Question 1

Which process describes the conversion of organic nutrients into inorganic minerals by microbes in an ecosystem?

Accepted Answer

Dissimilation

Question 2

In the marine ecosystem, which group is primarily responsible for CO$$_2$$ fixation and biomass production?

Accepted Answer

Phototrophic bacteria

Question 3

What is the main function of decomposers in a food web?

Accepted Answer

Breaking down dead organisms to recycle nutrients

Question 4

Which symbiotic relationship is exemplified by Rhizobium bacteria and leguminous plants?

Accepted Answer

Mutualism

Question 5

A fungus provides shelter, water, and minerals to its photosynthetic partner, while the partner generates organic carbon and fixes nitrogen. This describes which symbiotic system?

Accepted Answer

Lichen mutualism

Question 6

Which zone of the ocean contains the highest concentration of microbes?

Accepted Answer

Neuston

Question 7

During wastewater treatment, which stage involves microbial decomposition of organic content?

Accepted Answer

Secondary treatment

Question 8

What is the role of leghemoglobin in legume root nodules?

Accepted Answer

Sequestering excess oxygen

Question 9

Which method is most useful for identifying the functional potential of unculturable microbes in a community?

Accepted Answer

Metagenomic shotgun sequencing

Question 10

A researcher wants to measure the rate of carbon fixation in a planktonic community. Which experimental approach should they use?

Accepted Answer

Incorporation of radiolabeled $$^{14}CO$_2$$

Question 11

Which of the following is a consequence of coral bleaching?

Accepted Answer

Loss of reef formation and coastal shelf ecosystems

Question 12

Which of the following best describes the function of haustoria in fungal plant pathogens?

Accepted Answer

Absorbing nutrients from the host without breaking the plasma membrane

Question 13

Which of the following is NOT a typical consumer in a microbial food web?

Accepted Answer

Primary producers

Question 14

Mixotricha paradoxa is notable for which of the following reasons?

Accepted Answer

It is a ciliate with multiple bacterial symbionts that digests cellulose in termites

Question 15

Which of the following statements about the human microbiome is correct?

Accepted Answer

It is metabolically similar between individuals despite taxonomic differences

Question 16

Which equation best represents the process of nitrogen fixation by rhizobia?

Accepted Answer

$$N_2 + 8H^+ + 8e^- + 16$$ATP \rightarrow 2NH_3 + $$H_2 + 16$$ADP + 16P_i$$

Question 17

Which of the following is a major threat to coral reef ecology?

Accepted Answer

Global warming

Question 18

In a municipal wastewater treatment plant, which step is responsible for removing insoluble particles?

Accepted Answer

Primary treatment

Question 19

Which of the following best explains why different body sites have distinct microbial communities?

Accepted Answer

Biotic and abiotic factors such as pH, oxygen, and nutrient availability select for different microbes

Question 20

Which of the following is a direct result of metagenomic analysis of seawater?

Accepted Answer

Identification of approximately 25,000 different microbial species per liter

Microbial Ecology: Structure, Function, and Symbiosis in Ecosystems and Hosts

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