A Large Proportion of Archaeans Are Extremophiles, So Called Because

question 15

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 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.

---

Definitions:

Strong

This term could refer to various contexts but lacks a specific definition without additional context; thus, it's not clearly identifiable as a unique key term.

Assessment

The systematic evaluation and measurement of psychological, biological, and social factors in an individual or group.

Testing

The process of administering assessments to evaluate skills, knowledge, abilities, or performance in various areas.

Records And Documentation

Written materials and other evidence, including electronic and paper formats, that provide a record of activities, transactions, and decisions.