Exam 22: Microbial Symbioses

The signaling factors of arbuscular mycorrhizae most likely gave rise to the signaling factors used in rhizobial nodule formation,yet less is known about arbuscular mycorrhizae because

Where are ectomycorrhizae MOST commonly found?

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

Both pathogenic bacteria and primary symbionts have a tendency to lose genes for catabolic pathways.

The reproductive systems of many insects can be manipulated by parasitic symbionts,which are passed down to each generation and can skew the sex ratio of their progeny.

Due to the close interactions with other organisms,obligate symbionts generally have larger genome sizes compared to other non-symbiotic bacteria.

How are root nodule and arbuscular mycorrhizal symbioses similar?

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

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

Archaea are commonly present in rumens.

Consortia of a phototrophic green sulfur bacteria and motile heterotrophs are found worldwide in freshwater stratified sulfidic lakes.

Biofilms in the human mouth primarily contain pathogens.

Plant diversity is generally lower in environments where mycorrhizae are associated with plants due to strong coevolution,which leads to competitive exclusion.

Bacterial symbionts of termite hindguts play a critical role in the termite's

Aphids that feed on carbohydrate-rich but nutrient-poor foods obtain________ from their endosymbiotic bacterial partners.

In insects,primary symbionts are ________,while secondary symbionts ________.

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

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

A species of insect that lives solely on pine sap was found to contain a bacterial symbiont.Genome sequencing of both the host and the symbiont revealed that the symbiont lacked many genes required for energy production,and the host lacked genes for biosynthesis of several essential amino acids.What is/are the most likely mechanism(s)that caused the loss of these genes?

Fungi and protists serve an important role in the anaerobic digestion of cellulose in ruminants.