Exam 23: Microbial Symbioses

Several rhizobial species within a cross-inoculation group should be able to grow with particular legume species such as alfalfa. However, the same cross-inoculation group would be unable to associate with another legume species such as peas.

How do Hawaiian bobtail squids prevent all bacteria EXCEPT Allivibrio fischeri from colonizing their light organ?

Bacteria associated with plants fix very small amounts of nitrogen, therefore they do NOT contribute significantly to the global N cycle.

Riftia tube worms contain unusual hemoglobins that bind(s)

Ruminants digest bacterial cells as a primary source of

The attine ant is entirely dependent on multiple microbial species for its source of food. What microbial species are involved and what is their role in this multi-partner symbiosis?

What is the primary benefit to phototrophic microorganisms associated with corals?

Most nitrogen-fixing bacteria symbiotically associated with plants are called

Horizontal gene transfer from symbionts to the DNA of their host nematodes is rare.

What is coral bleaching and how might corals be able to adapt to avoid the destruction of coral reefs?

The specificity of certain rhizobia to infect only particular plants is in part due to the

An individual tree can maintain a symbiotic relationship with many different species of mycorrhizae simultaneously.

The rumen is an ________ habitat that depends on ________ to digest cellulose for ruminant animals.

Why do obligate symbionts often contain lower G+C content when compared to free-living organisms?

Which bacterium contains a large Ti plasmid and causes crown gall disease in plants?

Two organisms that both benefit from each other are in a symbiotic relationship called

________ in insects are intracellular bacteria that are usually localized to specialized organs within their host.

A mutant of Rhizobium leguminosarum is able to survive and reproduce in the laboratory outside of plant roots, but can no longer initiate root nodule formation. What type of genes are most likely mutated in this mutant?

Termites lose gut symbionts when they molt. How are they able to maintain a stable gut microbiota?

Which compounds serve as major sources of energy for ruminant animals?