During the Jurassic Period, several different mammalian lineages independently evolved an herbivorous lifestyle for obtaining energy. This has resulted in
A) different digestive patterns in herbivorous animals, some that depend on gut microbiota to digest plant material and some that do not.
B) different digestive patterns in herbivorous animals that all depend on gut microbiota to digest plant material.
C) the evolution of foregut fermentation, as seen in ruminants, as the only digestive pattern that depends on fermentative gut microbiota.
D) horizontal gene transfer of genes for glycoside hydrolases and polysaccharide lyases from bacteria to mammals.
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
A) they cannot be maintained in pure culture.
B) they are not as important for plant health.
C) no genetic systems have been developed for fungi.
D) they are not as important for plant health and no genetic systems have been developed for fungi.
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?
A) rhz genes
B) myc genes
C) nif genes
D) nod genes
How are root nodule and arbuscular mycorrhizal symbioses similar?
A) They both use lipochitin oligosaccharide signaling factors to initiate root colonization.
B) They both supply nitrogen to the host plant through nitrogen fixation.
C) They both increase absorption of nutrients from soil.
D) They are both required for the growth and reproduction of their host plants.
Which of the following is a common benefit of a microbe-plant symbiosis?
A) increased nutrient availability
B) decreased pathogen colonization
C) increased affinity for carbon dioxide
D) increased nutrient availability and decreased pathogen colonization
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