Exam 22: Microbial Symbioses

How are symbiotic relationships important in agriculture and food production? Use at least two different examples to support your answer and explain how understanding these symbioses could help produce more food.

Riftia tube worms contain unusual hemoglobins that bind(s)

In mycorrhizal mutualisms between plants roots and fungi,

The gut flora is relatively stable over long time periods in healthy adults,suggesting its highly evolved role in the human body.

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.

Which of the following is NOT true of human gut microbes?

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?

Genome sequencing of the bacterial symbionts of animals has allowed us to compare the genomic features of several symbionts.The following data were collected on two insect symbionts: Symbiont A: 0.4 Mb genome,20% G+C content,missing or incomplete peptidoglycan synthesis and nucleotide synthesis pathways. Symbiont B: 1.8 Mb genome,40% G+C content,peptidoglycan and most nucleotide synthesis pathways complete. What can you deduce about these two insect symbionts based on their genomes?

The insect symbiont Wolbachia can be used to suppress disease transmission by mosquitoes because

Two-thirds of terrestrial environments support growth of termites.

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

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

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

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

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

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

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

Which of the following is a common feature of primary insect symbionts?

Allivibrio fischeri symbionts benefit the Hawaiian bobtail squid by

Where are ectomycorrhizae MOST commonly found?