Micro Exam 4

The rhizosphere is __________.

the soil immediately surrounding the root of a plant (ecology)

Compared with pure cultures grown in the lab, microbes in nature usually experience a wider range of environmental conditions, more variation in conditions over time, and more contact with other organisms. Therefore, the same organism in nature will __________.

Typically grow slower than in pure culture

Which of the symbiotic associations listed has bacteria in the most similar role to the bee gut microbiota described in the introductory essay? Consider the specific metabolic interactions, not the general category of relationship.

-Synergistes jonesii in Hawaiian ruminants that prevent the buildup of toxic metabolic products -Fibrobacter succinogenes in ruminants that help to digest cellulose (ecology)

Although it is important to study the organisms that live in the abyssal and hadal zones, researchers can often more easily study organisms that live closer to the ocean's surface, which do not require the use of remotely operated vehicles and similar equipment for sampling. The photic zone is the region in which the light intensity is sufficient for photosynthesis to occur. In the open ocean of tropical and subtropical regions, the photic zone is dominated by several ecotypes of the bacterium Prochlorococcus. Each ecotype dominates a particular depth range of the photic zone. Which of the following reasons are thought to be responsible for this phenomenon?

-The ecotypes differ in ability to photosynthesize and compete effectively at different light intensities -The ecotypes vary in ability to compete for different nitrogen and phosphorus sources (ecology)

Since arbuscular mycorrhizae (AM) have existed before the legume-root nodule associate, why isn't more known about the AM symbiosis?

-The fungal partner cannot be maintained in pure culture in the lab -The fungal partner genetics is largely unknown -The fungal partner can obtain nutrients only from living cells (ecology)

Fluorescent in situ hybridization (FISH) can be used to determine __________.

-how many Salmonella typhimurium cells are present in a sample of unpasteurized apple juice -The phylogenetic diversity of environmental sample -whether a specific piece of mRNA is being produced (ecology)

Place the steps of root nodule formation in the correct order. 1. bacteroid formation 2. nod factor secretion 3. invasion 4. recognition of partners 5. mature nodule

4, 2, 3, 1, 5 (ecology)

Because there is low availability of organic material or reduced inorganic energy sources, the ___________________ in these ecosystems is low

BOD (biochemical oxygen demand) (ecology)

-A common genus is Pelagibacter -Some types found in the photic zone carry out aerobic photosynthesis -Based upon current knowledge, they are predominant prokaryotes above 1000 m

Bacteria (ecology)

All of the following are true of biofilms EXCEPT that __________.

Biofilms are composed of only one species at a time (ecology)

You would like to determine the rate of production of carbon dioxide in a specific microbial habitat. How could you do this without growing the microorganisms in the lab?

By using a microsensor (ecology)

-Association is present in paleo- records -The symbiotic association is obligate -There is a loss of genes for catabolic pathways in the host -Bacterial DNA is found in the host nuclear genome. The symbiotic association is not obligate (required) -There is a loss of genes for anabolic pathways in the host

Evidence for extended coevolution (ecology)

The type of mycorrhizae found associated with forest trees like pines is __________.

Ectomycorrhizae (ecology)

The conditions of nutrient availability, pressure, and temperature result in long __________________ and thus slow __________________

Generation times Growth rates

The phylogenetic diversity analysis of complex microbial communities often targets small subunit (SSU) ribosomal RNA genes. This is because rRNA is found in all organisms and __________.

Is highly conserved over evolutionary time (ecology)

How does the bobtail squid select only Aliiovibrio fischeri for colonization of the light organ?

It produces nitric oxide in the mucus and light organ (ecology)

-Mycorrhizae help plants absorb nutrients while receiving carbohydrates from the plants -Honeybees have gut microbes that help them to digest sugars, while the microbes gain a safe place to live and a supply of food

Mutualism (ecology)

Many plant species grow better with ________ associated with their roots

Mycorrhizae (ecology)

The evolution of plants that grow on dry land is thought to have depended in part on their development of symbiotic associations with which group of microorganisms?

Mycorrhizae (ecology)

Legumes contain __________ in nodules

Nitrogen-fixing bacteria (ecology)

Microbial metabolic activities lower the pH and inhibit growth of other microbes

None of the listed responses is correct (ecology)

-The symbiotic association is not obligate (required) -Analysis of rRNA shows many species are present within the host (as in the microbial rumen) -Phylogenetic analysis suggests that both symbionts share a common ancestor

Not evidence for extended coevolution (ecology)

Deep sea sediments are typically ________, having very low nutrient availability

Oligotrophic (ecology)

A microbe that benefits at the expense of its host without causing a disease

Parasitism (ecology)

-Vivrio cholerae produces an enterotoxin that causes severe diarrhea in humans -Clostridium botulinum produces a neurotoxin, causing botulism in humans if consumed

Pathogenicity (ecology)

Deep sea ocean ecosystems in the region of hydrothermal vents typically have much higher biomass with greater presence of larger eukaryotic organisms than other deep sea ecosystems. Which of the following is most responsible for this difference?

Presence of substantial amounts of highly reduced inorganic compounds and methane

Deep sea organisms live in habitats that are characterized by high _________ and low ______________

Pressures; Temperatures (ecology)

A small farm pond containing many species of microorganisms (bacteria, cyanobacteria, algae, and protozoa) was perturbed when runoff from a manure pile entered the pond. The added nutrients soon turned the water green due to a bloom of cyanobacteria. How did this affect the microbial community in the pond?

Species richness decreased and species abundance increased

What benefit does the fungal partner get from the lichen relationship?

The alga produces organic compounds as nutrients for the fungus (ecology)

In a lichen symbiotic association between a fungus and a cyanobacterium growing on a bare rock surface, the phototroph clearly benefits the fungus by fixing carbon from CO2. The fungus benefits the cyanobacterium in ALL BUT which of the following ways?

The fungus oxidizes organic matter, providing CO2 to the cyanobacterium (ecology)

In a body of freshwater, the transition between the warmer upper layers and the colder lower layers of water is called the __________.

Themocline (ecology)

-Most are inactivated by hydrolytic enzymes or sunlight -They are the most numerous biological entities in seawater -Turnover in seawater is relatively rapid; the populations are replaced within a few days or weeks

Viruses (ecology)

The introductory passage describes research to understand the honeybee and bumblebee gut microbiota. It mentions that honeybees are affected by the loss of their gut microbiota. Which of the following experimental results best supports the hypothesis that this interaction is a mutualism?

When you culture the honeybee gut microbiota outside of the gut and raise honeybees without the gut microbiota, the microbes do not grow as well, and the bees are more likely to develop infections (ecology)

Part complete Trace elements are found in bacterial cells in very small amounts because they __________.

function only in a limited set of enzymes and cofactors (microbial metabolism pt 1)

Bacterial degradation of cellulose and fermentation of glucose occur in the rumen of cows, sheep and other ruminant animals. The main source of energy for the fermenters is __________, while the main source of energy for the ruminant is __________.

glucose; volatile fatty acids (ecology)

The ________________ contains 13-69 epibionts and a flagellated bacillus..

green sulfur bacterial consortium (ecology)

Some lichen symbionts can survive independently on bare rocks in the absence of any external source of organic matter due to the ability of the phototrophic partner to fix CO2 from the air, and __________.

nitrogen fixation by the cyanobacterial partner (ecology)

Termites are capable of digesting cellulose and hemicellulose due to the presence of __________.

symbiotic bacteria in their gut (ecology)

To help digest sugar, honeybees have _______________

symbiotic gut bacteria (ecology)

-Most of these living below 1000 m are thought to be ammonia oxidizers -Below 1000 m the most common phylum is Thaumarchaeota -They increase to near 50% of total prokaryotes below 1000 m

Archaea (ecology)

E. coli bacteria use up oxygen in the human colon, allowing obligate anaerobes to survive

Commensalism (ecology)

-attempting to grow the honeybee microbiota in the lab outside of the gut -producing mycorrhizal spores in the lab to develop inoculants to improve plant growth

Culture dependent (ecology)

-Using 16S rRNA gene sequencing to determine species in green bacterial consortia -Sequencing termite gut microbiota to study their diversity -Using metagenomic analyses to determine whether specific bacteria have the genes for nitrogenase

Culture independent (ecology)

An organic farmer is having problems with a particular insect pest in his fields and has consulted the local agricultural extension office for possible solutions. He cannot use pesticides on his fields if he is to maintain his organic certification. You are consulted about the possible use of an entomopathogenic nematode as a means of controlling the insect pest. You need to consider ALL BUT which of the following?

You must be wary of the nematode killing beneficial insects like pollinating bees, because they are generalist pathogens (ecology)

Benefits of a nodulated plant include __________.

increased plant yield due to nitrogen fixation (ecology)

Part complete A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider__________.

inoculating his fields with the appropriate cross-inoculation group of rhizobia (ecology)