Exam 26: Bacteria and Archaea

Why are genes associated with nitrogen fixation NOT typically used to identify bacteria species?

Humans provide ecological niches for bacterial populations.

What can scientists study to gain a better understanding of prokaryotic life on Earth millions-if not billions-of years ago?

Fermentation yields an amount of energy equivalent to respiration because both processes achieve full oxidation of carbon compounds to CO₂.

Given its prevalence in the intestines of African children, Prevotella bacteria would MOST likely belong to which of the following groups (Fig. 26.24)?

Molecular features that distinguish major groups of Bacteria evolved billions of years ago. The DNA sequences continued to change within each group, potentially masking inherited sequence similarities from a common ancestor that otherwise would have defined the group.

Archaea and Bacteria are involved in which of the following cycles?

Given the features found individually in Archaea, Bacteria, and Eukarya, what features were probably present in the last common ancestor of all living things?

A researcher is culturing several different strains of bacteria in the same petri dish. One day, he finds that all of the strains have died off except one. He continues to grow his bacteria for several weeks, and new strains develop. However, after a month he again notices that all but one of his bacterial strains have died off. This is an example of _____ selection.

An organism that oxidizes H₂S to gain energy and utilizes CO₂ as a carbon source (to generate carbohydrates) would be classified as a:

Streptomycetes are gram-positive bacteria that are capable of producing antibiotic-like compounds, which are the basis for widely used antibiotics such as erythromycin.

Which of the following characteristics are unique to eukaryotes (i.e., do NOT occur in either archaea or bacteria)?

Which of the following statements is TRUE regarding microbial mats?

Based on what you know of the preferred growth conditions for certain Archaea species, why would a cow stomach be an ideal environment to house archaeons?

A major constituent of Earth's atmosphere is nitrogen gas (N₂), which makes up 79% of the air we breathe. Primary producers such as plants and algae cannot assimilate this form of nitrogen into biomolecules. Instead they rely on Bacteria and Archaea to convert N₂ to ammonia (NH₃). This important biological reaction is called:

If scientists could quantify all the bacterial and human cells on Earth, they would find that there are far more human cells.

A researcher wants to determine if a unicellular organism he discovered is an autotroph or a heterotroph. He radioactively labels the carbon in CO₂ and C₆H₁₂O₆, and exposes one culture of his organism to the labeled CO₂ and another culture to the labeled C₆H₁₂O₆. What would happen if his organism is an autotroph?

Which of the following organisms can function as chemoautotrophs?

The microbial nitrogen and sulfur cycles have many features in common. In what ways are they different?

We typically think of bacteria as inhabiting human intestines. In (or on) what other locations of a healthy human body would you expect to find bacteria?