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.
shelducks, genus Tadorna, are a group of large birds in the Tadorninae subfamily of the Anatidae
Anatomy of the large intestine
The Very Large Array (VLA)
The digestive system: functions of the small intestine and large intestine (colon)
Leonardo da Vinci, Study of Human Proportion: The Vitruvian Man.
Rubella rash in a young child. Rubella is also called 3-day measles or German measles.