A Large Proportion of Archaeans Are Extremophiles, So Called Because

question 53

Multiple Choice

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.

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Definitions:

Unique Characteristics

Distinctive attributes or features that set something apart from similar entities.

Rent Controls

are government policies or laws that limit the amount landlords can charge for leasing properties to protect tenants from rapid increases in rent.

Equilibrium Price

The market price at which the quantity of goods supplied is equal to the quantity of goods demanded.

Shortage

A situation in which demand for a good or service exceeds its supply in a market.