e. spores ? gametophyte
What microscope uses a metal-and-diamond probe to produce a three-dimensional image?
a) Atomic force microscope b) Darkfield microscope c) Phase-contrast microscope d) Transmission electron microscope
It is a cool winter evening, and you are feeling a little chilled. To warm yourself up you sip some hot tea. As you swallow, you can feel the tea warm your mouth and throat. The drink is warming you up by the process of
A) convection. B) induction. C) conduction. D) radiation.